Chaetomium globosum antagonizes the apple scab pathogen, Venturia inaequalis, under field conditions

1984 ◽  
Vol 62 (9) ◽  
pp. 1814-1818 ◽  
Author(s):  
Daniel Cullen ◽  
Flora M. Berbee ◽  
John H. Andrews
Keyword(s):  
Aureobasidium Pullulans ◽  
Venturia Inaequalis ◽  
Apple Scab ◽  
Leaf Tissue ◽  
Chaetomium Globosum ◽  
Minimum Concentration ◽  
Growing Seasons ◽  
Ascospore Germination ◽  
Colony Forming Units ◽  
Leaf Surfaces

During the 1981 and 1982 growing seasons, Aureobasidium pullulans (de Bary) Arnaud and Chaetomium globosum Kunze: Fr. spore suspensions were applied to apple saplings in an orchard at 1- to 2-week intervals to control the apple scab pathogen, Venturia inaequalis (Cke.) Wint. (anamorph, Spilocaea pomi Fr.). Population densities of applied antagonists were monitored during 1982 trials by dilution plating of leaf washings onto selective media. Aureobasidium pullulans and C. globosum populations averaged 54 and 314 colony-forming units (CFU) per milligram of leaf tissue 3 h after application and declined to means of 15.9 and 35.7 CFU mg−1, respectively, before the next application. Relative to buffer controls, spore suspensions of A. pullulans were only slightly antagonistic to V. inaequalis infection, but C. globosum ascospore suspensions reduced scab more than 20% in both years. Light and scanning electron microscope examination of leaf surfaces following inoculation of seedlings in growth chambers showed a 25% increase in C. globosum ascospore germination on scab-infected tissue relative to healthy tissue. The minimum concentration of C. globosum inocula effectively reducing apple scab in growth chamber experiments was approximately 1 × 106 ascospores mL−1.

Evidence for the role of antibiosis in the antagonism of Chaetomium globosum to the apple scab pathogen, Venturia inaequalis

1984 ◽  
Vol 62 (9) ◽  
pp. 1819-1823 ◽  
Author(s):  
Daniel Cullen ◽  
John H. Andrews
Keyword(s):  
Antibiotic Production ◽  
Venturia Inaequalis ◽  
Apple Scab ◽  
Chaetomium Globosum ◽  
Growth Chamber ◽  
Fungistatic Activity ◽  
Chamber Studies ◽  
Growth Chamber Studies ◽  
Layer Chromatography

Ascospore suspensions and culture extracts of Chaetomium globosum Kunze: Fr. reduced infection of apple seedlings by Venturia inaequalis (Cke.) Wint. (anamorph, Spilocaea pomi Fr.) in growth-chamber studies. An agar diffusion assay was developed to assess the relative fungistatic activity of culture extracts of C. globosum. No differences were observed in the sensitivity of 37 V. inaequalis strains to C. globosum extracts. Seven strains of C. globosum from diverse habitats were evaluated for antibiotic production in culture. Significant differences in antibiotic production between strains were observed, and antibiotic levels were positively correlated with antagonism to V. inaequalis on seedlings in growth-chamber studies. The antibiotic chetomin was tentatively identified in culture extracts by thin-layer chromatography and ultraviolet absorbance. The selection of high antibiotic producing strains of C. globosum may significantly improve antagonistic performance in the field.

Benomyl-marked populations of Chaetomium globosum: survival on apple leaves with and without benomyl and antagonism to the apple scab pathogen, Venturia inaequalis

1985 ◽  
Vol 31 (3) ◽  
pp. 251-255 ◽  
Author(s):  
Daniel Cullen ◽  
John H. Andrews
Keyword(s):  
Resistant Strain ◽  
Venturia Inaequalis ◽  
Apple Scab ◽  
Chaetomium Globosum ◽  
Wild Type ◽  
Population Densities ◽  
Apple Trees ◽  
Initial Inoculum ◽  
Apple Leaves ◽  
Rate Of Decline

Resistance to the fungicide benomyl (BenR) was induced with N-methyl-N′-nitro-N-nitrosoguanidine in Chaetomium globosum isolated from apple leaves. The population densities of a resistant strain reintroduced to leaves on apple trees in an orchard were determined at 3 h, and 1 and 3 weeks following inoculation. Relative to wild-type parents, BenR populations declined more rapidly on orchard trees, but the rate of decline was reduced by amending initial inoculum with 18.5 ppm benomyl. Survival of BenRC. globosum increased 40–58% relative to BenRC. globosum applied without benomyl. In growth chamber experiments with potted apple seedlings, the BenR strain was as antagonistic as were the wild-type parents to the scab pathogen, Venturia inaequalis. The marked strain alone did not significantly reduce scab infection on saplings in the field; however, when it was applied with benomyl, scab severity was significantly (P = 0.01) less than with benomyl alone.

