Content uploaded by Mudasir Ahmad Mir
Author content
All content in this area was uploaded by Mudasir Ahmad Mir on Mar 16, 2019
Content may be subject to copyright.
A preview of the PDF is not available
An Overview of Apple Scab, its Cause and Management Strategies
Abstract
Apple scab is the most important disease of apple (Malus × domestica) throughout the temperate regions of world. This disease results in 70% yield loss and even complete loss is also possible, if it is not managed in orchards properly. The infection begins in spring when ascospores are released and infect young emerging apple leaves. Conidia are then produced from these infections and continue the cycle of secondary infection in leaves and fruits. Different management strategies like cultural, biological, resistance and chemical approach has been adopted for its control. However, development of scab resistant apple cultivars carrying the Vf resistance gene could be a step toward a more ecological-based production system for producing high quality apples with reduced fungicide input.
... In the Jammu and Kashmir state, this disease was reported in 1970s and ever since, it has caused havoc in the apple industry with the extent of fruit loss of up to 60%, estimating an amount in hundreds of crores [4]. V. inequalis, being a heterothallic haploid ascomycete, reproduces both sexually and asexually [3][4][5][6]. The disease takes the severe form in regions in which recurrent rainfall through the spring seasons leads into ascospore emancipation and infection [5]. ...
... V. inequalis, being a heterothallic haploid ascomycete, reproduces both sexually and asexually [3][4][5][6]. The disease takes the severe form in regions in which recurrent rainfall through the spring seasons leads into ascospore emancipation and infection [5]. In spring, the predisposing factors such as temperature and moisture conditions are favorable and ascospores are both released and disseminated by wind to bring about epidemics. ...
... As the disease is polycyclic in nature, multiple fungicide applications are needed to assess this disease [10]. It shall be noted that some limited research studies have managed to contain the disease by spraying only five chemical-based fungicidal compounds at critical growth stages of the crop [4,5]. Systemic fungicide sprays limited to seven in number have previously been able to contain the disease but due to the emergence of fungicide resistance in pathogens, these practices have become obsolete [6]. ...
... In the Jammu and Kashmir state, this disease was reported in 1970s and ever since, it has caused havoc in the apple industry with the extent of fruit loss of up to 60%, estimating an amount in hundreds of crores [4]. V. inequalis, being a heterothallic haploid ascomycete, reproduces both sexually and asexually [3][4][5][6]. The disease takes the severe form in regions in which recurrent rainfall through the spring seasons leads into ascospore emancipation and infection [5]. ...
... V. inequalis, being a heterothallic haploid ascomycete, reproduces both sexually and asexually [3][4][5][6]. The disease takes the severe form in regions in which recurrent rainfall through the spring seasons leads into ascospore emancipation and infection [5]. In spring, the predisposing factors such as temperature and moisture conditions are favorable and ascospores are both released and disseminated by wind to bring about epidemics. ...
... As the disease is polycyclic in nature, multiple fungicide applications are needed to assess this disease [10]. It shall be noted that some limited research studies have managed to contain the disease by spraying only five chemical-based fungicidal compounds at critical growth stages of the crop [4,5]. Systemic fungicide sprays limited to seven in number have previously been able to contain the disease but due to the emergence of fungicide resistance in pathogens, these practices have become obsolete [6]. ...
Citation: Padder, S.A.; Mansoor, S.; Bhat, S.A.; Baba, T.R.; Rather, R.A.; Wani, S.M.; Popescu, S.M.; Sofi, S.; Aziz, M.A.; Hefft, D.I.; et al. Bacterial Endophyte Community Dynamics in Apple (Malus domestica Borkh.) Germplasm and Their Evaluation for Scab Management Strategies. J. Fungi 2021, 7, 923. https://doi.
... In the Jammu and Kashmir state, this disease was reported in 1970s and ever since, it has caused havoc in the apple industry with the extent of fruit loss of up to 60%, estimating an amount in hundreds of crores [4]. V. inequalis, being a heterothallic haploid ascomycete, reproduces both sexually and asexually [3][4][5][6]. The disease takes the severe form in regions in which recurrent rainfall through the spring seasons leads into ascospore emancipation and infection [5]. ...
