scholarly journals Efficacy of Sterol-Inhibiting Fungicides on the Control of Scab Disease (Venturia Inaequalis) in Apple Tree

2019 ◽  
Vol 4 (6) ◽  
pp. 101-103
Author(s):  
Edlira Shahinasi ◽  
Ferdi Brahushi
Keyword(s):  
Untreated Control ◽  
Apple Tree ◽  
Venturia Inaequalis ◽  
Apple Scab ◽  
Disease Index ◽  
Golden Delicious

Apple scab, caused by Venturia Inaequalis is one of the most problematic diseases of apples in Korça region. The control of this disease requires different applications of fungicides. The aim of the study was the estimation of efficacy of sterol-inhibiting fungicides such as myclobutanil and penconazole on the control of scab disease. The effectiveness of fungicides was evaluated for two cultivars Golden Delicious and Starking and the minimum and the maximum recommended doses were applied. The obtained results showed that scab prevalence in leave ranges from 79.2% to 85.6% respectively in untreated trees of Golden Delicious and Starking cultivars. The scab prevalence of leaves in apples treated with pesticides ranges from 18.1% in Golden Delicious cultivar to 22.2% in Starking cultivar, meanwhile the scab prevalence in fruit varies from 4.2% in Starking cultivar to 6.1% in Golden Delicious cultivar.  The disease index of leave in untreated control varies from 38.4% to 40.1% respectively for Golden Delicious cultivar and Starking cultivar, while the severity of fruit in untreated trees varies from 45.6% in Starking cultivar to 49.0% in Golden cultivar. Therefore, the data showed that the uses of sterol-inhibiting fungicides were effective in the control of scab disease.

scholarly journals A New Phytosanitary Method to Reduce the Ascospore Potential of Venturia inaequalis

Plant Disease ◽  
2017 ◽  
Vol 101 (3) ◽  
pp. 414-420 ◽  
Author(s):  
Franziska M. Porsche ◽  
Barbara Pfeiffer ◽  
Andreas Kollar
Keyword(s):  
Leaf Litter ◽  
Yeast Extract ◽  
Untreated Control ◽  
Venturia Inaequalis ◽  
Apple Scab ◽  
Nutrient Media ◽  
Apple Leaves ◽  
Litter Decay ◽  
Ascospore Discharge ◽  
Infection Pressure

Ascospores of Venturia inaequalis, released from pseudothecia in overwintered, infected apple leaves, serve as the primary inoculum for apple scab. In this study, we tested a new sanitation strategy to reduce ascospore inoculum under orchard conditions over three overwintering periods. After leaf fall, nutrient media containing different concentrations of degraded casein or a yeast extract from Saccharomyces cerivisiae were applied to leaf litter infected with apple scab. The application of 30 and 60% yeast extract showed the greatest efficacy, and significantly reduced ascospore discharge by 99% (P < 0.01) in 2013 and 2014. The efficacy of the treatments did not differ from treatment with 5% urea (P > 0.05). Leaf litter decay was accelerated in the plots treated with yeast extract compared with untreated control plots. Moreover, apple leaves treated with yeast extract had completely decayed due to earthworm activity before ascospore maturity. In comparison, up to 26% of the leaves in untreated control plots had not decayed. These results suggest that the treatment of leaf litter with yeast extract can almost completely eliminate apple scab inoculum in the course of the whole primary season. These sanitation practices may be beneficial for both organic and conventional cultivation. The reduced infection pressure may allow growers the usage of fungicides with lower efficacy or to reduce the number of applications needed to manage apple scab in spring.

scholarly journals Organic apple growing using sanitation treatments against apple scab

2007 ◽  
Vol 13 (1) ◽  
Author(s):  
F. Abonyi ◽  
I. J. Holb
Keyword(s):  
Untreated Control ◽  
Primary Infection ◽  
Venturia Inaequalis ◽  
Apple Scab ◽  
Apple Orchard ◽  
Apple Cultivar ◽  
Lime Sulphur ◽  
Fallen Leaves

Effects or sanitation practices were evaluated on primary and autumn infection by Venturia inaequalis in an organic apple orchard at Eperjeske on the moderately scab-susceptible apple cultivar Jonathan in 2005 and 2006. Evaluated sanitation practices were: i) collection of fallen leaves in autumn; ii) destroying fallen leaves by disc cultivation in autumn; iii) spraying fallen leaves with 2% lime sulphur in autumn; iv) spraying fallen leaves with 2% lime sulphur in autumn and then collection of fallen leaves in autumn; and v) untreated control. In both years, most sanitation practices reduced significantly (P< 0.05) scab incidence in the primary infection periods compared to untreated control. The highest leaf scab incidence was observed in the untreated plots (26:2 and 24.3% in 2005 and 2006, respectively), while the lowest was in the treatments of spraying fallen leaves with 2% lime sulphur combined with collection of fallen leaves (11.7 and 12.3% in 2005 and 2006, respectively).

