Crop Protection

Published by Elsevier
Online ISSN: 0261-2194
Publications
Article
Small-scale farmers in Northern Tanzania grow vegetables that include tomatoes, cabbages and onions and use many types of pesticides to control pests and diseases that attack these crops. Based on the use of questionnaires and interviews that were conducted in Arumeru, Monduli, Karatu, and Moshi rural districts, this study investigates farmers' practices on vegetable pest management using pesticides and related cost and health effects. The types of pesticides used by the farmers in the study areas were insecticides (59%), fungicides (29%) and herbicides (10%) with the remaining 2% being rodenticides. About a third of the farmers applied pesticides in mixtures. Up to 90% had a maximum of 3 pesticides in a mixture. In all cases there were no specific instructions either from the labels or extension workers regarding these tank mixtures. Fifty three percent of the farmers reported that the trend of pesticide use was increasing, while 33% was constant and 14% was decreasing. More than 50 percent of the respondents applied pesticides up to 5 times or more per cropping season depending on the crop. Insecticides and fungicides were routinely applied by 77% and 7%, respectively by these farmers. Sixty eight percent of farmers reported having felt sick after routine application of pesticides. Pesticide-related health symptoms that were associated with pesticides use included skin problems and neurological system disturbances (dizziness, headache). Sixty one percent of farmers reported spending no money on health due to pesticides. These results can be used to develop a tool to quantify the cost of pesticide use in pest management by small-scale vegetable farmers in Northern Tanzania and contribute to the reformation of pesticide policy for safe and effective use of pesticides.
 
Article
‘Double-low’ (00) varieties of oilseed rape (Brassica napus L. var. napus) have lower seed concentrations of certain astringent chemicals than have ‘single-low’ (0) varieties and as a result it has been suggested that plants of the 00 varieties may suffer higher damage by mammal and bird pests. Regular damage surveys were conducted over the winter months on 23 farms where 0 and 00 varieties of oilseed rape were being grown in close proximity. Samples of foliage were taken each month and analysed for levels of S-methylcysteine sulphoxide (SMCO) and various glucosinolates. There was no evidence that either rabbits (Oryctolagus cuniculus) or woodpigeons (Columba palumbus) preferred to feed on the 00 rather than the 0 varieties. The two types did not significantly differ in the foliage concentrations of SMCO or any glucosinolate. The concentrations of all the chemical constituents analysed fell significantly between February and April. There were no significant correlations between the level of damage in a field and the concentrations of SMCO or glucosinolates in the foliage of the plants grown there. There were significant correlations between the SMCO and glucosinolate concentrations in the 0 and 00 varieties grown on the same farm. This suggests that factors associated with climate, geographical location, soil type and/or cultivation may have a greater effect on the foliage concentrations of these chemicals than has the variety of the plant.
 
Article
The potential of benzo-(1,2,3)-thiadiazole-7-carbothioic acid S-methyl ester (BTH) to trigger systemic acquired resistance (SAR) in tomato (Lycopersicon esculentum. Mill cv. Vollendung) plants against a yellow strain of Cucumber mosaic virus (CMV-Y) was investigated. Application of BTH, as a drench, 7 days before inoculation with CMV-Y, protected plants against the necrosis caused by CMV-Y. The resistance was evident as a decreased disease incidence and severity in BTH-treated plants. Twenty-one days after challenge inoculation with CMV-Y, the disease incidence in plants with SAR did not exceed 12.5% whereas, 91.7% of control plants were severely infected. The development of primary disease symptoms in BTH-treated plants was delayed for 7 days. The disease spread rapidly in control plants and by the end of the experiment almost all control plants showed severe mosaic and leaf necrosis. Results of enzyme-linked immunosorbent assay (ELISA) indicated that BTH treatment affected virus replication in protected leaf tissues. Analysis of the newly developed leaves of BTH-treated plants for virus antigen revealed that symptomless plants failed to support the replication of CMV-Y and the concentration of the virus in these plants was similar to that in uninoculated control plants.
 
Article
Small-plot research and large-field validations were conducted to determine the effect of 1,3-dichloropropene (1,3-D)+chloropicrin (Pic) application methods in combination with the herbicides pebulate and napropamide on pest control in fresh market tomato (Lycopersicon esculentum Mill.). In both the small-plot trials and the large-validation fields, various treatments compared the efficacy of soil fumigants and herbicides based on methyl bromide, in-bed and broadcast applications of 1,3-D+Pic, pebulate, and napropamide. The results consistently indicated that either in-bed or broadcast applications of 1,3-D+Pic in combination with pebulate and napropamide are equally effective against the weed Cyperus spp., the nematodes Tylenchorhynchus spp., Belonolaimus longicaudatus, and Meloidogyne spp., and the soilborne disease Fusarium oxysporum f.sp. lycopersici in fresh market tomato. Therefore, broadcast 1,3-D+Pic application can reduce personnel exposure and poisoning risks, without losing pest control efficacy.
 
Article
InLine (Dow AgroSciences LLC, Indianapolis, IN, USA), a commercial formulation of 1,3-dichloropropene (1,3-D; 61%) plus chloropicrin (33%), is one of the potential replacements to methyl bromide for soil fumigation. The efficacy of 12 InLine concentrations (80–19,520 μmol kg−1) to control five species of weed seeds and four soilborne pathogens was evaluated in a laboratory dose–response study after 24 h of exposure to fumigants in a sandy loam soil at 20 °C in microcosms. Logistic dose–response models were used to estimate the effective concentration to reduce weed seed and pathogen viability by 50% (LC50) or 90% (LC90). Among the weeds, the seed of Portulaca oleracea was the most sensitive to soil fumigation with InLine (LC50=352 μmol kg−1, LC90=583 μmol kg−1), followed by Stellaria media and Polygonum arenastrum with LC90 values of 780 and 1636 μmol kg−1 soil, respectively. The seeds of Malva parviflora and Erodium cicutarium were not sensitive to fumigation up to the highest InLine dose of 19,520 μmol kg−1 soil. Among the pathogens, Pythium ultimum (LC50=30 μmol kg−1 soil, LC90=46 μmol kg−1 soil) was the most sensitive and Verticillium dahliae (LC50=625 μmol kg−1 soil, LC90=2735 μmol kg−1 soil) was the least sensitive to InLine fumigation. Phytophthora cactorum and Fusarium oxysporum exhibited intermediate susceptibility to this soil treatment (LC50⩽397 μmol kg−1 soil, LC90⩽1113 μmol kg−1 soil). In this sandy loam soil, InLine at a concentration of 1636 μmol kg−1 reduced the viability of Portulaca oleracea, S. media, Polygonum arenastrum seeds and all fungi pathogens tested (except for V. dahliae) by 90% at 20 °C after 24 h exposure.
 
Article
Two application methods, single- and double-chisel injection of the fumigant nematicide 1,3-dichloropropene (1,3-D) were evaluated for efficacy and environmental fate in pineapple field experiments. The objectives were to compare the 1,3-D soil distribution between injection methods, evaluate volatile losses to the atmosphere, and to determine efficacy with each method. In a small-plot field experiment, 1,3-D (224, 337, and 393 1 ha−1) was manually injected 30 cm deep with fumiguns to simulate the commercial practice of a single- or double-chisel injection per planting bed. 1,3-D concentrations in the soil atmosphere and in soil samples were determined and compared to nematode control. In two large-scale field experiments, 1,3-D (224 1 ha−1) was applied with commercial injection equipment with and without polyethylene mulch. Air monitoring for 1,3-D showed a reduction in 1,3-D air emissions with single-chisel injection compared with double-chisel injection. In all experiments, the two injection methods resulted in equivalent 1,3-D concentrations in the plant line. Single-chisel injection resulted in improved retention of 1,3-D within the planting bed as shown by low 1,3-D soil concentrations in the interbed. Nematode counts and bioassay studies found equivalent nematode control in the planting bed with either injection method. The single-chisel method, however, resulted in reduced nematode control in the interbed region.
 
