Disease In Apple Orchards Research Articles

Deciphering the mechanisms involved in reduced sensitivity to azoles and fengycin lipopeptide in Venturia inaequalis

Apple scab, caused by the hemibiotrophic fungus Venturia inaequalis, is currently the most common and damaging disease in apple orchards. Two strains of V. inaequalis (S755 and Rs552) with different sensitivities to azole fungicides and the bacterial metabolite fengycin were compared to determine the mechanisms responsible for these differences. Antifungal activity tests showed that Rs552 had reduced sensitivity to tebuconazole and tetraconazole, as well as to fengycin alone or in a binary mixture with other lipopeptides (iturin A, pumilacidin, lichenysin). S755 was highly sensitive to fengycin, whose activity was close to that of tebuconazole. Unlike fengycin, lipopeptides from the iturin family (mycosubtilin, iturin A) had similar activity on both strains, while those from the surfactin family (lichenysin, pumilacidin) were not active, except in binary mixtures with fengycin. The activity of lipopeptides varies according to their family and structure. Analyses to determine the difference in sensitivity to azoles (which target the CYP51 enzyme involved in the ergosterol biosynthesis pathway) showed that the reduced sensitivity in Rs552 is linked to (i) a constitutive increased expression of the Cyp51A gene caused by insertions in the upstream region and (ii) greater efflux by membrane pumps with the involvement of ABC transporters. Microscopic observations revealed that fengycin, known to interact with plasma membranes, induced morphological and cytological changes in cells from both strains. Sterol and phospholipid analyses showed a higher level of ergosta-7,22-dien-3-ol and a lower level of PI(C16:0/C18:1) in Rs552 compared with S755. These differences could therefore influence the composition of the plasma membrane and explain the differential sensitivity of the strains to fengycin. However, the similar antifungal activities of mycosubtilin and iturin A in the two strains indirectly indicate that sterols are probably not involved in the fengycin resistance mechanism. This leads to the conclusion that different mechanisms are responsible for the difference in susceptibility to azoles or fengycin in the strains studied.

Monitoring of Carbendazim residues in post-harvest treated Red Delicious apples

This research paper aims to provide a comprehensive analysis of the presence and levels of Carbendazim residues in post-harvest treated Red Delicious apples in two condition i.e. ambient stored condition and cold stored condition. Carbendazim, a benzimidazole fungicide, has gained prominence as an effective means of controlling fungal diseases in apple orchards, including the commonly encountered apple scab and powdery mildew. The residue levels of Carbendazim in post-harvest treated Red Delicious apples, however, raise concerns about consumer safety and environmental impact. The investigation encompasses residue analysis methodologies, factors influencing residue levels, and potential mitigation strategies to ensure food safety and sustainability. The study showed that Carbendazim residue persistence was more in cold stored apple compared to ambient stored apple and to reduce its concentration to less than 5ppm it took 60 days, if pesticide applied ate recommended dose. It indicates, that the apple can be produced residue free and safe for consumption if judicious use of pesticides with respect to concentration and time is followed. Pesticides applied properly and scientifically avoiding drift to environment can reduce the impact on human health.

Monitoring the distribution and development of apple scab (Venturia inaequalis) and powdery mildew (Podosphaera leucotricha) disease in the southern and southeast regions of Kazakhstan

Apple (Malus domestica) is a very important fruit tree that is widely cultivated in different climatic regions of the world. Scab (Venturia inaequalis (Cooke) G.) and powdery mildew (Podosphaera leucotricha) are common fungal diseases in apple orchards. The harmful impact of these disease results in poor fruit size and quality, premature fruit fall, peeling, less fruit bud development in the next year's fruit buds. When the patho-gen is present under favorable environmental conditions, disease develops highly, and the crop losses of up to70 %. Phytosanitary monitoring for the spread and development of the scab and powdery mildew pathogen was carried out the main fruit tree-growing regions of Kazakhstan, namely, Almaty, Turkestan and Zhambyl regions apple-growing farms in 2022. Research was conducted on apple orchards on the territory of 14 ha in Almaty region, 288 ha in Turkestan region and 40 ha in Zhambyl region. We carried out a phytopathological assessment of fungal disease for folowing commercial varieties Starkgrimson, Zolotoy presvesov, Aydaret, Americanka, Samured, Gala, Fuji and Golden Delicious grown in these regions. According to the results of the study, there were no symptoms of powdery mildew in Almaty and Zhambyl regions. Furthermore, pow-dery mildew distribution was 18.05 % in the Aidaret, while its development was at a lower level of 3.06 % in the apple orchards where Tulkibas district of Turkestan region. Scab pathogen is present in all orchards of the studied regions. The pathogen Venturia inaequalis was spread at an average level with 23 -31 % in Starkgrim-son, Zolotoy presvesov and Aidaret varieties, while its development was at a low level with 1-2.84 % in the Almaty region. The disease distribution is with 30-37 % of orchards where Starcrimson, Golden Delicious and Red Delicious varieties are grown in the Zhambyl region. As well as the development of the disease was 2-4.12 %. In the Turkestan region, in Samured and Starkrimson varieties, scab ditribution was at a low levelwith 3-3.71 %, while the development of the disease was with 0.50-0.81 %. In Idared and Gala varieties, thedisease distribution in the range about 16-17 %, while the development developed at a lower level with 0.13-1.25 %. The Fuji was recognized as resistant variety to scab, for the reason of no disease symptoms.