... V. inequalis, being a heterothallic haploid ascomycete, reproduces both sexually and asexually [3][4][5][6]. The disease takes the severe form in regions in which recurrent rainfall through the spring seasons leads into ascospore emancipation and infection [5]. In spring, the predisposing factors such as temperature and moisture conditions are favorable and ascospores are both released and disseminated by wind to bring about epidemics. ...
... As the disease is polycyclic in nature, multiple fungicide applications are needed to assess this disease [10]. It shall be noted that some limited research studies have managed to contain the disease by spraying only five chemical-based fungicidal compounds at critical growth stages of the crop [4,5]. Systemic fungicide sprays limited to seven in number have previously been able to contain the disease but due to the emergence of fungicide resistance in pathogens, these practices have become obsolete [6]. ...
The large genetic evolution due to the sexual reproduction-mediated gene assortments and propensities has made Venturia inaequalis (causing apple scab) unique with respect to its management strategies. The resistance in apple germplasm against the scab, being controlled for by more than fifteen genes, has limited gene alteration-based investigations. Therefore, a biological approach of bacterial endophyte community dynamics was envisioned across the apple germplasm in context to the fungistatic behavior against V. inaequalis. A total of 155 colonies of bacterial endophytes were isolated from various plant parts of the apple, comprising 19 varieties, and after screening for antifungal behavior followed by morphological, ARDRA, and sequence analysis, a total of 71 isolates were selected for this study. The alpha diversity indices were seen to fluctuate greatly among the isolation samples in context to microflora with antifungal behavior. As all the isolates were screened for the presence of various metabolites and some relevant genes that directly or indirectly influence the fungistatic behavior of the isolated microflora, a huge variation among the isolated microflora was observed. The outstanding isolates showing highest percentage growth inhibition of V. inaequalis were exploited to raise a bio-formulation, which was tested against the scab prevalence in eight apple varieties under controlled growth conditions. The formulation at all the concentrations caused considerable reductions in both the disease severity and disease incidence in all the tested apple varieties. Red Delicious being most important cultivar of the northwestern Himalayas was further investigated for its biochemical behavior in formulation and the investigation revealed different levels of enzyme production, chlorophyll, and sugars against the non-inoculated control.
... pple trees (Malus domestica Borkh.) are one of the most widely planted fruit trees worldwide (Shafi et al., 2019). This popular fruit tree has thousands of different cultivars. ...
This study was conducted during the growing season of 2021 and 2022 in horticulture station located at Akre city center Duhok Iraqi Kurdistan region, the study was aimed to investigate the effect of growth regulators on seedling growth of apricot and determined the best concentration of Gibberellin, Benzyl adenine and Kinetin to improve vegetative growth of seedling of apricot . so it consisted of three concentration of GA3 (0, 250 and 500 mg.L-1), BA (0,150 and 300 mg.L-1), KIN (0,150 and 300 mg.L-1) on some vegetative growth characteristics of apricot seedlings (Prunus armeniaca L.).The best results include the following. apricot seedlings sprayed with different concentrations of GA3 significantly affected and gave the seedling height, number of leaves, dry weight, single leaf area and total chlorophyll. Also, seedling sprayed with different BA concentration effected significantly and gave the highest seedling diameter, number of leaves, single leaf area, and dry weight. Whereas seedling spray with different KIN concentrations significantly affected on seedling diameter and total chlorophyll. Generally, interaction between GA3 and KIN and interaction between GA3 and BA and the interaction between BA and KIN was effected significantly on most growth parameters. The best result was in the treatment (GA3 500 mg.L-1 + BA 300 mg.L-1 + KIN 150 mg.L-1) which significantly affected on all growth parameters (seedling height, seedling diameter, single leaf area, total chlorophyll, number of leaves and dry weight)
... pple trees (Malus domestica Borkh.) are one of the most widely planted fruit trees worldwide (Shafi et al., 2019). This popular fruit tree has thousands of different cultivars. ...