Article
A mixture of 1,3-dicloropropene 60.5% w/w and chloropicrin 33.3% w/w (Telone C35 EC) may be registered in Italy for soil drip fumigation. Five experiments on greenhouse tomatoes in Northern, Central and Southern Italy compared the effectiveness of this mixture in comparison with methyl bromide to find the optimum application rate in soils infested by Fusarium oxysporum f.sp. lycopersici, F. oxysporum f.sp. radicis lycopersici, Sclerotium rolfsii, Meloidogyne javanica and M. incognita. Its efficacy against F. oxysporum f.sp. radicis lycopersici and M. incognita was confirmed when applied to soils at 100, 200, 300 and 400 l ha−1 (132.4, 268.4, 402.6 and 536.8 kg ha−1) under gas-tight films with 15–45 mm of application water (900–1200 mg Telone C35 EC l−1). In sandy soils, with slight F. radicis lycopersici infections and with heavy nematode (M. incognita) attacks, the mixture, drip applied at 900 mg l−1 during late summer (fumigation: late summer; transplant: late-summer/autumn; last harvest: early spring), performed well up to 132.4 kg ha−1 (100 l ha−1). In sandy loam soils with slight F. radicis lycopersici infections and severe infections of F. lycopersici and galling nematodes (M. javanica), 268.4 kg ha−1 (200 l ha−1) of the mixture applied at 900 mg l−1 as a drip provided yields similar to those of methyl bromide treated plots both in spring and summer cycles. In sandy loam soils, the diseases (F. lycopersici, F. radicis lycopersici) were controlled at rates ⩾268.4 kg ha−1 (containing 90 kg ha−1 of chloropicrin), but the mixture was ineffective against Sclerotium rolfsii occasionally observed in sandy loam soils. In both sandy and sandy loam soils, no significant relationships were found between the rates of mixture applied (132.4, 268.4, 402.6 and 536.8 kg ha−1) and the degree of nematode infestation.
 
Article
One hundred and fifty F6 inbred durum wheat lines derived from Kunduru-1149×Cham-1 cross were characterised in terms of their response to yellow rust (Puccinia striiformis) race population including Yr2, Yr6, Yr7 and Yr9 virulence genes. The results revealed that there is a considerable amount of genetic variation among these lines and yellow rust resistance in durum wheat is highly heritable (92%). Twenty-five of 150 lines (16.67%) were found totally immune, 104 of them (69.33%) were found to be resistant or moderately resistant while only 21 of them (14%) were found to be susceptible. Hence, 86% of the lines tested in this study could be used as a source of yellow rust resistance in breeding programmes.
 
Article
We tested persistence and effects of dilution of a hydrolyzed protein edible insecticide bait for control of tropical fruit flies (Tephritidae). The bait, commercially marketed as GF-120, is a mixture of the insecticide spinosad, a microbially hydrolyzed protein, sugars, adjuvants and a series of conditioners. Bait is formulated to have both an attractant and feeding stimulant function. In experiments to determine the maximum persistence of the commercial formulation we found that if bait is protected from rain but exposed to other environmental factors (heat, sunlight, humidity) the bait remained effective for about 14 days in field cages. In a laboratory cage test experiment to determine the effects of spinosad concentration in the commercial bait after exposure to field conditions, concentrations of 8 mg AI l−1 bait did not differ from the control (no spinosad). Concentrations of 80 mg l−1 had significantly lower knockdown (kill flies within 2 h) than 800 mg l−1, but the two concentrations did not significantly differ in numbers of survivors over a 4 day treatment period time. Field cage tests showed significant differences among spinosad concentrations and bait ages for knockdown of flies but 80 and 800 mg spinosad l−1 were similar for rates of survival over 4 day tests. A final test was performed to measure the effects of bait+insecticide dilution on function of the bait after 14 days aging in the field cage. Results showed that a four-fold dilution of the complete bait did not significantly reduce attraction or knockdown. The undiluted bait was superior to eight-fold dilution but did not differ from four-fold dilution.
 
Article
From 20 August to 19 September 1993 and 1994, we assessed the effects of treating ripening sunflower fields with DRC-1339-treated rice baits on blackbird (Icterinae) damage to sunflower fields found within ⩽ 3.2 km of blackbird roosts. The number of blackbirds () using roosts centered within the treated and untreated test areas were similar (P = 0.432). The number of blackbirds using sunflower fields in the test areas did not vary among days after treatment (P = 0.538) or between treated and untreated areas (P = 0.203, averaging 3203 ± 361). The percentage of sunflower damage did not differ (P = 0.736) between treatments (). It appears broadcasting DRC-1339-treated rice baits in ripening sunflower fields does not reduce local blackbird populations or sunflower damage.
 
Article
[14C]Cymoxanil was applied to either the root system or to the foliage of tomato plants and its uptake, translocation and degradation was followed using autoradiography, combustion and thin-layer chromatographic analyses of water or methanolic extracts. Cymoxanil was taken up by the root system within 1 h and translocated to cotyledons, stem and leaves within 16 h. The compound was degraded, mostly to glycine, within 16–44 h, in the root and all parts of the shoot. When applied to the surface of leaf 2 of five-leaf plants, enhanced uptake, translocation and degradation (mainly to glycine) of [14C]cymoxanil was observed in plants treated with a mixture of oxadixyl and [14C]cymoxanil, compared with plants treated with [14C]cymoxanil alone. Root application data confirm that cymoxanil is a systemic compound with a short persistance in tomato plants. Foliage application data suggest that the well-documented synergistic interaction between cymoxanil, oxadixyl and mancozeb in controlling plant diseases caused by Peronosporales does not result from a delayed degradation of cymoxanil in the presence of the other fungicides; the mechanism of synergism has not yet been elucidated.
 
Article
Systematic rat control was developed in oil palm plantations in the 1960s and 1970s by comparing bait mixtures and application techniques mainly for anticoagulant poisons, in trials with related ecological studies. Rattus tiomanicus populations of 100–600/ha were estimated in plantings of a range of ages and localities, and numbers fluctuated slowly within these limits in a single plot without control, monitored over 20 years. Optimum control was with maize based wax-bound baits (ca. 12 g), applied one per palm (generally 114–138/ha) with “replacement rounds” of those taken, at 4-day intervals until acceptance declined below 20% (usually about 5 or 6 rounds), doing large areas at 6-month intervals to minimise intermediate build up. Potential losses are estimated at 5–10% of the palm oil product, worth, within the wide price limits of recent years, from $(US)48 to 288/ha. Baiting cost is around $15/ha. Events since 1982 include appearance of warfarin resistant populations (but “second generation” anticoagulants remain effective); the replacement of the formerly ubiquitous and virtually sole rat of mature oil palms, R. tiomanicus, by R. rattus diardii, in several localities; and some populations displaying non-acceptance of baits.
 
Article
Fungicides are routinely used to prevent yield losses in winter wheat in southern Sweden. Yield and 1000 grain weight (TGW) data from 432 trials in farmers' fields were evaluated to review long-term yields (1977–2005) and control of eyespot and Leaf Blotch Diseases (LBDs, including Septoria tritici blotch, Stagonospora nodorum blotch and tan spot), powdery mildew, brown rust and yellow rust. Regression analyses revealed that control of LBDs explained 74% of the yield increase achieved by fungicide treatment at GS 45–61, followed by powdery mildew (20%), brown rust (5%) and yellow rust (1%). Yield of both untreated and fungicide-treated plots increased from approx. 6000 to 12 000 kg ha−1 over the period 1983–2005. Single eyespot treatment improved yield by ∼320 kg ha−1 yr−1 during the period 1977–2002, mainly due to occasional years with severe eyespot. Single leaf disease treatment at GS 45–61 increased mean yield by 10.3% or 810 kg ha−1 yr−1 (9.9% or 660 kg ha−1 yr−1 for 1983–1994 and 10.7% or 970 kg ha−1 yr−1 for 1995–2005) due to increased TGW and grain numbers, especially in high-yielding stands. Additional extra early treatment at GS 30–40 against LBDs increased yield by ∼250 kg ha−1 yr−1. Estimated variance in yield and TGW was higher between years than within years, while that in yield increase and plant diseases was lower between years than within. The results confirm potential and limits of fungicides and the need for supervised control strategies including factors affecting disease, yield and interactions.
 