scholarly journals 510 Impact of a Reduced Fungicide Program on `Liberty' Apple Tree Vigor, Productivity, and Fruit Quality

HortScience ◽  
2000 ◽  
Vol 35 (3) ◽  
pp. 482E-482
Author(s):  
L.P. Berkett ◽  
M.E. Garcia ◽  
J. Clements ◽  
G. Neff
Keyword(s):  
Fruit Quality ◽  
Apple Tree ◽  
Venturia Inaequalis ◽  
Apple Scab ◽  
Quality Data ◽  
Apple Cultivars ◽  
Show Difference ◽  
Repeated Applications ◽  
Marketable Fruit ◽  
Important Disease

Apple scab, a fungal disease caused by Venturia inaequalis, is considered the most important disease of apple worldwide. The disease can be devastating, causing reduction in yield or making the apples unfit for the market. Currently, the production of marketable fruit from scab susceptible cultivars depends on the repeated applications of fungicides. Scab-resistant apple cultivars, which are genetically immune to apple scab, can offer a biological alternative to fungicide use. `Liberty,' was bred for immunity to apple scab; however, it is not immune to other apple diseases and pests. Research has been conducted during a 3-year project (1996–1998) to determine whether reduced fungicide programs adversely affect overall tree vigor, productivity, and fruit quality. Data collected include tree vigor (TCSA and time of leaf abscission), tree productivity (YE), and fruit quality (fruit firmness and disorders during storage). Results indicate no significant differences between the two treatments (reduced fungicide and no fungicide application) in most of the parameters measured. Based on fruit that were harvested and graded to commercial standards, the estimated gross monetary value of the crop does not show difference between treatments. These results could translate into an economic advantage for growers when one factors in the savings in fungicide purchases. In addition, there are also health and environmental advantages to reduced fungicide usage.

scholarly journals Effect of Leaf Wetness Duration, Temperature, and Conidial Inoculum Dose on Apple Scab Infections

Plant Disease ◽  
1999 ◽  
Vol 83 (6) ◽  
pp. 531-534 ◽  
Author(s):  
J. R. Hartman ◽  
L. Parisi ◽  
P. Bautrais
Keyword(s):  
Venturia Inaequalis ◽  
Disease Incidence ◽  
Apple Scab ◽  
The Other ◽  
Leaf Wetness ◽  
Leaf Wetness Duration ◽  
Inoculum Dose ◽  
Golden Delicious ◽  
Wetness Period ◽  
Series Of Experiments

Apple seedlings (2 months old, ‘Idared’ × ‘Golden Delicious’) were inoculated with conidia of Venturia inaequalis in order to study the effects of inoculum dose and leaf wetness duration on development of apple scab symptoms. For each experiment, the C3 curve (indicating heavy infection levels) was used as the basis for relating infection to temperature and leaf wetness duration. In one series of experiments, seedlings were treated with inoculum doses of 1.5, 5.4, 15.6, 32.2, 81.2, and 250 × 103 conidia/ml and leaves were kept wet during C3 infection periods at temperatures of 6, 11, 16, and 22°C. At all four temperatures, disease incidence (scab lesions/plant) increased with increasing inoculum doses up to about 81.2 × 103 conidia/ml. Disease incidence was lower at 22°C than at the other temperatures. In a second series of experiments, seedlings inoculated with 10 × 103 conidia/ml were kept moist for infection periods ranging from 0.6 to 2.0 times the C3 leaf wetness duration curve at 6, 11, 16, and 22°C. Disease incidence increased with increasing duration of leaf wetness and generally leveled off between 150 and 200% of the C3 curve. At this inoculum dose (10 × 103 conidia/ml), doubling the leaf wetness duration indicated by the C3 curve resulted in high disease incidence, similar to levels obtained with a higher inoculum (250 × 103 conidia/ml) and shorter wetness period (1.0 C3).