This experiment was conducted during 2021-2022 in the Duhok University nursery, Iraqi Kurdistan region, to study the effects of three different Apple cultivars (Super red, Scarlet and Royal caka), three different budding dates (28th August,18th September and 8th October of 2021) and three levels of balanced fertilizer N20%, P20% and K20 %; (0 g, 2g and 4g. l-1) on the budding successful percentage and some vegetative growth characteristics of apple transplants. The results indicated that the Royal caka cultivar had significant effect on the budding success percentage, transplant(scion) height, transplant (scion) diameter, lateral branches number, leaves number and single leaf area. On the other hand, the date (8th Oct.) give the highest significant effect on budding success, transplant(scion) height, leaves number, and single leaf area. However, the 3rd fertilization concentration (4 g. l-1) had a significant effect on the budding success percentage, transplant (scion) height and transplant (scion) diameter, lateral branches number, leaves number and single leaf area. The triple interaction among (Royal caka cultivar + 3rd budding date (8th Oct.) + 3rd fertilization concentration (4 g. l-1) significantly affected on budding successful percentage and most vegetative growth characteristics
... Apple (Malus × domestica Borkh.) belongs to the Rosaceae family and is one of the most important remunerative pome fruits grown across temperate regions of the world [1]. In India, the apple is cultivated mostly in northwestern Himalayan states viz., Jammu & Kashmir (J&K), Himachal Pradesh (HP) and Uttarakhand, and forms the backbone of their economy [2]. ...
Many viruses have been found associated with apple mosaic disease in different parts of the world. In order to reveal and characterize the viruses and viroids in symptomatic apple plants, next-generation sequencing (RNA seq.) of rRNA-depleted total RNA using Illumina Hiseq2500 was applied to two cultivars, Oregon Spur and Golden Delicious, with symptoms of mosaic and necrosis and one cultivar, Red Fuji, which was asymptomatic. The RNA sequencing detected five viruses, viz., apple necrotic mosaic virus (ApNMV), apple mosaic virus (ApMV), apple stem grooving virus (ASGV) and apple stem pitting virus (ASPV), apple chlorotic leaf spot virus (ACLSV), and one viroid i.e., apple hammerhead viroid (AHVd). RT-PCR amplification and sequencing also confirmed the presence of all these five viruses and viroids detected in HTS of total RNA. The complete genomes of five viruses and AHVd were reconstructed. The phylogenetic analysis of these viruses and AHVd revealed genetic diversity by forming subclusters with isolates from other countries. Recombination events were observed in all five viruses while single-nucleotide variants were detected only in ApMV and ApNMV. The absence of ApMV and ApNMV in asymptomatic samples from the same cultivars in an RT-PCR assay indicated that these two viruses are associated with mosaic disease of apples in India. This is the first viral genome analysis of symptomatic and asymptomatic apple plants and the first report of genome characterization of viruses associated with apple mosaic disease from India. High-throughput RNA sequencing is a powerful tool to characterize the genome of viruses and viroids in plants previously undetected by conventional methods. This would also help in the indexing and certification of large-scale germplasm
... 1 Losses in apple production are caused by many pathogens including the fungus Venturia inaequalis causing apple scab disease. 2 It has been estimated that the yield loss caused by Venturia inaequalis may even exceed 70%. 3,4 Protection of apple trees against apple scab disease is provided mainly by chemical treatments performed in accordance to the indications of prognostic models, for example, RIMpro or A-scab. On the basis of analysis of atmospheric data and simulations, these models enable tracking the maturation process of Venturia inaequalis spores. ...
Development of new plant protection strategies has become an urgent matter in modern agriculture, in view of the evidently proved negative effect of currently used active ingredients of pesticides. In recent years, much effort has been made to eliminate the use of pesticides established to be toxic to pollinators. In this study, we present a group of new bifunctional ionic liquids based on dodine (N-dodecylguanidine) cation whose physical and biological properties have been modified relative to those of the commercially available N-dodecylguanidine acetate. First of all the decreased level of residue of active substances in plant tissues reduces their availability to pollinators, which increases the safety of their use. Moreover, lower environmental impact in combination with high antifungal activity and an additional biological function, that is the systemic acquired resistance induction, are in line with the goals of sustainable agriculture.
