Peter Baur

CropPromotion

The loss of important contact herbicides like paraquat opens opportunities for more potentially sustainable solutions demanded by consumers and organizations. Frequently, for adequate weed control, the alternatives to classical synthetic products need well-defined and executed labels and even more detailed use descriptions. One novel candidate with...

English abstract by Peter Baur: After the German reunification I found 1991 Albert Wigand's book on "Intercellularsubstanz und Cuticula" in an antiquarian university bookshop in the north-east German city of Rostock. This book from 1850, published by Vieweg & Sohn, Braunschweig, is probably the first book about the cuticular membrane across species...

High biological diversity particularly of trees and other plants is an obvious feature of tropical rainforests. This applies also to pests and pathogens. For fungi, bacteria, algae, and some other microorganisms the tropical conditions are described as paradise, and rapid degradation of organic matter is generally postulated in the literature about...

Basic features and inflorescences of Coccoloba gigantifolia were described in 2019 only, after first documentation by academia 1982 at Borba, Madeira river basin, one of two main sites so far. Here we report about vegetative life cycle, leaf and other characteristics of more than 10 trees from a new site, east of the Mamori Lake, at 70 km distance...

Basic features and inflorescences of Coccoloba gigantifolia were described in 2019 only, after first documentation by academia 1982 at Borba, Madeira river basin, one of two main sites so far. Here we report about vegetative life cycle, leaf and other characteristics of more than 10 trees from a new site, east of the Mamori Lake, at 70 km distance...

Basic features and inflorescences of Coccoloba gigantifolia were only described 2019 after first documentation by academia 1982 at Borba, Madeira river basin, one of two main sites so far. We report here about vegetative life cycle, leaf and other characteristics of more than 10 trees from a new site, east of the Mamori Lake, in 70 km distance and...

Only a limited number of contact herbicides exist in agricultural production. While systemic herbicides are more efficient also at suboptimum spray coverage with long-lasting weed control, contact herbicides provide also several advantages. There is no translocation to fruits or roots of plantation and other crops, low risk for resistance developme...

BACKGROUND Ever since the beginning of agriculture, yields have been threatened by weeds. Chemical control is far more effective and economical than other weed control methods. The frequent use of herbicides has led to environmental and human health concerns, causing the ban of several herbicides and challenges for the future of important actives l...

Pre-emergence herbicides are taken up by seeds before germination and by roots, hypocotyls, cotyledons, coleoptiles or leaves before emergence, whereas post-emergence herbicides are taken up primarily by foliage and stems. Most modern pre-emergence herbicides are lipophilic, but post-emergence herbicides may be lipophilic or hydrophilic. The metabo...

Impact of Physicochemical Parameters on Fungicide Activity Analysing the pattern of physicochemical properties of all fungicides registered in the latest edition of “The Pesticide Manual” suggests the following properties of a fungicide for good performance: a relatively high lipophilicity (logP between 2.5 and 4.5), a water solubility in the rang...

For an effective spray application, several partial processes have to be optimised, the most significant being spray retention, macroscopic coverage, microscopic contact of liquid and deposit to the surface, uptake from spray and deposit, and finally, long term surface stability of the agrochemical. While uptake depends often on the interaction of...

More than three decades after the discovery of the tree with by far the largest leaves, the first description as Coccoloba gigantifolia and a systemic classification was recently made. Surprisingly little had become known about its biology during this long period, which is related to the rare occurrence of this tree. For a long time, it was only kn...

Reporte sobre un extraordinario árbol con enormes hojas simples en forma de paraguas. Más de tres décadas después del descubrimiento del árbol con las hojas más grandes, se hizo recientemente su primera descripción como Coccoloba gigantifolia y una clasificación sistémica. Sorprendentemente poco se conocía sobre su biología durante este período, lo...

For an effective spray application, several structural features of the leaf surfaces have to be taken into consideration. The most significant parts of the surfaces are the plant cuticle and the epidermis. While leaves appear often and typically flat both are rarely arranged in plane surfaces. Just the opposite has been evolved since plants occupie...

In this study, coleoptile penetration of two radiolabelled systemic active ingredients with different physicochemical properties, imidacloprid and 1-napthylacetic acid (NAA) was measured. Applications were made to the aerial and non-aerial parts of the coleoptile of wild oat (Avena fatua) plants. The non-aerial coleoptile portion was shown to be a...

