Scab Development Research Articles

Control of a phytopathogenic infection in an apple orchard in the forest-steppe of Samara Oblast

The study evaluates a protection system by selecting and alternating fungicides having different mechanisms of action to exclude the emergence of resistant populations of apple tree pathogens. The experiments were started at Koshelevsky Posad LLC (Syzransky District, Samara Oblast) in 2022-2023. The orchard was planted in 2013-2014, with trees arranged in a 3.5×1.5 m grid; the 62-396 rootstock was used. The biological effectiveness of fungicide protection against apple scab (Venturia inaequalis (Cooke) Wint.) and fruit rot (Monilia fructigena Pers.) was analyzed using ‘Berkutovskoye,’ ‘Kulikovskoye,’ ‘Kuibyshevskoye,’ ‘Lobo,’ and ‘Northern Sinap’ varieties. The protection system including contact and systemic agents having different mechanisms of action was developed according to the FRAC diagram for assessing the combined risk of fungicide resistance developing in phytopathogens, which takes into account the adaptation rate of organisms (emergence of new resistant types) to changing environmental conditions. An analysis of the correlation between the growth rate of apple-specific phytopathogens and weather conditions shows no significant relationship (0.032-0.245). In these studies, the anthropogenic factor-chemical treatment with fungicides – had a predominant effect on the development of scab and monilia in apple orchards along with weather factors. The yield of marketable apples in the experimental quarter of the orchard differed insignificantly from year to year. In 2023, the yield was lower; however, this fact can be probably attributed to the return of late frosts during apple blossom in Samara Oblast. Noteworthy is that for the ‘Berkutovskoye’ and ‘Lobo’ varieties, unmarketable apples did not exceed 5 and 12 %, respectively, in the studied quarter of the orchard. The protection system using fungicides (GC Shans) helped to optimize the phytosanitary condition of the orchard, thus reducing the amount of fallen fruit and providing a stable harvest of marketable apples.

Technologies of physical and chemical impact on potato planting material

The paper highlights that it is planned to increase the cultivation area of open ground vegetables and potatoes for ensuring the food security. (Research purpose) This study aims to explore methods and technologies for pre-planting treatment of potatoes. (Materials and methods) The research was conducted in the Tula region where Rannee Utro (Early Morning) and Rokko potato varieties were studied under natural infectious conditions. Various fungicides and biological products containing different active ingredients were applied to protect potatoes. Additionally, the study investigated the eff ects oflow-pressure mercury ultraviolet discharge lamps and magnetic field treatments on the biopotential and pH levels of potatoes. (Results and discussion) The study focuses on enhancing potato yields by applying direct magnetic field exposure before planting and investigates the impact of ultraviolet irradiation on tuber growth and productivity. Signifi cant emphasis was placed on the efficacy of chemical and biological agents in preventing potato scab. The findings show that optimal biometric indicators and potato yields were achieved with a magnetic induction of 30 millitesla. Any deviation from this treatment dose results in reduced biometric indicators and yields, which, however, remain hirer than those of the untreated controls. (Conclusions) The application of fungicidal disinfectants effectively curtails the development of common scab, with the highest efficacy achieved using Rovral Aquafl o 500. Post-treatment with ultraviolet radiation at a dose of 120-240 joules per square meter enhances vegetative growth, productivity, and tuber reproduction rates. The most favorable biometric indicators and yields were observed when a magnetic induction treatment dose of 0.23 joule-seconds per kilogram was applied.

Improvement of an ecologically safe system of control of fungal diseases for growing on the basis of organic farming