Article
Suspected cases of poisoning of honeybees by agricultural pesticides are investigated by the Ministry of Agriculture, Fisheries and Food (in England and Wales) and the Scottish Office Agriculture and Fisheries Department (in Scotland). Studies include field visits to sites where bee mortality is recorded, examination of dead bees for disease, and analysis for the presence of pesticide residues. This paper reviews the results of these investigations for the period 1981–1991. Pesticide poisoning is diagnosed from the detection of residues in dead bees, through interpretation in relation to the median lethal dose (LD50), and ‘subsequent residue level’ (SRL) determined from laboratory studies in which bees were exposed to one LD50 dose. Overall, an annual average of 50 incidents were confirmed as due to pesticide poisoning, involving 30 pesticide active ingredients during the 1981–1991 period. In England and Wales, the principal hazards were caused by misuse of the insecticide triazophos on oilseed rape, a problem that has been reduced to low levels during the 1980s, and by dimethoate use on a variety of arable crops. In Scotland there were fewer incidents, most of which were associated with use of fenitrothion on raspberries, and gamma-HCH on oilseed rape. Opportunities for reducing the risks of poisoning, and for refining the investigation of suspected incidents, are discussed.
 
Article
Weather factors are driving forces in plant disease development and differ between years and locations. Results from long-term fungicide field trials 1983–2007 and disease surveys 1988–2007 in winter wheat in southern Sweden were used to evaluate relationships between yield, the yield increase obtained by fungicide treatment, thousand grain weight (TGW), disease severity and disease incidence, and the independent variables air temperature and precipitation as monthly means. These two weather variables explained more than 50% of the variation between years regarding yield increase, TGW, LBDs (Leaf Blotch Diseases, including Septoria tritici blotch, Stagonospora nodorum blotch and tan spot), brown rust, yellow rust and eyespot, but less than 50% of the variation in yield and powdery mildew. Precipitation in May was the factor most consistently related to LBD disease intensity, and adding another two weather factors further improved the degree of explanation. Weather factors in the preceding growing season influenced growth stage, powdery mildew and brown rust. Mild winters and springs favoured the biotrophs such as powdery mildew, brown rust and yellow rust. Statistically significant correlations between incidence and severity were found for LBDs, brown rust and eyespot, but not for yellow rust and powdery mildew. Regression models with disease incidence as dependent variable generally had a higher degree of explanation and lower P-value than models with disease severity as dependent variable. Our results confirm that weather data can be successfully used in wheat disease prediction models.
 
Article
A survey of aphicide use in winter wheat was carried out in the summer of 1984. The survey of more than 60 000 ha revealed that many crops were treated late, dimethoate was the insecticide most frequently used, tank mixes with fungicides were common, and there were regional differences in spray timing and pesticide usage. An existing model of the economic benefits of spraying against the grain aphid (Sitobion avenae F.) was used in conjunction with aphid population assessments in two counties and aphid population predictions from a model, based on aerial samples of aphids, in a third county. The combination of a wide range in aphid population levels between fields, and economically irrational spraying, often resulted in low profits or financial losses. It is proposed that field-by-field decision-making, initiated by a regional forecast and guided by an accessible advisory system based on variable economic thresholds, would improve the accuracy of the decision-making process of cereal farmers in the UK.
 
Article
Aerial spray field trials were conducted in 1992 and 1993 to evaluate the feasibility of reducing the dosage of nuclear polyhedrosis virus applied against gypsy moth, Lymantria dispar (L.), larvae from a double application of 5 × 1011 polyhedral inclusion bodies (PIB) ha−1 (total 1012 PIB ha−1) to double applications of 5 × 1010PIB ha−1 (total 1011 PIB ha−1) or single applications of 5 × 1010 or 1011 PIB ha−1. The reduced dosages were applied with a virus enhancer, Blankophor BBH, in conjunction with a wettable powder formulation developed by American Cyanamid Co. Replicated virus treatments were compared to double applications of Bacillus thuringiensis (B.t.) at 50 BIU ha−1 (Foray 76B) in 1992 and 30 BIU ha−1 (Foray 48B) in 1993. In 1992, three double applications of nuclear polyhedrosis virus at 5.0 l ha−1 application−1, 5 × 1011 PIB ha−1 in water with 25% molasses, 6.0% Orzan LS and 2.0% Bond sticker, 5 × 1011 PIB ha−1 American Cyanamid Co. wettable powder and 5 × 1010 PIB ha−1 American Cyanamid Co. wettable powder plus 1.0% Blankophor BBH, were applied to 13 plots with a combined area of 91.1 ha. One B.t. treatment, a double application of Foray 76B at 50 BIU ha−1 in 2.5 1 ha−1, was applied to three plots with a combined area of 37.0 ha, and four plots with a combined area of 62.0 ha were used as untreated check plots. The reduction in egg mass densities in all treatments was considerable and all post-spray counts were less than the treatment target threshold of 1250 ha−1. Egg mass densities for pre-spray and post-spray counts were similar in the untreated check plots. Corrected population reductions (Abbott's formula) for the three virus treatments were 66, 74 and 84%, respectively, and 95% for the Foray 76B treatment. However, defoliation of red oak, Quercus rubra L., and white oak, Q. alba L., was light and there were no significant differences in defoliation of oak trees between the treated and untreated check plots. In 1993, there were three nuclear polyhedrosis virus treatments using the American Cyanamid Co. wettable powder formulation plus 1.0% Blankophor BBH at 5.0 1 ha−1; a double application at 5 × 1010 PIB ha−1 (total 1012 PIB ha−1), a single application at 5 × 1010 PIB ha−1, and a single application at 1011 PIB ha−1, were applied to 15 10-ha plots, and a double application of Foray 48B at 30 BIU in 2.4 l ha−1 was applied to five 10-ha plots. Five untreated 10-ha plots served as checks. Overwinter mortality of eggs caused a major population decline in the area, and egg mass counts in check plots declined by 77%. Nevertheless, all treatments had a significant impact on the gypsy moth population and corrected population reductions were 68, 63 and 61% for the three virus treatments, respectively, and 63% for the Foray 48B treatment. Mean defoliation was 50% in the check plots, but significantly less in all the treatments. In addition to egg mass counts and defoliation estimates, pupae in burlap traps and male moths in pheromone traps were sampled in both the 1992 and 1993 studies and these results are discussed.
 
Scoring scheme for the Environmental Impact Quotient variables
Mean yield for wheat, spring and winter barley and oilseed rape for the period 1992-2002. Source: DEFRA National Statistics (2005a, b).
Pesticide use, Environmental Impact Quotient and environmental impact values for pesticides used on arable crops
Article
Attempts to direct policy according to scientific findings are hampered by the multidimensionality of the potential impacts of pesticides which may affect consumers, operators, wildlife and the environment. Pesticide risk indices seek to reduce these multidimensional impacts to a single dimension and are increasingly used to understand variation in the hazard inherent in pesticides at the farm, regional and national scale. In this study, we used one such risk index, the Environmental Impact Quotient (EIQ), to estimate the hazard posed by pesticide usage from 1992 to 2002 on four UK grown arable crops (wheat, winter barley, spring barley and oilseed rape).Results are reported for three key indicators of hazard. Firstly, the EIQ which rates a pesticide's hazard profile. Secondly, the Environmental Impact (EI) which is the product of the EIQ rating and data on actual usage of a pesticide at a GB level in a given year, and provides an indication of the overall hazard arising from actual historical use at a national scale. Thirdly, EI per hectare standardises the hazard by dividing total EI in year by the area of crop grown in that year.The results suggest that between 1992 and 2002, the overall hazard posed by the pesticides applied to these crops declined substantially, as evidenced by a 10% decrease in pesticide usage, an 8% increase in yield per hectare, a 14% decrease in overall EIQ rating, a 15% decrease in EI rating and a 7% decrease in EI per hectare. Both Government and the industry may wish to take some encouragement from these trends, which seem to be wholly in line with societal demands of agriculture.
 