scholarly journals Effect of Pruning on Apple Scab in Organic Apple Production

Plant Disease ◽  
2005 ◽  
Vol 89 (6) ◽  
pp. 611-618 ◽  
Author(s):  
I. J. Holb
Keyword(s):  
Apple Tree ◽  
Spray Deposition ◽  
Venturia Inaequalis ◽  
Apple Scab ◽  
Tree Canopy ◽  
Consistent Difference ◽  
Progress Curve ◽  
Biological Interpretation ◽  
Apple Cultivars ◽  
Apple Production

In a 3-year Hungarian study, the effectiveness of apple tree pruning as a management tactic for control of apple scab (Venturia inaequalis) was investigated on two susceptible (cvs. Jonagold and Mutsu), two moderately susceptible (cvs. Elstar and Idared), and two Vf resistant apple cultivars (cvs. Liberty and Prima) in three high-density organic apple orchards treated with copperand sulfur-based fungicide programs. The area under the disease progress curve (AUDPC) for leaf and fruit incidences was calculated to evaluate three winter pruning treatments (unpruned, weakly pruned, and strongly pruned). Strong pruning significantly decreased leaf scab on the susceptible and the moderately susceptible cultivars at all sites compared with unpruned ones. Moreover, for the cultivar Jonagold in all years and for the cultivar Mutsu in 2001, AUDPC values of strongly pruned trees were significantly lower at P = 0.05 compared with the weaklypruned trees. The effect of pruning on development of fruit scab was weaker than on leaf scab in all years and at all sites. For fruit scab incidence on susceptible cultivars, only strong pruning treatments decreased AUDPC significantly compared with unpruned treatments. The effects of pruning treatments on moderately susceptible cultivars were significant only in 2001 at all sites. Resistant cultivars showed no significant effect of pruning treatments on development of either fruit or leaf scab except for cultivar Liberty in 2001 at one site. Pruning resulted in no consistent difference in the apple tree canopy microclimate. However, strong pruning resulted in improved spray deposition in the tree canopy when applications were made with an airblast sprayer at midsummer. Results are compared with similar studies, and their biological interpretation is discussed.

EXPERIMENTAL DATA ON CHEMICAL CONTROL OF MAIN PATHOGENS AND PESTS IN AN APPLE ORCHARD IN NORTHEASTERN ROMANIA IN 2019

2020 ◽  
Vol 13 ◽  
pp. 105-109
Author(s):  
Cristina Ionela Turcu ◽  
Agurița Aftudor Manolache ◽  
Ionel Perju ◽  
Simona Mihaela Chelaru ◽  
Margareta Corneanu
Keyword(s):  
Venturia Inaequalis ◽  
Cydia Pomonella ◽  
Apple Scab ◽  
Apple Orchard ◽  
Climatic Conditions ◽  
Research Station ◽  
Pest Species ◽  
North Eastern ◽  
Golden Delicious ◽  
Fruit Growing

"The researches were carried out in 2019 in an apple plantation with Jonathan, Golden Delicious, Starkrimson varieties grafted on MM106 in the fields of the Fălticeni Development Centre belonging to the Development Research Station for Fruit Growing Iași (North Eastern Romania). The climatic conditions in 2019 were favorable for the development of pathogens Venturia inaequalis, Podosphaera leucotricha and Monilinia fructigena. In the conditions of fungicide treatments, the varieties sensitive to apple scab on fruits were Starkrimson and Golden Delicious with an attack degree between 4.5 and 10.5%. Pest species Cydia pomonella and Adoxophyes reticulana showed a frequency of attack of 45% and 15%, respectively in the case of untreated control. The results of the studies highlight the importance of applying phytosanitary treatments correlated with climatic conditions and resistance of varieties to the attack of diseases and pests."

scholarly journals Role of organosilicone surfactant in apple scab control under scab conducive weather conditions

2008 ◽  
Vol 14 (3) ◽  
Author(s):  
I. J. Holb
Keyword(s):  
Untreated Control ◽  
Venturia Inaequalis ◽  
Apple Scab ◽  
Weather Conditions ◽  
Fruit Production ◽  
Application Of Surfactants ◽  
Fungus Infection ◽  
Scab Control ◽  
Integrated Fruit Production ◽  
Organosilicone Surfactant