Goal. To assess the level of effectiveness of the elements of control of fungal diseases in potato agrocenoses for various combinations of biofungicides with biologically active substances and fertilizers, methods of application and the reaction of potatoes of the Myroslav variety to them, for growing on the basis of organic farming.
 Methods. The following methods were used during the research: field — monitoring of the main diseases of potatoes in field experiments, crop accounting, determination of the effectiveness of combinations of biofungicides with plant growth regulators, organic and organo-mineral fertilizers; laboratory — accounting for damage to tubers by diseases, according to generally accepted methods.
 Results. In 2021—2022, the Laboratory of Immunity and Plant Protection of the Institute of Potato Breeding of the National Academy of Sciences conducted research on improving the elements of an environmentally safe system of controlling fungal diseases for cultivation based on organic farming. The research used the Myroslav variety of the institute’s selection, biopreparations with insecticidal, fungicidal and growth-regulating action, and organic and organo-mineral fertilizers. The lowest level of Alternaria development was noted in option 9 (treatment of tubers — organic fertilizer + PPR + plant treatment Bactophyt + PPR + organic and organo-mineral fertilizer), the development of the disease was 25.0%, the spread was 35.0 %, and the technical efficiency of the elements protection was 56.7%. It was established that for effective control of the development of common scab, rhizoctoniosis and fusarium dry rot, it is advisable to use a mixture of substances (PPR + organic fertilizer — treatment of tubers + biofungicide + organic and organo-mineral fertilizer + PPR — plant treatment), which significantly reduced the level of disease development tubers and limited their spread, compared to control and standards. The yield of potatoes in the variants was higher than in the control (22.5 t/ha) and was in the range of 31.1—42.0 t/ha. The level of the preserved harvest, relative to the control, was in the range of 8.6—19.5 t/ ha. The highest level of yield is 42.0 t/ha, noted in option 9 (organic fertilizer + PPR treatment of tubers + three Bactophyt plant treatments + organic and organo-mineral fertilizer + PPR) which, respectively, is 19.5 t/ha higher than the control and by 3.1 t/ha — standard.
 Conclusions. The use of tank mixtures of biofungicides with growth regulators and fertilizers significantly reduces the level of potato disease development and helps to increase the level of its yield. It has been established that the mixture of drugs (PPR + organic fertilizer — treatment of tubers + biofungicide + organic and organo-mineral fertilizer + PPR — plant treatment) is advisable to use to control the development of alternariosis, common scab, rhizoctoniosis and fusarium dry rot, since such a combination is ecologically safe for the environment, at the same time significantly reduces the level of development of fungal diseases and limits their spread, in comparison with control and standards, for growing on the basis of organic farming.

Efficiency of the application of biological systems of the protection of apple trees against powdy dew and scamb in the conditions of the Western Forest-Steppe of Ukraine

Goal. To study the effectiveness of different biological systems of apple tree protection against scab and powdery mildew in the Western Forest-Steppe of Ukraine.
 Methods. Phytosanitary monitoring was carried out visually and with the help of pheromone traps. Accounting of the spread and development of diseases was carried out according to generally accepted methods in the phases of apple tree development: «bud swelling», «green cone», «bud extension», «bud separation», «pink bud», «flowering», «end of flowering», «fruit formation», «fruit growth» and «fruit ripening». The technical effectiveness of fungicides was determined after 7 days. Statistical processing of the research results was carried out according to generally accepted methods.
 Results. The results of monitoring the phytosanitary state of apple plantations established that the most common diseases in 2021—2022 in the conditions of the Western Forest Steppe of Ukraine were scab, which affected 15—29% of leaves and 8—13% of apple fruits, powdery mildew, which affected 15—18% of leaves of apple trees, moniliosis, the prevalence of which was 9—13%, and fruit rot, which affected 13—14% of apple fruits. The research results showed that the use of the biological protection system No. 1 (Fluorescin BT, Bactophyt BT, BioHybervit BT, Trihopsin BT, Fluorescin BT) made it possible to reduce the development of powdery mildew by 59.0%, and to reduce the development of scab on leaves and by 59.1%, 62.2% — scab on apple fruits. The use of biological protection system No. 2 (Bactophyt BT + Trihopsin BT, BioHybervit BT, Fluorescin BT, Trihopsin BT, Fluorescin BT) made it possible to reduce the development of powdery mildew by 43.6%, by 47.7% to reduce the development of leaf scab and by 48.6% — scab on apple fruits. The use of biological protection system No. 3 (Ampelomycin BT + Bactophyt BT, Phytosporin + Fluorescin BT, BioGibervit BT, Biospectr BT, Trihopsin BT + Fluorescin BT) made it possible to reduce the development of powdery mildew by 53.8%, and to reduce the development of scab by 68.2% leaves and 67.6% — scab on apple fruits. Using the studied biological systems to protect apple trees from scab and powdery mildew in the conditions of the Western Forest-Steppe of Ukraine yield indicators of 13.2—13.8 t/ha were obtained. The use of the studied biological protection systems made it possible to obtain from 2946 to 8526 UAH/ha of conditional net income and profitability indicators from 72.7 to 229.4%.
 Conclusions. The results of the research established that all investigated systems of biological protection of apple trees against scab and powdery mildew in the conditions of the Western Forest Steppe of Ukraine made it possible to protect apple plantations at a reliable level and obtain high yields. The technical efficiency of the applied protection systems against powdery mildew was 43.6—59.0%, against scab on apple leaves — 47.7—68.2%, and against scab on apple fruits — 48.6—67.6%. The yield for the application of the investigated biological systems of apple tree protection against scab and powdery mildew was 13.2—13.8 t/ha. Biological protection system No. 1 was the most effective in terms of profitability — 229.4%, and the highest indicator of conditional net income was obtained from the use of biological system No. 3 — UAH 8526/ha.