Article
MCPA, 2,4-D and their salts, amines or esters have been the most widely used herbicides for many years, especially in cereal crops. They kill broad-leaved plants but not grasses. These phenoxyherbicides have been detected in soil in concentrations reaching 0.63 mg/kg of dry matter. The present work was undertaken in order to study the toxicological effects of commercial preparations: Aminopielik 720 (2,4-D–NH4+ salt, 68% of active ingredient) and Chwastox Extra 300SL (MCPA—Na salt, 30% of active ingredient) on vascular plants. The species tested were the broad-leaved plants Lepidium sativum, Sinapis alba and grasses (cereal plants) Avena sativa, Triticum aestivum. The influence of the commercial products on seed germination and root or shoot growth inhibition of the plants was studied. The tests lasted 168 h. Comparison of the IC50 values for the seed germination and shoot growth inhibition of grasses and broad-leaved plants showed great differences. IC50 values obtained for L. sativum and S. alba were in some cases nearly 100 times lower than the IC50 values for A. sativa and T. aestivum (both in seed germination and shoot inhibition tests). In the case of root growth inhibition, the differences between IC50 values for broad-leaved plants and grasses were less significant for Chwastox Extra. The IC50 values for germination were very high (ranged from 104 to 6704 mga.i. l−1), but for shoot (S) or root (R) growth inhibition they were lower and ranged from 0.15 to 73 mga.i. l−1 (S) and from 0.07 to 12 mga.i. l−1 (R) for broad-leaved plants and grasses, respectively. Thus phenoxyacetic herbicides have been found to inhibit root and shoot growth for both broad-leaved plants and grasses.
 
Article
Four European countries on a north to south trajectory were sampled for their crop protection policies. Selected respondents were interviewed about their expectations with respect to the eventual reduction of pesticide use in the near future. Crop protection, policies among these countries are out of phase: Sweden has successfully completed a plan to reduce pesticide usage to 50% of a base-line value; the Netherlands are in the process of implementing such a plan; France is aiming to achieve supervised control; Spain is trying to reduce pesticide residues in export commodities. Before the year 2000, considerable reductions in the volume of pesticides used can be expected only in the Netherlands. Among the reasons for scepticism with regard to the reduction of dependence on pesticides and pesticide use are ‘lack of alternatives’, ‘inadequate research capacity’, ‘inadequate supervision for observance of regulations’, ‘absence of clear national policies’ and ‘absence of EC policy’.
 
Article
CGA 219417 (proposed common name: cyprodinil) is a pyrimidinamine currently being developed as a foliar fungicide for cereals, grapes, vegetable crops and deciduous fruit. It has a new mode of action and shows no cross-resistance to any current market product. On cereals, CGA 219417 exhibits a broad fungicidal spectrum with good activity against Pseudocercosporella herpotrichoides, Erysiphe graminis, Pyrenophora teres, Rhynchosporium secalis and Septoria nodorum on ears. The strength of CGA 219417 on grapes, vegetable crops and strawberries is its excellent activity against Botrytis spp. On deciduous fruit the key target pathogen genera are Venturia, Alternaria and Monilinia spp. The fungicide has excellent safety for users, consumers and environment. In addition, its other characteristics, such as not being harmful to beneficial organisms, make it a promising product for flexible integrated disease-control practices.
 
Article
The last quarter of the 20th century has seen the withdrawal of many compounds formerly used as fumigants. Methyl bromide, the fumigant with the widest range of applications is scheduled for worldwide withdrawal from routine use as a fumigant in 2015 under the directive of the Montreal Protocol on ozone-depleting substances. Phosphine, the only other commodity fumigant available worldwide, used principally on bulk grain but also on dried fruit, nuts, cocoa, coffee and bagged rice, is currently under regulatory review in the USA and Europe. The prospects for the continued use of fumigants to protect plant and animal health and commodity trading are discussed in the context of mounting pressures on compounds due to registration requirements, atmospheric emission controls, fears on safety or health grounds, the incidence of resistance, and the need to achieve increasingly high standards of pest control in international trade. Some recent research results relating to fumigant toxicity and gas application technology are presented which indicate ways in which the use of some of the few remaining fumigants can be extended in the 21st century.
 
Article
Efficacy of the non-steroidal ecdysone agonist, RH-2485, was determined on Helicoverpa armigera larvae under laboratory and field conditions. RH-2485 sprays (25–150 μg/ml) caused premature, incomplete molting in 28–94% of the treated 2nd instar larvae within 24 h. Topical application of RH-2485 to 6th instar larvae (30–200 ng/larva), caused premature molting in 3-83% within 24 h, and 66–96% in 15 days, post-treatment. The eD10, eD50 and eD90 for 24 h were determined as 37, 100 and 250 ng/larva, and for 15 days as 0.65, 7.50 and 100 ng/larva, respectively, according to the corrected trend line. Ingestion of 0.1–1000 ng RH-2485 by 6th instars caused premature molting in 10–65% of the larvae in 24 h and 8–64% in 15 days. Field trials indicated that RH-2485 sprays at 50–150 g (AI)/ha decreased the larval population of boll worms by 68–73%. Correspondingly, the injury by the pest to bolls and apical buds of the cotton plants was decreased by 54–65% and 57–77%, respectively.
 
Article
Several plant viruses are highly contagious and their effects on plants are often drastic. Many seriously reduce crop yield and quality. Numerous disorders are caused or triggered by viruses and a great deal of money is spent on preventing virus diseases from becoming disastrous. Losses caused by any disease cannot be measured directly because potential yield and damage are so variable. Experimental assessment of the losses attributable to virus diseases is particularly difficult because it is extremely hard to prevent contamination of healthy control plants and inoculation under vector-proof conditions may not reflect accurately what happens under natural conditions. The prevalence of the causal viruses or the extent of attack are not reliable guides to the amount of damage caused; this contrasts with the situation with invertebrate pests where losses are usually related to the population densities of the pests. In a few virus diseases, attempts have been made to establish the relationships between final yield loss and certain indicators such as incidence, severity and duration of disease, or between combinations of these, but the relationships seem to be valid only under strictly defined conditions. The main aims of this work have been to estimate actual losses inflicted on a farmer's crop or upon a larger area, to predict the magnitude of losses that may develop and to decide what control measures are justified. In practice, assessment of loss has been extrapolated from trials in which various infection severities and infection times have been used to simulate natural situations. Yield improvements with virus-free propagation material have sometimes been used for loss assessment. Losses caused by virus diseases depend on the cultivar involved: evaluation of the resistance of different cultivars may be further improved by assessing the effects of viruses on yield rather than by assessing the severity of symptoms. Losses is strictly financial terms are influenced by fluctuating prices for crop products and are even more difficult to asses, let alone to predict, than are losses of yield. Nevertheless, a better understanding of the way in which virus disease epidemics develop, and of the resulting biological and economic losses, is essential for effective crop protection, whether on individual farms or on a national scale.
 