Some surface features of grasses were already touched in chapter 7 (leaf). Chapter 11 deals with grass surfaces in detail. Light and SEM pictures show different grass trichomes (the indumentum); also, papillae of various species are documented. A short paragraph deals with stomata. Cork and silica cells are often regarded as identification criteria...

Our knowledge of fertilisation in grasses resulted in the great achievements of the hybrid technology in maize, rice and other grass crops. Increased yields contribute to the high food and feed demand of growing human societies. The organs and tissues involved in fruit development ‐ nucellus, ovule and embryo sac ‐ were modified in evolution to qui...

The non-aerial hypocotyl is an exceptional fast pathway for the uptake of soil-applied pre-emergent herbicides or systemic actives with soil mobility after release from coated seeds. The presence of charged groups at the interface of the non-aerial hypocotyl to the environment and its role for the penetration of likewise charged agrochemicals have...

The present invention relates to compositions that include a combination of one or more pesticides and one or more adjuvants.

Recently, introduction of a novel methylated seed oil (MSO) / non-ionic surfactant (NIS) blend with an NIS content in excess of 50% came to the adjuvant market. This unique blend, subsequently called NOVAD, has an NIS component of polyglycerol ester (PGE), which is a co-polymer of glycerol and at least one di-carboxylic and one monocarboxylic acid,...

Products based on co-polymers of glycerol, at least one dicarboxylic and one monocarboxylic acid, act as dispersing agents and/or adjuvants in various soluble liquid formulations. Because of the hydrophilicity of the polyglycerol chain, use of these products is typical in water-based formulations. Presenting novel derivatives of this cross-linked c...

Background: Aerial plant surfaces are covered by a lipophilic cuticular membrane (CM) that restricts the transport of water and small solutes. Non-aerial tissues do not exhibit such a barrier. Recent data have shown that large relative to CM hydrophilic agrochemicals were able to pass at high rates through the non-aerial coleoptile. Results: A m...

Alkyl ether sulfates having 1 to 9 carbon atoms in the alkyl chain and 1 to 20 alkyleneoxy units in the ether moiety are suitable for use as low-foam additives for enhancing the activity of water-soluble or partially water-soluble agrochemicals. They can be used to produce low-foam preparations for crop protection.

Most formulants and adjuvants are low molecular weight solutes and can principally be sorbed in the surface lipids and deeper layers of the cuticle. This can have huge impact on the sorption potential of actives and their mobility in the rate limiting barrier of the cuticle. Factors like volatility, photostability, plant compatibility, selectivity,...

Weeds affect everyone in the world by reducing crop yield and crop quality, delaying or interfering with harvesting, interfering with animal feeding (including poisoning), reducing animal health, preventing water flow, as plant parasites, etc. Weeds are common everywhere and cause many $ billions worth of crop losses annually, with the global cost...

Figure 54.1 (A) Abutilon theophrasti, Champaign, IL, July 2009; (B) flower enlarged. Figure 54.2 Fruits (capsules) of A. theophrasti in a German sugar beet field. Figure 54.3 Germinating seed of A. theophrasti. Figure 54.4 Testa of A. theophrasti seed. Figure 54.5 Seedling of A. theophrasti. Figure 54.6 Transverse section through a shoot of A. theo...

Figure 38.1 Various types of fruits: (A) Rumex obtusifolius; (B) Capsella bursa-pastoris; (C) Linaria vulgaris; (D) Solanum nigrum. Figure 38.2 Longitudinally sliced pod of Senna obtusifolia (L.) H.S. Irwin & Barneby (Syn.: Cassia obtusifolia L.) with developing seeds – one carpel! Figure 38.3 Longitudinally opened silique of Raphanus raphanistrum...

Foliar application is done under a wide range of environmental situations. While regulation often sets a limit for the maximum wind velocity and other climate parameters allowed for a given spray application technique, the variation for temperature and humidity is still high. For example, the air temperature on a weed surface in contact with a sulf...

Leaf wettability considerably defines the degree of retention of water and agrochemical sprays on crop and non-target plant surfaces. Plant surface structure varies with development therefore the goal was to characterise the wettability of soybean leaf surfaces as a function of growth stage (GS). Adaxial surfaces of leaves developed at GS 16 (BBCH)...

Cereal leaf surfaces are densely covered with crystalline epicuticular waxes (EW). Under conditions of extreme radiation, heat and/or drought, several cereals develop a pronounced, often bluish wax bloom. Ignoring the chemistry of EW, they can affect the bioavailability of agrochemicals by making the surface in fact non-wettable for water, and/or f...