Formulated hydroxy fatty acids from fruit pomaces reduce apple scab development caused by Venturia inaequalis through a dual mode of action.

The outermost hydrophobic layer of plants, i.e. the cuticle, is mainly composed of cutin, a polyester of hydroxy fatty acids with reported eliciting and/or antimicrobial activities for some of them. By-products of the fruit processing industry (fruit pomaces), often strongly enriched in cuticular material, are therefore a potential source of bioactive compounds for crop protection against pathogen attack. We investigated the utilization of tomato and apple pomaces in the development of a cutin-based biocontrol solution against apple scab, a major apple disease caused by Venturia inaequalis. Several cutin monomer extracts obtained through different strategies of depolymerization and purification were first compared for their ability to induce a targeted set of defense genes in apple seedlings after foliar application. After a step of formulation, some extracts were chosen for further investigation in planta and in vitro. Our results show that formulated cutin monomers could trigger a significant transcriptome reprogramming in apple plants and exhibit an antifungal effect on V. inaequalis. Cutin monomers-treated apple seedlings were significantly protected against infection by the apple scab agent. Altogether, our findings suggest that water-dispersed cutin monomers extracted from pomaces are potential new bio-based solutions for the control of apple scab.

Investigation of the chlorophylls and flavonoids content in apple leaves under conditions of various scab protection systems

As part of the study of the effect of fungicides on the development of apple scab in an orchard in the Solnechnogorsk district of the Moscow region, changes in the optical parameters of apple leaves depending on protection systems and varieties were studied. The effectiveness of the express method using the Dualex chlorophyll meter has been proven. This method has the same effectiveness as the traditional spectrophotometric determination of the chlorophylls a and b, but it is faster and easier. The choice of the method of working with the N-tester is justified. Leaves 5-9 of average age, located in the middle of the shoot, were selected as plant samples. They are considered to be the most optimal for assessing the state of the nitrogen status of plants. It has been experimentally proven that the treatment of plants with fungicides based on captan, dithianon, trifloxystrobin and ciprodinil has the positive effect on increasing the plant nitrogen balance index (NBI). The greatest effect of an increase in the NBI index was observed on the Mantet variety, the most susceptible to the development of scab in the conditions of the experiment.

Efficiency of biological preparations against scab and powdery mildew of apple trees