This article is protected by copyright. All rights reserved.
... It ranks number one disease in terms of yield loss, which poses potential threat to apple industry [4]. This disease imposes a severe threat in commercial apple growing regions, due to premature fruit drop and unmarketable diseased fruits and results in losses up to 70% [5] or even complete crop loss is possible if prophylactic steps are not taken in the orchard for its management [6]. Scab disease is caused by Venturia inaequalis Cooke (Wint.) ...
Apple scab caused by Venturia inaequalis Cooke (Wint.) is one the important diseases of trade and industrial significance in apple. In present study variability studies in pathogen isolates were studied, which is one of the most important factors for devising management studies of scab disease in apple. Genetic diversity of 30 Venturia inaequalis isolates from 12 districts of two geographical distinct regions of Jammu and Kashmir was calculated based on the allele frequencies of 28 SSR markers and the internal transcribed spacer (ITS) region of the ribosomal DNA. The ITS based characterized sequences were submitted to NCBI GenBank and accession numbers were sanctioned. Dendrogram showed that all the accessions formed 2 main clusters with various degree of sub clustering within the clusters. Analysis based on SSR study reveals that the heterozygosity ranged from 0.0 and 0.5, with an average value of 0.39. The expected heterozygosis or gene diversity (He) ranged from 0.0 to 0.50 with an average of 0.40. The Fst value ranges from 0 to 0.6 with an average of 0.194. Diversity within each population (HS) values ranging from 0.26 to 0.33. Average differentiation among populations (GST) was 0.11 and populations were isolated by significant distance (r 2 = 0.50, P < 0.01). From the AMOVA analysis, 25% of variation was observed among population, 9% among individuals and 66% within individuals observed in the population. Structure analysis grouped isolates into two populations. Principle coordinate analysis explained variation of 36.6% in population 1, 14.30% in population 2 and 13.10% in population 3(Admixture) with 64.07% as overall cumulative percentage of variation. This indicates that extensive short-distance gene flow occurs in Kashmir region that dispersal over longer distances also appears to occur frequently enough to prevent differentiation due to genetic drift. Also it is evident that Jammu and Kashmir most likely has V. inaequalis subpopulations linked to diverse climatic conditions of the Jammu region compared to the mountainous inland Kashmir region. The results of present study would help to understand the genetic diversity of V. inaequalis from Jammu and Kashmir that would lead in the development of more effective management strategies and development of new resistant cultivars through marker-assisted selection.
Sustainable horticultural practices address the global issues of food security , pest and disease management, soil health, water pollution, depletion of biodiversity etc. with environment-friendly approaches. Increasingly, the adoption of such strategies is benefitting agricultural production including in orchards. Even though several strategies such as Integrated Pest Management (IPM), disease and weed mitigation have been in use for the elimination of pests, diseases and weeds in apple orchards, they are still not the most favoured methods of control. There are various economic and acceptance concerns regarding their use, particularly in developing nations like India. A more viable system for apple orchards management, thus, should be adopted. Here, we review various different approaches, including sustainable biocontrol methods, employed in the apple orchards. Use of genetically engineered pest-resistant varieties, bio-pesticides, plant-derived insecticides , sanitation methods and adoption of technology for evaluating the accuracy of these methods as well as monitoring of orchards are some of the management strategies included in the study. Further, conventional biocontrol practices, such as engaging natural enemies of harmful pests, use of companion plants or setting up of hedges and windbreaks for enhancing beneficial pest populations, application of compost for improving soil health and interplanting are also employed. Sustainable IPM methodol-ogies can be integrated with biocontrol strategies leading to the development of environmentally feasible management of apple orchards. Such systems will not only reduce dependence on chemical control methods but will also minimize ecotoxicity. Drawing parallels between the biocontrol methods adopted in sustainable agri-production in other fruit orchards suggest other strategies that can be employed for sustainable apple production
Apple scab is one of the most widespread diseases of apple trees causing huge economic losses both quantitatively and qualitatively. The increased expenses associated with labor and fungicides justify the investigation of an alternative, effective, least expensive resistance approach to deal with this disease. In present study we evaluated different cultivars and selections against apple scab disease, using phenotypic and molecular approaches. Phenotypic screening using leaf detach method showed that, in certain cultivars and selections fungus did not proliferate macroscopically and the leaves remained alive, green and also showed hypersensitive response, which gives indication of resistance against apple scab. To validate the results of phenotypic screening, all twenty four cultivars were evaluated for the presence of Vf gene conferring resistance against apple scab disease using gene specific primers. Certain gene specific markers amplified only one fragment in resistant cultivars and hence confirmed the presence of Vf gene in these cultivars. Some amplified fragments in both susceptible and resistant lines, hence couldn't distinguish between resistant and susceptible ones. Present study confirmed the resistance both by phenotypic and molecular screening, hence can play an important role in designing future molecular breeding programme in apple for introgression of scab resistant genes.