It is shown that water permeabilities and organic solute mobilities in plant cuticles have a lognormal distribution. Seven-hundred and fifty values for rate constants of desorption (∼mobility) of 2,4-D from isolated Citrus aurantium L. cuticles from a population of leaves were pooled and analysed. A histogram of the rate constants of individual cut...

The effects of adjuvants on spreading of small droplets after spray application and of larger drops with volumes in the microliter range was studied. The characterization of spreading as affected by adjuvants is done often with lab tests on artificial surfaces. In these tests much larger drops in the microliter range are used and plant factors such...

Rheological properties and spray features of Infinito® and their impact for enhanced user properties and directed release of fluo- picolide Infinito® is a new flowable formulation containing 62.5 g/L of fluopicolide and 625 g/L of propamocarb hydrochloride. It is a high performance product for the control of oomycete phytopathogens, es- pecially in...

Mobilities of lipophilic organic solutes in cuticular membranes (CM) isolated from mature leaves of Citrus aurantium L., Citrus grandis L., Hedera helix L., IIex aquifolium L., Ilex paraguariensis St.-Hil., Mains domestica Borkh., Prunus armeniaca L., Primus laurocerasus L., Pyrus communis L., Pyrus pyrifolia (Burm. f.) Nakai, Stephanotis florihund...

The effects of EDTA (ethylene diamine tetraacetic acid), Kresoxim-methyl, Wettable Sulphur 80 WP and the surfactants Triton X-100, Triton X-114, Dehydol TA 5 and Dehydol TA 29 on pollen tube growth of Malus domestica, Borkh. cvs ‘Golden Delicious’ and ‘Mondial Gala’ were determined by image analysis. The ED50 - and ED90 - values (effective doses gi...

The effect of waxes on the mobilities of organic solutes in isolated leaf cuticular membranes (CM) of six species was investigated using compounds with molar volumes ranging from 99 cm3 mol–1 (salicylic acid) to 349 cm3 mol–1 (cholesterol). When log(solute mobility) was plotted versus molar volumes straight lines were obtained for all plant species...

The hypothesis was tested that the spraying of poorly wettable plants with appropriate adjuvant containing sprays that act as wetting agents causes a long lasting increase of the surface wettability. In the experiments pot grown barley plants were sprayed, using air injection nozzles at 300 L/ha, with a binary (1+1 w/w) blend of two nonionic ethoxy...

The potential of selected surfactants and other adjuvants to increase cuticular penetration of foliar applied active ingredients was investigated under defined environmental conditions (RH, T). The herbicide cyanazine and the weak acid NAA were selected as model compounds. The time course of cyanazine penetration through apple leaf cuticles in the...

When NAA is used for fruit thinning, results can be unpredictable. Problemswith foliar penetration of NAA can contribute to this variability. Usingisolated pear leaf cuticles we have investigated effects of humidity,temperature, hard water and selected adjvants on rates of cuticularpenetration of NAA. If NAA was dissolved in deionised water about 4...

Using time-lapse video microscopy and image analysis we have studied growth rates of pollen tubes of apple (cv. Golden Delicious) pollen. Large numbers of pollen (300 to 500 per replicate and 4 replicates) were analysed simultaneously and growth rates of pollen tubes of very large populations were measured quantitatively, accurately and much faster...

Rates of foliar uptake are often limited by slow cuticular penetration of active ingredients (ai). Rates of cuticular penetration have been modelled based on two processes, namely solute mobility in cuticles (k*) and partitioning of ai or adjuvants between the formulation residue, and cuticular waxes (Kwxfr). The model distinguishes between effects...

Polydisperse ethoxylated fatty alcohol (EFA) surfactants can improve the performance of crop protection agents. At the cuticular level they act as accelerators of penetration by increasing the mobility of active ingredients in the cuticle, the barrier properties of which are mainly caused by cuticular waxes. Polydisperse Genapol C-050 (GP C-050, av...

Effects of poly(ethylene glycol) (PEG 400) and polydisperse fatty alcohol ethoxylates ("Genapols") on methylglucose penetration across cuticles of Pyrus communis were studied under different humidities and temperatures. All surfactants increased methylglucose penetration better than PEG 400. The efficacy was proportional to their own penetration. G...