. Scab (caused by Venturia inaequalis Cooke (Wint.)) and powdery mildew (Podospaera leucotricha (Ellis & Everh. Salmon)) are harmful diseases of the apple tree, the protection against which is based on repeated spraying with chemical fungicides. To reduce the pesticide burden on agrocenoses, the use of biological protection products is relevant. The purpose of this study was to investigate the effectiveness of biological preparations based on fungi and bacteria (mycoparasites and antagonists) against scab and powdery mildew of apple trees. For this, a set of methods was used, including phytopathological diagnostics and disease monitoring, phenological observations, yield recording, and statistical analysis. The biological preparations Ampelomycin BT (6 l/ha) based on the fungus of the genus Ampelomyces Ces ex Shlecht., Gliocladin BT (10 l/ha), which contains mycelium and spores of the fungus of the genus Gliocladium, and Fluorescin BT (8 l/ha), which is based on bacteria of the genus Pseudomonas, were investigated. Their use led to a decrease in the spread and development of apple scab, and the technical efficiency of the preparations ranged from 68% to 79%. The biological preparations also reduced the damage to plants by the powdery mildew pathogen with a technical efficiency of 59-76%. Treatment of apple plants with Gliocladin BT, Ampelomycin BT, and Fluorescin BT reduced the number of scab-affected fruits by 22.7-35.6%. The technical effectiveness of the preparations was 62-78%. The use of the biological preparations under study ensured the preservation of the yield within 3.7-4.4 t/ha. The results obtained indicate the prospects of using biological preparations against scab and powdery mildew of apple trees for the ecologisation of plant protection

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.

Efficiency of using tank mixtures of fungicides for the control of phytopathogens in potato agrocenoses

Goal. To evaluate the level of effectiveness of phytopathogen control elements in agrocenoses of potatoes for different combinations of pesticides with biologically active substances, methods of application and the reaction of Aria potatoes to them.
 Methods. Field — for monitoring the main diseases of potatoes in field experiments, recording the harvest, determining the effectiveness of combinations of fungicides with plant growth regulators and microfertilizers; laboratory — for recording damage to tubers by diseases. Research was conducted in accordance with generally accepted methods.
 Results. In 2019—2021, the Laboratory of Plant Immunity and Protection of the Institute of Potato Breeding of the National Academy of Sciences conducted research on the improvement of elements of phytopathogen control technology in potato agrocenoses under various schemes of using tank mixtures of fungicides, growth regulating substances (RRS) and microfertilizers. The research used the Aria variety selected by the institute. The lowest level of development of Alternaria was in the version where tuber treatment was carried out (fungicide impregnant + microfertilizer + PPR) and two plant treatments (Kurzat R + microfertilizer + PPR). The development of the disease was 14.7% for the spread of 66.6%, and the technical efficiency of the protection elements was 68.8%. To effectively control the development of common scab, rhizoctoniosis and fusarium dry rot, it is advisable to treat tubers with a tank mixture of impurity-fungicide + PPR + microfertilizer and to treat plants with a mixture of Kurzat P + PPR + microfertilizer, which significantly reduces the level of tuber disease control and limits their spread compared to and chemical standards. The yield of potatoes in the variants was higher than in the control (25.4 t/ha) — 29.8—36.8 t/ha. The level of the preserved harvest compared to the control was in the range of 4.4—11.4 t/ha or 17.3—44.9%. The highest level of yield (36.8 t/ha) was in the variant: treatment of tubers — impregnation-fungicide + micro-fertilizer + PPR and two plant treatments — Cuproxate + micro-fertilizer + PPR. This indicator is 11.4 t/ha (44.9%) higher than the control and 4.7 t/ha (14.6%) higher than the standard.
 Conclusions. The use of tank mixtures of fungicides with a growth regulator and microfertilizer significantly reduces the level of potato diseases and increases the yield. It was established that the use of a mixture of impurity-fungicide + PPR + microfertilizer for treating potato tubers and Kurzat P + microfertilizer + PPR for treating plants significantly reduces the level of common scab, rhizoctoniosis and fusarium dry rot and limits their spread, compared to control and chemical standards.

Development of common scab in potato cv. Kufri Pukhraj in Indian Punjab is influenced by scab lesion severity on seed tubers and duration of crop in the field

Development of common scab in potato cv. Kufri Pukhraj in Indian Punjab is influenced by scab lesion severity on seed tubers and duration of crop in the field