Ultrastructure of B. subtilis strain 3A25. A: DIC image of the strain prior to fixation, several bacterial cells are undergoing division (arrow). B: brightfield image of fixed and Toluidine Blue O stained bacteria. CeG: TEM images: C: brighter areas inside the body (arrow) of a cell in division, surrounded by a bacterial "cell wall", D: different sectioning angles and brighter areas inside (arrow), E: longitudinal section, F: cross section, note the highly organized structures in vicinity of the cell, likely representing flagella (arrows), and G: cross section with longitudinally sectioned flagellum (arrow). H: longitudinally sectioned flagellum. Bars: A-B, 10 mm; C-G, 500 nm; H, 100 nm. 
Brassica juncea characteristics during different treatments. A) chlorophyll content, B) leaf area, C) shoot length, D) root length and E) number of secondary roots as a consequence of different treatments: treatment 0, control: plants without ozone or B. subtilis 3A25; treatment 1, plants treated with B. subtilis 3A25; treatment 2, plants treated with ozone (150 ppb of ozone for 30 min twice a day for a period of 10 days); treatment 3, ozone and B. subtilis 3A25 as foliar spray; treatment 4, ozone and B. subtilis 3A25 on soil. The bars represent mean values AE standard deviation (SD), significantly different values (P < 0.001) are marked with individual letters (aee), the same letter indicates no significant difference in means and SD. 
Article
Strain 3A25 was isolated from Indian soil during a screening study for new plant protecting candidates. The present study further characterized this strain regarding its species identity, cellular ultrastructure and potential for protecting Brassica juncea against exposure to ozone. The strain was identified as Bacillus subtilis by 16S rDNA sequencing. Transmission electron microscopy revealed that strain 3A25 had intact bacterial flagella, endospores were found only occasionally. The growth-promoting capacity of strain 3A25 on B. juncea seedlings was investigated in a series of treatments with or without ozone stress in open top chambers. Chlorophyll content, shoot length, root length and leaf area were significantly increased by the treatment with B. subtilis 3A25. The ozone treatment (150 pbb) had a significant inhibiting effect on the development of B. juncea, however, the number of secondary roots was increased. Application of B. subtilis 3A25 either as foliar spray or directly on the soil significantly reduced the negative ozone effect, indicating that this strain has capacities in plant protection against environmental stress.Highlights► Bacillus subtilis 3A25 has growth-promoting capacities in Brassica juncea seedlings. ► Ozone reduces chlorophyll content, leaf area, shoot and root length in B. juncea. ► Number of secondary roots is enhanced in B. juncea after ozone exposure. ► B. subtilis 3A25 treatment protects B. juncea seedlings from ozone damage. ► B. subtilis 3A25 has intact flagella, endospores are found only occasionally.
 
Article
Pencycuron (tradename Monceren®, a fungicide developed specifically to control Rhizoctonia) was evaluated for in vitro growth inhibition of wheat pathogenic Rhizoctonia spp., Gaeumannomyces graminis var. tritici and Pythium spp., and for control of wheat root diseases in greenhouse trials. In the greenhouse, pencycuron inhibited binucleate Rhizoctonia, R. oryzae, or R. solani in vitro and reduced Rhizoctonia root rot. Pencycuron also inhibited G. graminis var. tritici strains in vitro and slightly reduced take-all disease in the greenhouse. Moreover, pencycuron seed treatment protected plants against a disease mixture of Rhizoctonia root rot and take-all. Pythium spp. were not inhibited by pencycuron in vitro. Pencycuron did not adversely affect seedling emergence, nor did it inhibit rhizosphere colonisation by Pseudomonas fluorescens biocontrol strain 2-79. Combined application of the fungicide and strain 2-79 to seed was more effective than either treatment alone for controlling disease.
 
Article
Yield loss in highland banana caused by the banana weevil, Cosmopolites sordidus, was studied in field trials in Uganda. Weevils were released at the base of banana mats 9 months after planting. Weevil populations, corm damage, plant growth and yield were assessed over four crop cycles. The effect of damage was greater on bunch weight than on plant growth and rate of development. Yield loss increased with crop cycle and ranged from 5% in the first cycle to 44% in the fourth cycle. The cumulative effect of heavy damage sustained over several crop cycles resulted in greater reduction in bunch weight than that inflicted by similar levels of damage in a single cycle. The data suggest that C. sordidus damage is a leading cause of highland banana decline and disappearance in central Uganda.
 
Article
Emergence of sh-2 sweet corn seedlings from soil infested with Pythium ultimum at three diverse field sites was greatly improved either by coating the seed with Pseudomonas aureofaciens AB254, or by biopriming the seed with this bacterium. Both treatments were equivalent to the control provided by treating the seed with the fungicide metalaxyl. In controlled-environment tests, emergence of sweet corn seedlings in soil that was autoclaved or naturally infested with P. ultimum increased with soil temperature from 5 to 24°C. Low soil temperatures enhanced the impact of P. ultimum on sweet corn seed, with the most severe decay of untreated seed at soil temperatures between 5 and 17°C. Bio-priming and seed coating with P. aureofaciens AB254 increased seedling emergence compared with that of untreated seed at all temperatures, even though bacterial multiplication did not occur at low temperatures. Increasing P. ultimum inoculum density from 0 to > 1800 propagules per gram (p.p.g.) decreased emergence from untreated seed from 90 to 11%. There was no corresponding reduction in emergence in soil with inoculum densities >159 p.p.g. when the seed was bio-primed or coated with bacteria. Decay was more severe with increasing soil water potential from −0.07 to −0.01 MPa. At low and intermediate soil moisture, both bio-priming and bacterization with P. aureofaciens AB254 improved seedling emergence compared with untreated seed, but at the highest soil moisture only the bio-priming treatment provided protection.
 
Article
The chemical stability of cypermethrin was studied at different water pH values. Four different treatments were used to study the stability of cypermethrin, namely canal water (pH 8.38), distilled water (pH 6.20), phosphoric acid-treated canal water (pH 6.00) and propionic acid-treated canal water (pH 6.00). Insecticide-treated water samples were allowed to stand for 1, 4 and 24 h in darkness before extraction. Presence of cypermethrin was determined by gas-liquid chromatography. The highest percentage of hydrolysis of cypermethrin 24 h after treatment was found in canal water. Cypermethrin also degraded in distilled water, but at a slightly slower rate than in the canal water. Only slight losses were found to take place after 1, 4 and 24 h in the canal water treated with phosphoric acid or propionic acid. Because a pH value > 6.00 is likely to reduce the stability of cypermethrin, farmers using the King Abdallah Canal water should adjust the pH to 6.00 with phosphoric or propionic acid before mixing cypermethrin.
 
Article
Field experiments and bioassay tests were carried out to evaluate the relative response of the crops, tossa jute (Corchorus olitorius L.) and okra [Abelmoschus esculentus (L.) Moench], and their associated weeds to pre-emergence application of pendimethalin at 0.33, 0.66, 0.99, 1.32 kg ai ha−1 and a pendimethalin+atrazine tank mixture at 1.32+2.05 kg ai ha−1. Bioassay tests were carried out using herbicide solutions of corresponding concentrations and herbicide-treated soil. Field application of pendimethalin at ⩾0.66 kg ai ha−1 and the herbicide mixture in both crops effectively controlled most seedling weeds including Rottboellia cochinchinensis. Euphorbia heterophylla and Calopogonium mucunoides, which persisted from 2 weeks after treatment (WAT) were not controlled. Herbicide application during crop establishment markedly inhibited the growth of both seedling weeds and crops. The mixture caused the highest weed and crop injury. Pendimethalin at 0.33 kg ai ha−1 had minimal effect on these crops. Weed growth, weed tolerance of herbicide treatment and crop seedling injury were higher in tossa jute than that in okra, under the conditions of this study. The use of low pendimethalin doses in an integrated weed management system will ensure effective control of seedling weeds, and prevent crop injury and residue accumulation in edible plant produce.
 