Overwintering of conidia of Venturia inaequalis associated with shoots and buds was determined, and the contribution to early spring epidemics of apple scab was evaluated during three consecutive seasons (1999 to 2001) in the Netherlands. Examinations of shoot samples collected before bud break showed that the percentage of shoots with superficial black fungal mycelia or conidia was above 65%, and the mean number of conidia on a 1-cm piece of shoot length ranged from 581 to 1,033. However, germination tests showed that the viability of conidia on shoots was less than 1.5%. No macroscopic scab lesions were detected on the scales of dormant buds. However, microscopic examinations of individual bud tissues demonstrated that the number of conidia was >3,000 per 100 buds in each year. The mean viability of conidia associated with buds ranged from 0.7 to 1.9% and from 3.7 to 10.5% for the outer and inner bud tissues, respectively. Results of field assessments at tight-cluster phenological stage showed that the percentage of infection caused by the viable overwintered conidia ranged from 0.3 to 3.8% in the various treatments. Our results indicated that conidia were unlikely to overwinter on the surface of shoots or outer bud tissues, where they were exposed to fluctuating environmental conditions, and, consequently, were unlikely to play a role in initiating an early epidemic of apple scab in the spring. However, our results indicated a risk from overwintered conidia in the inner bud tissues arising from a high level of scab the previous autumn. Therefore, orchards with high levels of apple scab, where ascosporic inoculum is much reduced, e.g., by sanitation, should be protected in early spring by means of fungicide treatment at green tip.
An inorganic (sulfur) and a conventional organic fungicide spray program were evaluated on an apple scab-resistant (Liberty) and a scab-susceptible (McIntosh) cultivar for control of scab and for cost effectiveness. Trees of both cultivars were either nontreated, treated with inorganic fungicides only, or treated with a conventional fungicide program. McIntosh trees received full-season fungicide applications and Liberty trees received only the summer cover sprays (after petal fall) for control of summer diseases, In 1991, the number of fungicide applications ranged from 0 for nontreated Liberty to 12 for the full-schedule inorganic program on McIntosh, with both treatments providing excellent scab control. All nontreated McIntosh fruit were unmarketable due to scab infection, Due to a dry growing season and lack of summer disease development, nontreated Liberty fruit was of high quality. In 1992, the number of fungicide applications ranged from 0 for nontreated Liberty to 14 for the full-schedule inorganic treatment on McIntosh, with both treatments providing good to excellent disease control. Results were very similar in 1993. Scab incidence was low for all treatments except the nonsprayed McIntosh over all years. Over 3 years of testing, the conventional fungicide program resulted in an average of 9 and 5 applications per year for McIntosh and Liberty, respectively, compared to 12.6 and 7 applications, respectively for the inorganic fungicide program. The large reduction in the number of sprays for both programs was due to the elimination of all pre-petal-fall applications on Liberty; post-petal-fall applications are needed to control summer diseases such as flyspeck and sooty blotch. An economic analysis for total cost of fungicide applications for each spray program and cultivar was conducted for hypothetical 4.0-, 8.1- and 16.2-ha farms, Regardless of farm size, the cost of fungicides per ha varied among treatments and cultivars. The inorganic and conventional spray program for McIntosh had similar total costs, On Liberty, the inorganic and conventional programs had 73 anti 57%, less total cost, respectively, than on McIntosh. Fungicides for the conventional program on Liberty were 1.45 times more costly par ha than fungicides in the inorganic program, but the inorganic program required more applications, resulting in a small difference in total treatment cost per ha.