Protection of the apple tree from scab in the Republic of Tatarstan

The purpose of the research is a comparative assessment of the use of the biological preparation «Baktofit» and the chemical preparation «Skor» in the protection of apple plants from scab in the conditions of the Republic of Tatarstan. The scab susceptibility of apple cultivars was assessed according to the methodology of the All-Russian Scientific Research Institute of Fruit Crop Breeding. The weather conditions of the spring–summer period of 2021 in the Tenkovsky Department of Horticulture of the Tatar Research Institute of Agriculture had a negative impact on the development and spread of scab on the leaves and fruits of the Kamskaya, Tenkovskaya and Renet Tatarsky apple tree varieties. Average for 2020-2021 The chemical drug «Sko» turned out to be much more effective than the biological drug «Baktofi» in protecting apple leaves from scab. Three-way analysis of variance showed that the share of the influence of drugs (factor A) on the damage of leaves by scab is 48.0%, genotypes of varieties (factor B) - 13.4%, conditions of the year (factor C) - 13.0%, interactions of factors A and C - 0.6%, interactions of factors B and C - 18.1%. Average for 2020-2021 the chemical drug «Skor» turned out to be significantly more effective than the biological drug «Baktofit» in protecting apple fruits from scab. Three-factor analysis of variance showed that the share of the influence of drugs (factor A) on fruit damage by scab is 49.5%, genotypes of varieties (factor B) - 24.2%, conditions of the year (factor C) - 8.4%, interactions of factors A and C - 1.9%, interactions of factors B and C - 11.7%.

Susceptibility of pecan cultivars to Venturia effusa in Uruguay

Pecan scab caused by Venturia effusa is the main crop disease affecting leaves and fruits, resulting in defoliation and yield and fruit quality losses. Recently, pecan groves expanded into Uruguay, Brazil and Argentina, where the temperate-humid climate is conducive for scab development. Chemical control is difficult given the height of adult trees which exceeds 20 m. Therefore, the strategy consists on selecting tolerant cultivars accompanied by cultural management aimed at providing a good ventilation and light interception. The objective of this work was to assess the susceptibility of pecan cultivars to Venturia effusa in the Uruguayan agroclimatic conditions. Disease severity index (DSI) in fruits and leaves were determined in 18 cultivars throughout four consecutive seasons. Most of the cultivars evaluated were classified as resistant with fruit disease severity index (DSIF) below 2.0, being Elliott and Sumner the most resistant ones (DSIF < 1.5) while Mahan was susceptible (DSIF > 3.0) and Apache and Wichita were very susceptible (DSIF > 4.5)

Biological method of protection of apple trees from green apple aphids and apple scab in the conditions of the Pre-Carpathian province of the Carpathian mountain zone of Ukraine

Goal. To study the effectiveness of biological preparations to reduce the number and harmfulness of green apple aphids, as well as to reduce the spread and development of apple scab in apple orchards of the Precarpathian province of the Carpathian mountain zone of Ukraine.&#x0D; Methods. Experiments to determine the technical and economic efficiency of biological protection of apple trees, study the phytosanitary status of apple orchards were conducted in 2016—2020 in the apple orchard of the Ukrainian Plant Quarantine Research Station of the Institute of Plant Protection of NAAS on apple orchards in 2005. Accounts for phytophagous population and the presence and development of diseases were carried out according to generally accepted methods in accordance with the phases of the host plant. The effectiveness of insecticides was determined by official methods in 2 and 7 days according to the formula of Henderson and Tilton, the effectiveness of fungicides — in 7 days. Statistical processing of research results was performed by the method of analysis of variance. Plant yield was determined during the third decade of September.&#x0D; Results. The use of the studied bioinsecticides and their mixtures reduced the number of green apple aphids by 61.1—76.8% and provided, in comparison with the control, an increase in the yield of apple orchards by 1.7—1.9 t/ha while improving the marketable quality of fruits. The use of the studied biofungicides and their mixtures allowed to reduce the spread and development of scabies on apple leaves by 66.5—72.5% and on apple fruits by 68.7—73.3%. Due to the use of the studied biofungicides, the yield of orchards was 1.7—2.5 t/ha more than the control and increased the amount of first-class fruit products by 9.5—20.0% compared to the control and reduced the number of non-standard fruits by 11.3—14.8%.&#x0D; Conclusions. Evaluation of the effectiveness of the studied bioinsecticides and biofungicides in apple orchards showed that all drugs allow to effectively control the number of green apple aphids and the spread and development of apple scab in the Precarpathian province of the Carpathian mountain zone of Ukraine.