Article
Experiments were conducted in controlled growth cabinets to examine the effect of air temperature (16°C, 22°C, 35°C) or relative humidity (RH, 45%, 70%, 95%) on 14C-glyphosate distributions in Desmodium tortuosum and bio-efficacy. Uptake and translocation of 14C-glyphosate were significantly higher at 22°C or 95% RH than 16°C and 35°C or 45% and 70% RH at all harvest times. These values were also significantly higher when influence of temperature or RH recorded when the effects across harvest times (6, 24, 48, 72 h) were averaged. Further, uptake and translocation were significantly higher at 48 h than the other harvest time when the effects across temperatures (16°C, 22°C, 35°C) were averaged. Maximum translocation was obtained at 72 h harvesting time when the effects of RH (45%, 70%, 95%) were averaged. When glyphosate was sprayed to beggarweed, the maximum foliar damage was observed 19% at 22°C or 35°C and 23% at 95% RH. Bioefficacy results were similar to 14C-glyphosate translocation at 22°C and 95% RH. The results indicated that temperature or RH influenced the absorption process of glyphosate and the optimum temperature and relative humidity for Desmodium control were 22°C and 95% RH.
 
Article
The purpose of this study was to examine the effect of several management tactics and Sitophilus zeamais Motschulsky (maize weevil) on fungal species composition and abundance on stored corn (maize). The most abundant fungi isolated from Pioneer hybrids 3378 and 3320 were Fusarium sp., Penicillium spp., Rhizopus sp., Aspergillus glaucus and A. flavus. High temperature (36 °C) inhibited the growth of Fusarium sp., Penicillium spp., Rhizopus sp. and A. flavus, while the growth of A. glaucus increased. Low initial kernel moisture content (9.7%) appeared to inhibit the growth of some fungi (Fusarium sp. and A. glaucus) while the growth of others (Penicillium spp. and A. flavus) increased. Surface disinfection with bleach reduced populations of Penicillium, Rhizopus, A. glaucus and A. flavus, while permitting an increase of Fusarium. Biotic factors also exert considerable control over fungal populations. Hybrid selection affected all major species except Fusarium. The mere introduction of maize weevils, even when killed within 24 h by malathion, increased the abundance of Penicillium spp. and A. glaucus.
 
Article
Only recently, due to a major reduction of broad-spectrum insecticide use in transgenic (Bt) cotton in China, plant bugs (Heteroptera: Miridae) have emerged as key pests of this crop. To determine their species composition and seasonal activity at various locations nationwide, field surveys were carried out between 2002 and 2006, using sweep-net samples and visual observation. Surveys were conducted in three major cotton-growing regions: Changjiang River, Yellow River, and Northwestern Region. The mirid complex on Bt cotton basically consisted of five different species, with Lygus lucorum, Lygus pratensis, and Adelphocoris suturalis most commonly encountered. L. lucorum and A. suturalis were the dominant species in the Changjiang River and Yellow River Region, while L. pratensis was the most common species in the Northwestern Region. The various mirid species were found in cotton fields throughout the cotton-growing season, usually with great population densities during the squaring and flowering stages. Peak mirid abundance ranged from 50 to 200 per hundred plants. Given the comparatively low economic thresholds for mirids (approx. 10 individuals/100 plants), these insects constitute serious pests in all cotton-growing regions of China. This paper suggests that L. lucorum, L. pratensis, and A. suturalis should be treated as the main targets for developing pestiferous mirid forecasting and management strategies, which would be defined at or prior to the flowering and squaring stages of cotton in China.
 
Average (AESEM) number and percentage of stemborer life stages parasitized and dead per plot in Lambwe and Homabay. Means marked by different letters within a site and mortality factor are significantly different (P < 0.05, t-test). The unmarked means are not significantly different. 
Average (AESEM) time (min) spent in and number of entries of female C. sesamiae wasps into the treatment and control arms of the four-arm olfactometer (n ¼ 30). Averages marked by different letters within a graph and column are significantly different (P < 0.05, t-test). Unmarked bars are not significantly different. 
Article
We assessed the non-target effects of a habitat management system (‘push–pull’) on maize stemborer specialist natural enemy activity and soil Collembola. Two study sites in western Kenya were sampled. There were two treatments at each site, maize monocrop and ‘push–pull’. The latter comprised an intercrop of maize and Desmodium, Desmodium uncinatum Jacq., with Napier grass, Pennisetum purpureum (Schumach), as a trap crop planted around the edge of the plot (spaced 1 m from main crop). Trichogramma spp. were recovered from stemborer eggs while Cotesia sesamiae and Cotesia flavipes were recovered from stemborer larvae, and Dentichasmias busseolae from pupae. Mean number of eggs parasitized was significantly higher in the maize monocrop than in the ‘push–pull’ plots however proportions parasitized did not differ between the two systems. The number of larvae and pupae parasitized and dead from causes other than parasitism similarly did not differ between cropping systems. Proportions of larvae and pupae parasitized were significantly higher in the ‘push–pull’ than in the monocrop plots, indicating that the activity of larval and pupal parasitoids was enhanced. C. sesamiae female wasps were attracted to the volatiles from Desmodium flowers but not those from the leaves in a four-arm olfactometer bioassay. A total of 1530 individual Collembola in seven families were recovered from the plots. The ‘push-pull’ strategy did not have any significant effect on Collembola abundance and dominance. The factors underlying these observations and their implications are discussed.
 
Article
Relative abundance of terrestrial, non-target invertebrates in savannah grassland was monitored following large-scale field trials using the insect growth regulator (IGR) diflubenzuron applied as barrier treatments for control of the migratory locust in Madagascar. Identical sampling techniques were employed to monitor invertebrates at two different trial sites, separated by about 300 km; one treated with IGR barriers over an area of 20 km2 in 1993 and the second, treated similarly over an area of 5 km2 in 1994. Data were collected for more than 300 species from over 120 families and 17 orders. Faunal composition of sweep net catches was similar at the order and family level for the two areas, but quite different at the species level. The majority of invertebrates sampled either occurred in numbers too small to be evaluated statistically or showed no evidence of effects even within spray barriers over a 3 month period following spraying. However, depending on timing of spraying, relative abundance of both caterpillars [Lepidoptera] and non-target grasshoppers [Acrididae] declined within spray barriers following treatment and remained low for several months. Adverse impacts on spiders [Araneae] (particularly Salticidae), crickets [Orthoptera; Gryllidae] and bugs [Heteroptera] could not be discounted. Inter-barrier spaces, 500 m wide, acted as true refugia, with no evidence of effects of spraying on fauna within the middle 300 m of these areas. Diflubenzuron barriers appear to be relatively safe to non-target fauna in the short term, by comparison with other methods of locust control. However, with barriers spaced at 500–600 m, the severe decline in abundance of caterpillars and of non-target grasshoppers within spray barriers cannot be dismissed as ecologically insignificant for the treated area as a whole and further monitoring of these insects should accompany future diflubenzuron barrier use. The technique seems likely to be environmentally acceptable, but this can only be confirmed after evaluation of longer-term impacts.
 
Article
Lygus lucorum Meyer-Dür, Adelphocoris fasciaticollis Reuter and Adelphocoris lineolatus (Goeze) (Hemiptera: Miridae) are important secondary insect pests in cotton fields in northern China. The seasonal dynamics of their mixed populations on a transgenic variety expressing the insecticidal Bt protein Cry1A, and a cotton line expressing proteins of Cry1A and CpTI (cowpea trypsin inhibitor gene) were compared to seasonal dynamics on similar but non-transgenic varieties from 1998 to 2001. No significant differences were detected between population densities of these bugs on unsprayed normal cotton and unsprayed transgenic cotton. However, mirid damage on unsprayed transgenic cotton was significantly higher due to a reduced number of insecticide sprays against Helicoverpa armigera compared with the number of sprays in the normal cotton. This suggests that the mirids have become key insect pests in transgenic cotton fields, and that their damage to cotton could increase further with the expansion of the area planted to transgenic cotton if no additional control measures are adopted.
 