Management of premature leaf fall (Marssonina coronaria) of apple with new generation fungicides in the North‐Western Himalayan Region of India

AbstractIn the north‐western Himalayan region of India, premature leaf fall (PLF) caused by Marssonina coronaria is a major disease in apple orchards. Field experiments were conducted at a commercial orchard to evaluate the efficacy of new‐generation fungicides on PLF management during 2018 and 2019. Three contact fungicides (chlorothalonil, propineb and mancozeb), one systemic fungicide (difenoconazole) and four combination products (metiram +pyraclostrobin, fluxapyroxad +pyraclostrobin, tebuconazole +trifloxystrobin and fluopyram +tebuconazole) were evaluated against an untreated control (UTC) by applying them at three times at 15‐day intervals to trees of the susceptible apple cultivar ‘Royal Delicious’. Out of all tested treatments, tebuconazole +trifloxystrobin achieved the lowest area under disease progress curve (AUDPC) and the greatest yield increase. Similarly fluxapyroxad +pyraclostrobin and fluopyram +tebuconazole also significantly reduced AUDPC and enhanced yield relative to the UTC. Taking into account the cost of the tested products, tebuconazole +trifloxystrobin offered the best benefit‐cost ratio in both years, followed by fluxapyroxad +pyraclostrobin and fluopyram +tebuconazole. Based on these findings, the combination products tebuconazole +trifloxystrobin, fluxapyroxad +pyraclostrobin and fluopyram +tebuconazole can all be recommended to the farmers of the north‐western Himalayan region for PLF management.

Classification of Apple Disease Based on Non-Linear Deep Features

Diseases in apple orchards (rot, scab, and blotch) worldwide cause a substantial loss in the agricultural industry. Traditional hand picking methods are subjective to human efforts. Conventional machine learning methods for apple disease classification depend on hand-crafted features that are not robust and are complex. Advanced artificial methods such as Convolutional Neural Networks (CNN’s) have become a promising way for achieving higher accuracy although they need a high volume of samples. This work investigates different Deep CNN (DCNN) applications to apple disease classification using deep generative images to obtain higher accuracy. In order to achieve this, our work progressively modifies a baseline model by using an end-to-end trained DCNN model that has fewer parameters, better recognition accuracy than existing models (i.e., ResNet, SqeezeNet, and MiniVGGNet). We have performed a comparative study with state-of-the-art CNN as well as conventional methods proposed in the literature, and comparative results confirm the superiority of our proposed model.

Magnesium and nitrogen drive soil bacterial community structure under long-term apple orchard cultivation systems

Apple replant disease (ARD) is a common and destructive disease in apple orchards with long cultivation histories. In the present study, soils from three apple orchards under cultivation for two years (G2), thirty years (G30), and forty years (G40) were used to investigate the key nutritional factors influencing soil bacterial community structure. Changes in nutrient concentrations in the orchard soil entailed reductions in concentrations of medium trace nutrients (magnesium [Mg], manganese, and nickel) and the increase in concentrations of macronutrients (total nitrogen [TN], total phosphorus, total potassium, available phosphorus, and available potassium) and soil organic carbon. As cultivation time was prolonged, bacterial community composition shifted from enrichment with oligotrophic Acidobacteria and plant growth-facilitated Streptomyces to increased abundance of copiotrophic taxa, Bacteroidetes and Firmicutes, and plant-growth-impairing Gemmatimonas, based on 16S rDNA (V4) amplicon sequencing data. In addition, the relative abundances of bacteria associated with fermentation function and the decomposition of some unique compound classes increased, while the relative abundance of bacteria associated with the nitrification function decreased. Among all the nutritional elements tested using distance-based multivariate linear model analysis, Mg and TN influenced community structure the most. The results provide novel insights into the associations between soil nutrients and shifts in microbial community structure under long-term apple orchard soil ecosystems.