Solute mobilities in cuticular membranes of six species (Hedera helix, Malus domestica, Populus alba, Pyrus communis, Stephanotis floribunda, Strophantus gratus) were measured using plant hormones, growth regulators and other organic model compounds varying in molar volumes from 99 to 349 mL · mol−1 The dependence of mobilities (k*) on molar volume...

The driving force for foliar penetration is the product of the partition coefficient (K) between the cuticle and the formulation residue, and the concentration of the active ingredient in the spray residue. Ethylene glycols and polyethylene glycols (PEGs) are often contained in commercial formulations, because they are good solvents and not toxic....

Plants have protective pigments absorbing destructive shortwave radiation. These pigments have been found in the epidermis and mesophyll of leaves. We studied the absorption characteristics of the leaf cuticle, the outermost part of the epidermis that is directly exposed to radiation. Adaxial leaf cuticles of apple, pear, sour cherry, strawberry, c...

Temperature dependence of solute mobilities (k*) in leaf cuticular membranes (CM) from Citrus aurantium and Pyrus communis before (k*(pls)) and after (k*(C8E4)) sorption of C8E4 in CM was measured. Average concentrations of C8E4 in cuticles amounted to 8.1% and temperatures ranged from 15 to 35 °C. Activation energies of diffusion were constant for...

The effects of polydisperse ethoxylated fatty alcohol (EFA) surfactants on the penetration of six organic compounds varying in size (molar volumes, 107–282 cm3 mol-1) and lipophilicity (log Kow 0·8–6·5) were investigated using astomatous isolated cuticular membranes (CM) of Citrus and pear leaves. Mobilities of model compounds in CM were measured b...

After spraying, water evaporates and foliar penetration proceeds from a formulation residue of active ingredients and adjuvants which may contain water depending on relative humidity and hygroscopic compounds present. Rates of uptake depend on solute mobility in and driving force across cuticles, which are proportional to the cuticle/formulation re...

The penetration of radiolabelled octaethylene glycol dodecyl ether (C12E8) across astomatous leaf cuticles from five plant species with special regard to pear (Pyrus communis L.) was studied. Velocity of penetration across pear cuticles was highest during the first 2 h and it increased with concentration. Fifty to 80 % of the applied dose penetrate...

Permeabilities of cuticles determine rates of foliar uptake of pesticides. Permeability is proportional to solute mobility and differential solubility in cuticles and permeability can be increased by certain adjuvants called accelerators. Tetraethylene glycol monooctylether (C8E4) is an accelerator. We have measured solute mobilities in Citrus leaf...

Solute mobilities of 28 compounds in isolated cuticular membranes (CM) from Capsicum annuum L. fruit, Citrus aurantium L. and Pyrus communis L. leaves were studied using unilateral desorption from the outer surface. First-order rate constants of desorption (k*), which are directly proportional to the diffusion coefficient in the waxy outer limiting...

The mobility of chlorfenvinphos in isolated pear (Pyrus communis cv. Bartlett) leaf cuticular membranes (CM) was studied as a function of concentration of chlorfenvinphos sorbed in the cuticle. Mobilities of chlorfenvinphos increased approximately 9-fold when the amount sorbed increased from 1 to 100 μg cm−2 pear leaf cuticle. From the amounts per...

Plant leaf surfaces constitute an important habitat for micro-organisms in many vegetation types. Bacteria, yeasts, fungi and lichens can be found and the bacterial population alone ranges from 104 to 106 cells/cm2 (Libbert and Manteuffel, 1970; Hirano and Upper, 1983). These micro-organisms are essentially immobile on leaves and for those which ar...

Many factors may limit the foliar uptake of organic compounds. A short survey is given of the factors governing the foliar uptake of organic compounds as limited by rates of cuticular penetration. Passive transport across a lipid membrane like the cuticle is the product of permeability and driving force. Both terms can be manipulated selecting appr...

Plant surfaces are exposed to a wide range of temperatures even under a temperate climate. The effect of temperature on the diffusion of three model compounds differing in molar volumes and lipophilicity was studied using radiolabelled 2,4-D, chlorfenvinphos, 1-(3-fluoromethylphenyl)-5phenoxy-1,2,3,4-tetrazole and cuticular membranes isolated from...

A theory of cuticular penetration of crop protection agents (CPAs) is presented, which incorporates properties of cuticles and cuticular waxes as well as properties of active ingredients and adjuvants. Based on this theory, two models are developed which are analytical in the sense that they help to quantify and understand (i) differences in permea...