Ефективність застосування біологічних засобів проти хвороб на яблуні (Malus domestica Borkh.)

The author presents results of the two-year researching (2019-2020) the effectiveness of the biological means (PhytoHelp, MikoHelp, Kazumin 2L, RK, Cydox Pro, LS-1, Micro-Mineralis (universal) Plus, RK, Phytocid-r) against scab and apple fruit rot. The crop protection is limited almost as a whote to narrowing the spread and development of scab, all spraying was carried out the because of risk of the apple scab infection. The analysis of the weather conditions and instrumental monitoring of the epiphytic situation was conducted during April-August. There were 15 critical periods of the scab infection in 2019 and 2020. Respectively 5 and 4 sprays of the trees were made with experimental preparations. The analysis of the diseases spread and development the studing areas showed that all the preparations had a deterrent effect against apple scab, but higher results were obtained with the use of Kazumin, Fitohelp, MikoHelp and Fitocid-r. The development of this disease on the leaves as compared to the control variant decreased by nesrly 3-7 times( 1.4-6.1 % on the average). The efficiency of these preparations was 71-86 %. The development of scab when utilizeng LS 1 and Cydox Pro well as the fertilizers Micro-Mineralis Plus was 2.7-3 times less than in control, and their technical effectivity was 61-70 %. Casumin and Phytocid-r, which were 72-75 % effective, coped better with limiting the scab spread. With the application of Micro-Mineralis Plus worse the results were - only 41 %. The observations over fruit rot showed a low prevalence of the disease in all the experiment treatments. Nerely a few rotten fruits were defected. In the control variant without the use of where the fungicides, were fruit damage was 11 %, while in other variants this findex did not exceed 2 %, and the technical efficiency of the experimental preparations ranged from 79 to 100 %.

ASSESSMENT OF INTRODUCED APPLE VARIETIES BY SCAB AFFECTION (VENTURIA INAEQUALIS (COOKE) G. WINTER)

The article presents data on the identifying of apple varieties resistant to scab for their further use in breeding. The research was carried out on the basis of the Orenburg branch of the Federal Horticultural Research Center for Breeding, Agrotechnology and Nursery from 2010 to 2020 in the orchard established in 2004. The objects of research were introduced apple varieties and local hybrids. Scab (the causative agent is the marsupial mushroom Venturia inaequalis (Cooke) G. Winter) causes great damage to the apple tree. This disease affects the fruits and leaves, while dramatically reducing the apple productivity and marketability. According to the results of the studies, the greatest development of scab was observed in 2011, 2013 and 2016. In dry years (2010, 2012, 2014, 2015, 2017-2020 years) scab lesions were not observed. We have identified apple introduced varieties, which over the years of observation had a weak scab lesion and few spots on the apple leaves. In the control variant, in summer varieties in 2011, the scab on the leaves of the Serebryanoe kopytse variety was 0.9 points, all other studied varieties had a lower parameter. In autumn varieties, the varieties Sverdlovchanin and Gornist had the lowest parameter — 0.3-0.4 points, respectively, with a control parameter of 0.8 points (Prizemlennoye variety); in winter varieties, all the studied samples were lower than the control variant — 0.9 points. Weather conditions 2013 and 2016 also showed apple varieties less susceptible to scab in the conditions of the Orenburg region. As a result, we identified apple varieties that are weakly affected by scab: summer varieties — Letneye polosatoye, Mechtatel’nitsa, Solntsedar, Chudnoye; autumn varieties — resident of Sverdlovsk, Hornist; winter — Anis Sverdlovsky, Krasa Sverdlovsk, Persian. The obtained data can be used in breeding to create new apple varieties resistant to scab in the conditions of the Orenburg region.