Article
This study was designed to test the hypothesis that habitat alteration with intensive herbicide (glyphosate) treatment would adversely affect the small mammal community in apple orchards. Multiple applications of herbicide were applied to the total orchard floor in two experimental orchards, and this same herbicide regime was applied in a 2-m-wide strip within tree rows only in a third orchard. Intensive sampling of montane vole (Microtus montanus), deer mouse (Peromyscus maniculatus), and northwestern chipmunk (Eutamias amoenus) populations was conducted in replicate control and treatment blocks of apple orchards at Summerland, British Columbia, Canada from 1983 to 1986. Average abundance of voles declined by 53% to 73% on treatment compared to control blocks after the first herbicide application. Vole populations were consistently reduced in response to the herbicide treatment, with average abundance ranging from 2.8 to 28.0 times higher on control than treatment blocks. Voles declined to, or near, extirpation in all orchards during the winter of 1985–1986. Either deer mouse and northwestern chipmunk populations were significantly higher on treatment than control blocks or there was no difference in abundance after the start of the herbicide applications. The average abundance of deer mice ranged from 1.3 to 11.1 times higher, and that of chipmunks ranged from 1.8 to 13.3 times higher, on treatment than control blocks. The high numbers of deer mice and chipmunks on treatment blocks were composed mainly of resident animals. There were no significant differences in biomass of small mammals between control and treatment populations in summer and winter periods in two out of three orchards. There appears to be a ‘compensatory response’ in this small mammal community whereby deer mice and northwestern chipmunks have essentially ‘replaced’ the montane vole on treatment blocks in an orchard agroecosystem. The quality of the altered habitats seemed sufficiently high to support these populations at comparable or higher levels than on controls. The species diversity of plants and animals in orchard agroecosystems should be investigated to determine their role as part of a mosaic of natural and agrarian habitats.
 
The universal cassette (pBSK-trpC promoter–terminator) cloning plasmid. Electrophoresis of 1 ml of the plasmid DNA isolated from five independent heatshocked transformed bacterial isolates (1–5) through a 1% (w/v) agarose gel at 50 V for 40 min; lane #2, 1 ml of the non-spliced native pBSKD vector DNA; M, molecular marker (1 kb ladder).  
RT-PCR analysis confirms oahA gene expression in C. coccodes transformants. RT-PCR analysis of cDNA from mycelia of eight independent oahA transformants and wild type of C. coccodes. The analyses were performed with the oahA and histone H4 primers shown in Table 1. Histone4 (H4) was used as a reference gene. The negative control of (À)RT (RNA samples without the reverse transcriptase) was clear (data not shown). wt, wild type; oahA, oahA transformants 1–17; PL, plasmid containing the oahA gene (positive control); NTC, no template control; gDNA, genomic DNA of C. coccodes. Fragment size: cDNA, 200 bp; gDNA, 250 bp.  
Article
Abutilon theophrasti (Malvaceae) is a widely distributed weed that infests a variety of agricultural crops. Cotton is in the same botanical family, precluding the use of selective chemical herbicides. An Abutilon-specific pathovar of Colletotrichum coccodes has been considered as a potential bioherbicide for the selective control of A. theophrasti. An evolutionary balance between microorganism and weed maintains a relatively low virulence of the microorganism, such that it does not destroy its food supply by rapidly killing its host. We overexpressed the oahA (oxaloacetate acetylhydrolase) gene in C. coccodes to increase oxalate production, as oxalate inhibits plant-defensive callose synthase by chelating calcium, an obligate co-factor of this enzyme. C. coccodes oahA transformants acidified the surrounding medium, an indication of acid production by hydrolysis of oxaloacetate. Less callose was seen visually around lesions caused by C. coccodes oahA transformants than the wild type in preliminary experiments, but this was not biochemically quantifiable. Further optimization might be obtained through gene stacking, or the addition of multiple virulence genes to this potential biocontrol agent.
 
Article
Safflower (Carthamus tinctorius L.) is an important oil seed crop with growing importance in many countries around the world. However, safflower fly (Acanthiophilus helianthi Rossi) is one of the main limiting factors to expand the production area of the crop in several countries. Since host plant-resistance is the most efficient method for pest management, we evaluated a germplasm of wild accessions (Carthamus oxyacanthus Bieb.) with mostly brown–black seed coat color along with some white-seeded cultivated safflower genotypes for resistance to safflower fly. The results showed that there was a significant difference between two species for safflower fly damage with all cultivated genotypes being susceptible. However, for the accessions of C. oxyacanthus, a wide range of resistance was observed. In a choice experiment and natural infestation, 35.3–78.9 percent of heads per plant were infested in genotypes of C. tinctorius while for the accessions of C. oxyacanthus this was much smaller and ranged from 1.6 to 13.6%. In addition, percentage of seed yield loss per infested plant was more drastic in cultivated safflower (29.0–72.8%) than the wild accessions (0.0–21.4%). In the no-choice experiment, fly population was dramatically decreased in the wild accessions due to larval mortality and possibility of antibiosis. There was a strong relationship between brown–black seed coat color and resistance to safflower fly indicating the possibility of using this trait in breeding programs of safflower to develop fly-resistant cultivars.
 
Article
Acanthoscelides obtectus Say (Coleoptera, Bruchidae), is a cosmopolitan pest that damages its host plant, the kidney bean (Phaseolus vulgaris L.) in the field and during storage. The use of aromatic essential oils from Labiatae, Umbelliferae and Lauraceae was investigated. In addition to a fumigant toxic effect on adult insects, inhibition of reproduction through ovicidal and larvicidal effects was also observed. These actions might be combined to improve the management of this bruchid: essential oils of Rosmarinus officinalis, Thymus vulgaris, T. serpyllum, Ocimum basilicum and Cinnamomum verum were very effective and completely controlled the biological development of this insect.
 
Article
Following failures to control the European Red Mite (Panonychus ulmi) using METI-acaricides in some apple orchards in the south of France, resistance to fenazaquin and tebufenpyrad was studied under laboratory conditions. Resistance ratios ranged from 19.8 to 28.8 and from 16.8 to 39.8, respectively, for fenazaquin and tebufenpyrad when compared to the most susceptible of the 2 reference populations. An examination of bioassays responses showed that resistance was higher with tebufenpyrad than with fenazaquin. The recommended field rates for these compounds corresponded only to the LC95 for fenazaquin and the LC70 for tebufenpyrad. These results confirm resistance development to METI-acaricides in ERM field populations and suggest it could be responsible for reduced persistence of mite control and in some cases for control failure in apple orchards.
 
Article
The influence of leaf surfaces of different host plants on the biology and life table parameters of the predacious mite, Agistemus exsertus Gonzalez was studied in the laboratory. A. exsertus successfully developed and reproduced on all tested plant leaves. Smooth, glabrous pear leaves accelerated the development of A. exsertus and showed the shortest mean generation time. Slightly rough, slightly hairy leaves of mulberry and acalypha were the most suitable surface for oviposition of the predator. These leaves exhibited the highest fecundity and net reproductive rate. On the other hand, leaves of rough, pubescent apple and scabrous, bristly lantana were the least suitable surface for oviposition of A. exsertus. They showed the lowest fecundity and net reproductive rate. Acalypha leaves exhibited the highest intrinsic rate of increase for the predator, whereas lantana leaves showed the lowest value. This difference in the predator response to leaf surfaces of host plants should be considered to enhance the role of the predator in biological control programs.
 