Fungicides of integrated fruit production (dithianon, captan, and diclofluanid) and an organosilicone surfactant were compared in spray schedules from green tip until summer in order to control apple scab caused by Venturia inaequalis and to evaluate their phytotoxicity on fruit. Sixteen sprays of 1.8 kg ha-1captan, 0.41 ha-1 dithianon, and 1.8 kg ha-1 diclolfluanid significantly (P=0.05) reduced the incidence of leaf or fruit scab compared to unsprayed products. All fungicides applied with organosilicone at 0.1% resulted in lower incidence of scab on young and older leaves as well as on harvested fruit, but these were not statistically always better than fungicides applied alone. In case of diclofluanid, the fungicide applied with organosilicone at 0.1% resulted in significantly lower (P = 0.001) incidence of scab on young and older leaves. Diclofluanid applied with organosilicone at 0.1% gave the best scab control on leaf and fruit. Treatments applied with fungicides alone had no significant effect on plant phytotoxicity compared to untreated control. All fungicides applied with organosilicone at 0.1% increased (P = 0.05) fruit damage compared to untreated control or fungicide applied alone, though these were not always significantly different. In case of percentage of fruit russet, treatment of dithianon 0.4 1/ha + 0.1% organosilicone significantly increased fruit russet, while fruit russet index significantly increased in the treatment of diclofluanid 1.8 kg/ha + 0.1% organosilicone compared to untreated control. In sum, application of surfactants can help to increase efficacy of scab fungicides; and consequently, to reduce the risk of fungus infection under high scab disease pressure. This fact may also be helpful in fungicide resistance management and reduced-spray programs with accurate scab warning systems.

Constituents from Morus root bark against Venturia inaequalis – the causal agent of apple scab

Planta Medica ◽  
2007 ◽  
Vol 73 (09) ◽  
Author(s):  
JM Rollinger ◽  
R Spitaler ◽  
M Menz ◽  
P Schneider ◽  
EP Ellmerer ◽  
...  
Keyword(s):  
Venturia Inaequalis ◽  
Apple Scab ◽  
Causal Agent ◽  
Root Bark

scholarly journals Apple Autotetraploids with Enhanced Resistance to Apple Scab (Venturia inaequalis) Due to Genome Duplication-Phenotypic and Genetic Evaluation

2021 ◽  
Vol 22 (2) ◽  
pp. 527
Author(s):  
Małgorzata Podwyszyńska ◽  
Monika Markiewicz ◽  
Agata Broniarek-Niemiec ◽  
Bożena Matysiak ◽  
Agnieszka Marasek-Ciolakowska
Keyword(s):  
Venturia Inaequalis ◽  
Leaf Shape ◽  
Apple Scab ◽  
Early Period ◽  
Physiological Parameters ◽  
Aflp Analysis ◽  
Poor Growth ◽  
Enhanced Resistance ◽  
Apple Cultivars ◽  
Old Trees

Among the fungal diseases of apple trees, serious yield losses are due to an apple scab caused by Venturia inaequalis. Protection against this disease is based mainly on chemical treatments, which are currently very limited. Therefore, it is extremely important to introduce cultivars with reduced susceptibility to this pathogen. One of the important sources of variability for breeding is the process of polyploidization. Newly obtained polyploids may acquire new features, including increased resistance to diseases. In our earlier studies, numerous tetraploids have been obtained for several apple cultivars with ‘Free Redstar’ tetraploids manifesting enhanced resistance to apple scab. In the present study, tetraploids of ‘Free Redstar’ were assessed in terms of phenotype and genotype with particular emphasis on the genetic background of their increased resistance to apple scab. Compared to diploid plants, tetraploids (own-rooted plants) were characterized with poor growth, especially during first growing season. They had considerably shorter shoots, fewer branches, smaller stem diameter, and reshaped leaves. In contrast to own-rooted plants, in M9-grafted three-year old trees, no significant differences between diplo- and tetraploids were observed, either in morphological or physiological parameters, with the exceptions of the increased leaf thickness and chlorophyll content recorded in tetraploids. Significant differences between sibling tetraploid clones were recorded, particularly in leaf shape and some physiological parameters. The amplified fragment length polymorphism (AFLP) analysis confirmed genetic polymorphism of tetraploid clones. Methylation-sensitive amplification polymorphism (MSAP) analysis showed that the level of DNA methylation was twice as high in young tetraploid plants as in a diploid donor tree, which may explain the weaker vigour of neotetraploids in the early period of their growth in the juvenile phase. Molecular analysis showed that ‘Free Redstar’ cultivar and their tetraploids bear six Rvi genes (Rvi5, Rvi6, Rvi8, Rvi11, Rvi14 and Rvi17). Transcriptome analysis confirmed enhanced resistance to apple scab of ‘Free Redstar’ tetraploids since the expression levels of genes related to resistance were strongly enhanced in tetraploids compared to their diploid counterparts.

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