Antagonism of Bacillus thuringiensis to phytopathogenic micromicetes as pathogens of apple trees

Antagonistic microorganisms, producing bactericidal and fungicidal substances, spread in space and occupy various ecological niches. Antagonistic action of microorganisms can be combined with a number of other properties that can be used by humans for their own purposes. Microorganisms — agents of biological products often have a multifunctional effect on the components of the agroecosystem, which under the influence of various environmental factors could have positive and negative consequences. The aim of the study was to study the effect of new highly active entomopathogenic strains of Bacillus thuringiensis on non-target objects — components of the biocenosis of the apple orchard. When developing technologies for biocontrol of the number of apple trees pests using B. thuringiensis revealed an additional positive protective effect — reducing the number of pathogens of fungal diseases on the leaf surface. Treatment of apple leaves with a liquid culture of strain B. thuringiensis 0376 after 72 hours of application reduced the number of scab of Fusicladium dendriticum by 7 times, and the pathogen of monolisis of Monilia fructigena — 9 times. Strain B. thuringiensis 0371 showed the highest level of antagonism, because in vitro completely inhibited the growth and development of micromycetes on the surface of the nutrient medium. On the leaf surface, the application of culture strain 0371 reduced the number of Fusicladium dendriticum by 92%, and Monilia fructigena — by 86% after 72 hours of treatment. In a field experiment when treating apple trees with a culture of this strain, scab development decreased by 7.1%. Strain B. thuringiensis 787 did not show antagonism against phytopathogenicmicromycetes during co-cultivation on nutrient medium, which may be explained by its inability to produce water-soluble exotoxin, in contrast to strains of B. thuringiensis, which are antagonists of scab and apple monolisis. Strain B. thuringiensis 0371 requires further research and development of its formulations, because it is promising for the creation of a complex biological product with insect-fungicidal properties for use in ecological and agriculture friendly technologies.

Effect of prohexadione calcium on vegetative growth, yield and scab development on ‘Sinap Orlovskii’ apple trees

There are many apple orchards in the Russian Federation where trees were trained with volumetric canopies; the vigor of these canopies must be suppressed. Prohexadione calcium (calcium 3-hydroxy-5-oxo-4-propionyl-cyclohex-3-enecarboxylate) was developed to inhibit the gibberellins biosynthesis to reduce vegetative growth. The study was done in the commercial orchard of “Planeta sadov” LLC in Michurinck district of Tambov Region (53°02’11.9 “N 40°29’29.9 “E). This research was aimed to evaluate the influence of prohexadione calcium on the length of one-year shoot growth, yield, and scab development on trees of vigorous apple cultivar ‘Sinap Orlovskii,’ planted 6 x 4 m (418 tr. ha-1). After 1.25 + 1.25 g ha-1 prohexadione calcium double treatment, the length of one-year shoots was 1.96 (2019) and 1.60 (2020) times less than Control 1 (without prohexadione calcium application and hand pruning) and 2,00 times less than in hand pruning treatment. The application of prohexadione calcium inhibited apple tree height and reduced the average height growth rate by 10.7% (2019) and 17.0% (2020). Growth retardant treatments stimulated significant yield increases and improved the commercial value of fruits. The enhance of scab protection improved under the influence of prohexadione calcium treatments. The application of growth retardant increased the alternate bearing index.

New apple-tree (Malus domestica Mill.) varieties as sourses of breeding valuable traits

Aim. To identify sources of several valuable economic and biological traits among new Ukrainian and foreign cultivars. Results and Discussion. The weather in the spring of 2019 and 2020 contributed to the epiphytotic development of scab, which allowed for assessment of susceptibility of new cultivars to this disease and for identification of sources of high resistance to it. There were no pathogen signs in immune cvs. Harant, Goldrush, Topaz, and William's Pride, which are carriers of the scab resistance oligogen (Vf). No cultivars that would be consistently highly-resistant to this disease in the field have been found. The creation of cultivars with a columnar crown remains a promising trend in breeding. Cv. Ruslan is a columnarity source. As to fruit yield, the leaders were Elise, Geneva Early, Goldrush, Honeycrisp, Pilot, and Topaz. Cvs. Harant, Ruslan, Elise, William's Pride gave stable fruit yields. Cvs. Kakhovske, Alionushkino, Julia, Honeycrisp, and Topaz give yields every year. Cvs. Harant, Malakhit and Rubin are sources of large fruits. Cv. Harant is noticeable for stable expression of this trait, which makes it a reference of large fruits. Mid-sized apples are considered the most optimal for selling. The sources of this trait are cvs. Ruslan, Elise, Honeycrisp, Szampion Arno, and Topaz. Most of the studied cultivars have round or flat-round fruits. Kakhovske apples are distinguished by their unordinary oval (sinapoid) shape. Sources of several features that determine highly-attractive appearance of their fruits have been distinguished. These are cvs. Harant, Malakhit, Ruslan, Elise, Geneva Early, Honeycrisp, Rubin, and William's Pride. Apples of cvs. Kakhovske, Elise, Honeycrisp, Rubin, and William's Pride are characterized by excellent palatability. Cultivars that are sources of several valuable economic and biological traits have been selected. Conclusions. Modern apple cultivars are starting material for creating new cultivars that will meet the future requirements. Cvs. Harant, Ruslan, Elise, Honeycrisp, Topaz, and William's Pride are sources of the maximum number of selectively valuable traits. By crossing them with cvs. Kakhovske, Malakhit, Alionushkino, Geneva Early, Goldrush, Julia, Pilot, and Rubin, it is possible to obtain genotypes with various ripening periods, which would combine immunity to scab, compact crown, high and stable yield, and high quality fruits.