Article
The tarsonemid mite, Phytonemus (Tarsonemus) pallidus ssp. fragariae (Zimmerman), is a serious pest of strawberry throughout much of Europe and North America. Many of the plant protection products previously effective against the mite, which causes stunting and distorting of leaves and buds, reducing fruit yield and quality, are no longer available. Finding alternative acaricides for control is a priority. In two field trials, we tested 9 foliar applied plant protection products to determine the efficacy for control of Phytonemus pallidus, and to assess their effects on natural enemies. The products tested as foliar applications (dose ha−1) were; abamectin 18 g/l EC (250, 500, 750, 1250 ml), tebufenpyrad 20% WP (500 g), fenpyroximate 51.3 g/l SC (1.0 l), bifenazate > 90% WP (400 ml), spiromesifen 24 g/l SC (500 ml), acequinocyl 15.8% SC (1.0 l), spirodiclofen 240 g/l SC (400 ml), etoxazole 110 g/l SC, and the surfactant, Silwett L-77 (Heptamethyltrisiloxane 0.05% (50 ml)). Effective products were used in admixture with the surfactant to investigate potential increased efficiency against P. pallidus. In each experiment, two applications were applied to plants previously inoculated with P. pallidus.None of the products controlled the mite effectively when applied alone, but the addition of Silwett L-77 greatly improved control of the pest, particularly in combination with abamectin, etoxazole and tebufenpyrad. These treatments reduced P. pallidus mite numbers by 98, 85 and 80%, respectively. Many of the acaricidal products that are normally active against other species of Acari probably fail to control P. pallidus because of the inaccessibility of the mite within the fold of the young leaflets. In addition, the leaves of strawberry plants are more waxy and hairy than most other crops and are difficult to wet. Hence, significant improvement in efficacy of some products can be achieved if mixed with the silicone surfactant.
 
Mortality (%) of Panonychus ulmi on apple leaves treated with detergents
Individuals of Panonychus citri dislodged and mortality (%) on lemon leaves treated with detergents
Article
Two laboratory experiments using a leaf-dip technique evaluated the effect of two detergents, Quix and Nobla, on Panonychus ulmi and P. citri. Fenazaquin 0.01% a.i. was used on P. ulmi as a standard. Mortality increased with higher concentrations in both mite species. In addition, detergent treatments also dislodged P. citri mites from leaves. Dislodged + dead mites varied between 31.7% (Quix 0.25%) and 91.3% (Nobla 0.45%), in comparison with 22% in the control. These results suggest the need to evaluate the use of detergents against both mite species in field orchards.
 
Article
Studies were carried out between 1987 and 1989 in the East Mediterranean region of Turkey on Tetranychus cinnabarinus control in strawberry fields. Acaricides that could be recommended for red spider mite control were determined and the effects of acaricide application at early fruit stage on the population during the season were studied, as were variations in red spider mite populations. Early fruit stage applications of dicofol, dicofol plus tetradifon or one of the other effective acaricides tested could control mites throughout the fruiting season. Bromopropylate, azocyclotin, dicofol and dicofol plus tetradifon controlled red spider mites; however, fruits should not be picked sooner than 1 week after application.
 
Article
Accelerated microbial degradation is the name commonly given to the phenomenon associated with a significant increase in the rate of degradation of a pesticide in soil following a previous application of the same pesticide and also to the closely related phenomenon involving an unexpectedly rapid degradation of a pesticide following a previous application of another pesticide, usually of similar chemical structure. It apparently is caused by an adaptation of one or more species of microorganism present to metabolize the pesticide. In the late 1940s it was recognized that repeated applications of 2,4-D accelerated its degradation. Studies done in the 1970s and 1980s revealed that many pesticides in use were susceptible to the phenomenon and that it was reducing the efficacy of a number of commercial products especially those for which applications at seeding time were expected to provide prolonged pest control. Further work since that time has shown the dynamic nature of the phenomenon as a number of pesticides which were previously shown to be unaffected are now susceptible. The phenomenon can result in significantly reduced crop yields and coping with it usually involves additional costs. In the following manuscript we give an overview of this phenomenon, its basis and possible solutions; and attempt to predict how should biogeography factors and tropical conditions influence the phenomena.
 
Article
Metam-sodium (MS) and dazomet (DAZ) are soil fumigants that generate methyl-isothiocyanate (MITC) in soil. The latter effectively controls soilborne plant pathogens. Recently, we have found that repeated applications of MS yield less effective pathogen control. Soil samples collected from 12 field sites in Israel without (nonhistory) or with (history) previous applications of MS or DAZ were tested for MITC generation and dissipation. Accelerated MITC degradation in history soils, as reflected by a sharp reduction in the concentration×time (C×T) values and half-lives of MITC, was evident in most of the tested history soils. Exposure to MS and DAZ in those soils resulted in a significant reduction in Verticillium dahliae, Sclerotium rolfsii and Fusarium oxysporum f. sp. radicis-lycopersici mortality compared to exposure in nonhistory soils. The chemical and biological assays were well correlated. This is the first report of accelerated degradation of MITC resulting from repeated applications of DAZ. MITC was rapidly degraded in soils which had been previously treated with either MS or DAZ, indicating induced cross-accelerated degradation with both fumigants. In two field soils, accelerated degradation of MITC capacity was still evident for 18 to 30 months after treatment. This study suggests that accelerated degradation of MITC is a likely cause of the poor pathogen control observed in commercial potato and peanut fields upon repeated application of the fumigants MS and DAZ, and emphasizes the need for rational use of pesticides to maintain their efficacy.
 
Article
In laboratory incubation studies with 32 farm soils, the initial half-life of freshly-applied phorate ranged from less than 1 to more than 16 weeks. Accelerated degradation was stimulated by a single application of the recommended dose and occurred most readily at pH levels 7.4. It is recommended that the degradative properties of soils are established before insecticide treatments are selected.
 
Article
The resistance to grasshoppers of several legumes currently under consideration as green manure crops was assessed. Four species of legumes plus spring wheat were evaluated for grasshopper population density and feeding injury at the Agriculture Canada Research Station at Swift Current, Sask. The trial included chickling vetch (Lathyrus sativus L. cv. NC8-3), Tangier flatpea (L. tingitanus L. cv. Tinga), pea (Pisum sativum L. cv. Sirius), black lentil (Lens culinaris L. cv. Indianhead) and wheat (Triticum aestivum L. cv. Leader). The four major pest species of grasshoppers in Saskatchewan were present in all plots. Melanoplus sanguinipes (Fabr.) was the predominant grasshopper species followed by Camnula pellucida (Scudder), M. packardii (Scudder) and M. bivittatus (Say). Wheat () had a significantly higher (P < 0.05) number of grasshoppers during the study than did the lentil () and pea (), but not more than chickling vetch ) or Tangier flatpea (). The number of wheat plants () which suffered damage was also significantly higher than all legumes. Of the legumes, the chickling vetch () and the flatpea () were damaged significantly more often than the lentil () and the pea (). Leaf defoliation was rated from 0 to 5, where 1 represented less than 25% leaf destroyed, 2 = 25–50%, 3 = 51–75%, 4 = 76–99% and 5 = 100%. Comparisons of foliar damage showed that wheat leaves () were significantly more damaged than all legumes. Chickling vetch () and Tangier flatpea () were significantly more damaged than both the lentil () or pea (). Preference tests in the laboratory, using M. sanguinipes, confirmed earlier damage studies when grasshoppers were presented with wheat, lentil and pea. Field trials, also with M. sanguinipes, showed that the biotic potential of grasshoppers was highest on wheat () followed by lentil () and pea (). Thus, the use of resistant legumes could reduce the overall need for insecticides because these crops will not likely become epicentres of grasshopper outbreaks.
 
Article
Highly significant relationships between the percentage of leaves showing Psylliodes chrysocephala (L.) feeding scars and the mean number of larvae per plant during autumn, were established from 457 fields (over five different years) in England and Wales, and used to define an index of leaf scarring as an alternative assessment method for control decisions. The index was tested in conjunction with autumn samples using datasets from 786 fields (six years). An action threshold of 50% leaves scarred resulted in similar treatment advice to the current plant dissection method in over 98% of cases. During spring, the relationship between percentage leaves scarred and mean number of larvae per plant was not consistent between years and the index cannot be used for population assessment at this time of year.
 
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Bhagirath S Chauhan
  • The University of Queensland
Murray B. Isman
  • University of British Columbia - Vancouver
Charles Wilson
  • WORLD FOOD PRESERVATION CENTER LLC®
Samiyappan Ramasamy
  • Tamil Nadu Agricultural University
Yigal Elad
  • Agricultural Research Organization ARO