Unlabelled:
The fungus Venturia inaequalis infects members of the Maloideae, and causes the disease apple scab, the most important disease of apple worldwide. The early elucidation of the gene-for-gene relationship between V. inaequalis and its host Malus has intrigued plant pathologists ever since, with the identification of 17 resistance (R)-avirulence (Avr) gene pairings. The Avr gene products are presumably a subset of the total effector arsenal of V. inaequalis (predominantly proteins secreted in planta assumed to facilitate infection). The supposition that effectors from V. inaequalis act as suppressors of plant defence is supported by the ability of the pathogen to penetrate the cuticle and differentiate into large pseudoparenchymatous structures, termed stromata, in the subcuticular space, without the initiation of an effective plant defence response. If effectors can be identified that are essential for pathogenicity, the corresponding R genes will be durable and would add significant value to breeding programmes. An R gene cluster in Malus has been cloned, but no V. inaequalis effectors have been characterized at the molecular level. However, the identification of effectors is likely to be facilitated by the resolution of the whole genome sequence of V. inaequalis.
Taxonomy:
Teleomorph: Venturia inaequalis Cooke (Wint.); Kingdom Fungi; Phylum Ascomycota; Subphylum Euascomycota; Class Dothideomycetes; Family Venturiaceae; genus Venturia; species inaequalis. Anamorph: Fusicladium pomi (Fr.) Lind or Spilocaea pomi (Fr.). LIFE CYCLE: V. inaequalis is a hemibiotroph and overwinters as pseudothecia (sexual fruiting bodies) following a phase of saprobic growth in fallen leaf tissues. The primary inoculum consists of ascospores, which germinate and penetrate the cuticle. Stromata are formed above the epidermal cells but do not penetrate them. Cell wall-degrading enzymes are only produced late in the infection cycle, raising the as yet unanswered question as to how V. inaequalis gains nutrients from the host. Conidia (secondary inoculum) arise from the upper surface of the stromata, and are produced throughout the growing season, initiating multiple rounds of infection. VENTURIA INAEQUALIS AS A MODEL PATHOGEN OF A WOODY HOST: V. inaequalis can be cultured and is amenable to crossing in vitro, enabling map-based cloning strategies. It can be transformed readily, and functional analyses can be conducted by gene silencing. Expressed sequence tag collections are available to aid in gene identification. These will be complemented by the whole genome sequence, which, in turn, will contribute to the comparative analysis of different races of V. inaequalis and plant pathogens within the Dothideomycetes.
Potential and Prospects of J&K Economy
- T A Bhat
- T A Lone
Bhat TA and Lone TA. "Potential and Prospects of J&K Economy". Educreation Publishing (2017).
Pest Problems in Fruit Crops
- D P Abrol
Abrol DP. "Pest Problems in Fruit Crops". Pollination Biology, Volume 1: Springer (2015): 59-90.
Diseases of temperate zone tree fruit and nut crops
- J M Ogawa
- H English
Ogawa JM and English H. "Diseases of temperate zone tree fruit and nut crops". UCANR Publications (1991).
Apple scab: biology, epidemiology, and management
- W E Machardy
MacHardy WE. "Apple scab: biology, epidemiology, and management". APS press St. Paul (1996).
Development of Biological Control Strategies for Integrated Management of Pre-and Postharvest Diseases of Apple in Pennsylvania
- A M Poleatewich
Poleatewich AM. "Development of Biological Control Strategies for Integrated Management of Pre-and Postharvest Diseases of Apple
in Pennsylvania" (2010).