Antifungal Activity of Alpha-Mangostin against Colletotrichum gloeosporioides In Vitro and In Vivo.

We investigated alpha-mangostin (α-mangostin, α-MG), a xanthone natural product extracted from the pericarp of mangosteen (Garcinia mangostana), for its antifungal activities and possible mechanism against Colletotrichum gloeosporioides, which causes mango anthracnose. The results demonstrated that α-MG had a relatively high in vitro inhibitory activity against C. gloeosporioides among 20 plant pathogenic fungi. The median effective concentration (EC50) values of α-MG against mycelial growth were nearly 10 times higher than those of spore germination inhibition for both strains of C. gloeosporioides, the carbendazim-sensitive (CBD-s) and carbendazim-resistant (CBD-r). The results suggested that α-MG exhibited a better inhibitory effect on spore germination than on the mycelial growth of C. gloeosporioides. Further investigation indicated that the protective effect could be superior to the therapeutic effect for mango leaves for scab development. The morphological observations of mycelium showed that α-MG caused the accumulation of dense bodies. Ultrastructural observation further revealed that α-MG caused a decrease in the quantity and shape of the swelling of mitochondria in the mycelium cells of C. gloeosporioides. In addition, bioassays disclosed that the inhibitory activity of α-MG on spore germination was reduced by adding exogenous adenosine triphosphate (ATP). These results suggested that the mode of action of α-MG could be involved in the destruction of mitochondrial energy metabolism. The current study supports α-MG as a natural antifungal agent in crop protection.

Assessing the suppressive effects of biopesticides and phosphite on common scab development in potatoes

ABSTRACT Potato common scab (CS) is caused by several saprophytic bacteria of the genus Streptomyces, including Streptomyces scabies. Various methods have been investigated to control CS, but their efficiency is usually low. Biopesticide formulations, including bacteria from the Bacillus spp., are increasingly used to control soil pathogens. Two Bacillus-based products, Double Nickel 55TM and Microflora PROTM, and the phosphite-based fungicide PhostrolTM, alone or in combination, were examined to determine their effects on CS development on tubers of the potato cultivars Red Pontiac, Prospect, Green Mountain, and Goldrush. CS disease incidence and severity were assessed using 4 parameters: percentage of tuber area covered by CS, necrotic areas, the number of deep pits and of shallow pits. The effects of treatments on tuber periderm morphology were assessed by determining the number of suberised cell layers and the thickness of suberised cell layers. Cultivar Goldrush performed much better than the other three cultivars, in all parameters scored. Among the six treatments, only Double Nickel 55TM + PhostrolTM reduced CS more consistently. Suberised cell size, shape, arrangement, number of layers, and phellem thickness, were found to vary largely across cultivars. A thicker phellem, but not the number of cells in the phellem, was found to be associated with improved resistance to CS. Treatments had limited effect on the number of layers of suberised cells and phellem thickness and these effects seemed to be cultivar specific. Overall, Double Nickel 55TM and Microflora PROTM were found to augment the number of suberised cell layers.