The Methods Of Intellectual Struggle Against Pest And Disease In Apple Orchards

The article reports about the measures of intellectual struggle for the use of modern information technologies against pests and diseases in apple orchards, the use of mathematical models and the use of computer software to prevent the prediction of harmful organisms.

Performance evaluation of locally available composts to reduce replant disease in apple orchards of central Europe

AbstractA study on locally available composts in Austria, Germany, Italy and Switzerland was conducted to investigate the potential of these non-chemical based tools to increase soil health in orchards afflicted by apple replant disease (ARD). A total of 26 different composts (six to seven per country) were chosen for the study. Composts were divided into ten types according to the waste materials used as substrates in the composting process. Growth reduction is the main symptom associated with replant disease; therefore compost performance was evaluated based on the growth responses of apple rootstock plantlets in compost-amended soils in pots. These greenhouse trials were performed in one research station per country, located in an intensive apple-growing area, and soil was taken from an apple orchard affected by replanting disease. Plant growth response was measured as shoot elongation at the end of each greenhouse trial, and results showed increases in growth compared with the respective controls of 2–26% in 20 out of 26 composts evaluated. The heterogeneous nature of the composts most likely attributed to the finding that similar compost types originating from the different countries had varying effects on plant growth. Overall, no significant changes in chemical and biological properties were observed in amended soils as compared with non-amended controls. The high soil resilience was in part expected given the good organic matter content in the original soils (>2%). The bacterial communities of the composts were investigated using the COMPOCHIP microarray, and analyses showed that differences in plant growth response were mainly attributed to the microbial changes introduced into the soil through composts rather than to changes in soil chemical and biological parameters. However, the bacterial communities of composts appeared to be more influenced by geographical origin than by compost type. The results have shown that soil amendment with composts generated from locally produced wastes have the potential to reduce the effects of ARD, although the effects appear to be both compost and soil specific.

Integrated approach for control of pests and diseases in apple orchards in the region of Central-South Bulgaria

Integrated approach for control of pests and diseases in apple orchards in the region of Central-South Bulgaria

Cut-off shoots method for estimation of partial resistance in apple cultivars to fruit tree canker caused by Neonectria ditissima

Fruit tree canker, caused by the fungus Neonectria ditissima, is an economically devastating disease in apple orchards, especially in north-western Europe. Complete resistance has not yet been reported in apple, but variation in levels of partial resistance has been described and could be valuable in plant breeding programmes. A screening method based on spore inoculation of manually inflicted leaf scars on cut shoots was evaluated for reliability and repeatability in discrimination of 11 apple cultivars during two years – 2012 and 2013 – in two different facilities – biotron and standard greenhouse – and different time periods (February–May). The resulting cankers were counted (infection percentage), first appearance noted (incubation period) and lesion size measured at regular intervals during a period of 25–29 days for comparison of resistance levels. Results of two-way analysis of variance and correlation analyses showed that the area under the disease progress curve yielded the most robust data. This parameter was then applied for screening 30 apple cultivars using the same cut-shoot method. ‘Elise’ showed very high susceptibility, while the ornamental ‘Prairifire’ showed the highest level of partial resistance. Results suggested that cut shoots can be used to assess levels of resistance among cultivars, but great care must be taken to provide stable experimental conditions.

Leaf degradation characteristics of scab resistant and susceptible apple cultivars

In spite, that Venturia inaequalis (Cke.) Wint. is one of the most serious fungal disease in apple orchards and it has been studied from numerous points of view, few studies examined the anatomical differences between scab resistant (Vf cultivars) and susceptible apple cultivars. We have investigated the possible anatomical background of the resistance or susceptibility against apple scab in gradually decaying fallen apple leaves. Specific differences were observed in the process of leaf degradation and in the structure of leaf tissues of each cultivar. The epidermis and the cuticle have continually become thinner during leaf degradation in the leaves of two resistant cultivars, while great deformations were observed in the leaf tissues of the susceptible cultivars caused by the hyphae in the mesophyllum and subcuticular stromas. When comparing the non-infected parts of susceptible leaves with those of the resistant cultivars, we documented earlier disintegration of the parenchyma and declined cohesion be...

Planting in the ‘inter-row’ to overcome replant disease in apple orchards: a study on the effectiveness of the practice based on microbial indicators

Aims A study on the effectiveness of replanting in “inter-row” to minimize replant disease in apple orchards was performed focusing on the plant-microorganism relationship.

Effects of pesticides on the functional response of predatory thrips,Scolothrips takahashiitoTetranychus viennensis

Abstract: It is of importance to integrate the biological control of hawthorn spider mite,Tetranychus viennensis, by predatory thrips in commercial orchards in north China. In this study, a leaf disc bioassay was employed to investigate the effects of two insecticides, i.e. abamectin and fenpropathrin, and two fungicides, i.e. mancozeb and carbendazim, on the functional response of an acarophagous thrips,Scolothrips takahashiiPriesner, to eggs of the mite at the conditions of 25 ± 1°C, 60 ± 10% relative humidity, and a 16 : 8 h (L : D) photoperiod. Results indicated that the type of functional response in predatory thrips differed depending on the types and doses of the pesticides exposed. Holling‐II type responses were exhibited by all predatory thrips but females that were exposed to labelled dose of abamectin and half‐labelled dose of fenpropathrin exhibited the Holling‐III type responses. Parameters of random predator equation for both exposed and unexposed predators were estimated and compared with an equation with indicator variables. Both doses of both fungicide treatments did not have any impact on the attack rates of the thrips. Handling time (Th) estimates for males exposed to both doses of both fungicides were similar to that of the control, but there seemed to be a trend towards prolonged handling times for females in these exposures with a significantly prolonged Thfound in labelled dose of mancozeb. Exposures of both doses of fenpropathrin and labelled dose of abamectin produced significantly lower attack rates and significantly prolonged handling times in both males and females, whereas an exposure of half‐labelled dose of abamectin had no obvious influence on the attack rates of the predator, but the handling time in females prolonged significantly. The theoretical maximum number of prey attacked by the thrips were 59.81 eggs per day per female and 23.21 eggs per day per male in the control, but it reduced by 57.03–71.41% and 6.03–36.75% for females and males in the insecticide exposures and 23.91–44.26% and −5.13–11.55% in the fungicide exposures, respectively. The finding implies that the natural control effects ofS. takahashiiwould be weakened by the application of the pesticides such as fenpropathrin, abamectin and mancozeb, which are often used to control insect pests and fungal diseases in apple orchards.

Sensitivity of Red Delicious Apple Fruit at Various Phenologic Stages to Infection by Alternaria alternata and Moldy-core Control

The fungus Alternaria alternata, is considered to be the predominant fungus involved in moldy-core of Red Delicious strains of apple. In this paper, we report on the sensitivity of various phenologic stages to infection by A. alternata, and on the efficacy of various fungicides in controlling moldy-core disease in apple orchards. Artificial inoculations conducted in the orchard during 1999 and 2000 seasons revealed that the beginning of bloom (10–30%) and full bloom were the most susceptible developmental stages for infection. Natural infection with A. alternata in fruits was relatively high, reaching 44% and 46% of the fruits on control non-treated trees in 1999 and 2000. Four foliar applications of polyoxin B, difenoconazole and azoxystrobin, starting from the beginning of bloom until fruit set, reduced the number of infected fruits by 54–70%, 61–70% and 50–65%, respectively, compared with non-treated trees. Four or eight foliar applications of each fungicide provided similar levels of control. There were no significant differences between two, four or six foliar applications of difenoconazole, neither between two or four applications of polyoxin B. Adding CaCl2, as a tank mixture with difenoconazole at full rate, did not improve efficacy. Alternaria was recovered from the inner part of the core region of 71–88% of the fruits of the non-treated control, but was recovered less frequently from the outside part of the core region. Fruits of difenoconazole and polyoxin B treated trees were less colonized with A. alternata at both the inner and outside parts of the core region, as compared with controls. Results indicate that a control programme based on spray applications of difenoconazole or polyoxin B, during bloom period, can effectively reduce Alternaria on Red Delicious.

Construction of a 550 kb BAC contig spanning the genomic region containing the apple scab resistance gene Vf.

A positional cloning project was started in apple with the aim of isolating the Vf resistance gene of Malus floribunda 821. Vf confers resistance against apple scab, the most important disease in apple orchards. A chromosome walk starting from two molecular markers (M18-CAPS and AM19-SCAR) flanking Vf was performed, using a bacterial artificial chromosome (BAC) library containing inserts of the cultivar Florina, which is heterozygous for Vf. Thirteen BAC clones spanning the region between the two markers were identified in nine chromosome walking steps. The size of the resulting contig is approximately 550 kb. In order to map the Vf region in more detail, we analyzed over 2000 plants from different populations segregating for Vf with markers produced from BAC end sequences. In this way, we were able to restrict the possible location of the Vf gene to a minimum of five clones spanning an interval of approximately 350 kb.