scholarly journals Efficient Control of Apple Scab with Targeted Spray Applications

Agronomy ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 217 ◽  
Author(s):  
Michael Chatzidimopoulos ◽  
Fenia Lioliopoulou ◽  
Thomas Sotiropoulos ◽  
Evangelos Vellios
Keyword(s):  
Venturia Inaequalis ◽  
Meteorological Data ◽  
Disease Incidence ◽  
Apple Scab ◽  
Similar Efficacy ◽  
Critical Growth ◽  
Growth Stages ◽  
Trial Site ◽  
Growing Seasons ◽  
Chemical Groups

For two consecutive growing seasons (2017 and 2018), three different fungicide spray programs, each with five sprays from unrelated chemical groups, were evaluated for their effectiveness against apple scab (causal agent: Venturia inaequalis) in an experimental trial in Greece. The targeted application programs consisted of five sprays with protective and systemic fungicides from unrelated chemical groups, in alternation. The applications were started at the pink bud stage (a copper-based fungicide had previously been applied at the green bud stage) and completed at the second fruit fall to arrest the primary infections by ascospores. These five-spray programs were compared to the standard farmer practice (12 sprays per season), whereas untreated plots were used as controls. The timing of the applications was based: a) on the critical growth stage of the crop, and b) on the risk analysis for infection calculated by the software Field Climate, which incorporated meteorological data from the trial site. All the five-spray programs were of very high efficacy against apple scab, showing disease severity ratings on leaves and fruits below 1.88%. In both years, in the untreated control, the disease incidence and severity on leaves ranged from 96.5% to 99.3% and from 65.2% to 75.93%, respectively. The five-spray programs showed similar efficacy to the standard 12-application program in all cases. From the results, it becomes apparent that apple scab can be controlled effectively by five targeted applications with selected fungicides at critical growth stages of the crop.

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.

scholarly journals Effect of Timing of Application of the Biological Control Agent Microsphaeropsis ochracea on the Production and Ejection Pattern of Ascospores by Venturia inaequalis

2004 ◽  
Vol 94 (12) ◽  
pp. 1305-1314 ◽  
Author(s):  
O. Carisse ◽  
D. Rolland
Keyword(s):  
Biological Control ◽  
Biological Control Agent ◽  
Venturia Inaequalis ◽  
Apple Scab ◽  
Control Agent ◽  
Sterile Leaf ◽  
Ascospore Production ◽  
Fall Application ◽  
Leaf Disks

Field and in vitro trials were conducted to establish the influence of the biological control agent Microsphaeropsis ochracea on the ejection pattern of ascospores by Venturia inaequalis and on apple scab development, and to establish the best timing of application. The ejection pattern of ascospores was similar on leaves sprayed with M. ochracea and on untreated leaves. Fall application of M. ochracea combined with a delayed-fungicide program was evaluated in orchards with intermediate and high scab risk. For both orchards, it was possible to delay the first three and two infection periods in 1998 and 1999, respectively, without causing significant increase or unacceptable leaf and fruit scab incidence. To evaluate the best timing of application, sterile leaf disks were inoculated with V. inaequalis and then with M. ochracea 0, 2, 4, 6, 8, 10, 12, 14, and 16 weeks later. After incubation under optimal conditions for pseudothecia development, the number of ascospores was counted. Similarly, M. ochracea was sprayed on scabbed leaves on seven occasions from August to November 1999 and 2000. Leaves were overwintered on the orchard floor and ascospore production was evaluated the following spring. Ascospore production was reduced by 97 to 100% on leaf disks inoculated with M. ochracea less than 6 weeks after inoculation with V. inaequalis, but ascospore production increased with increasing period of time when M. ochracea was applied 8 to 16 weeks after the inoculation with V. inaequalis. In the orchard, the greatest reduction in production of ascospores (94 to 96% in 2000 and 99% in 2001) occurred on leaves sprayed with M. ochracea in August. The production of ascospores was reduced by 61 to 84% in 2000 and 93% in 2001 on leaves sprayed with M. ochracea in September, reduced by 64 to 86% in 2000 and 74 to 89% in 2001 on leaves sprayed in October, and reduced by 54 and 67% in 2000 and 2001, respectively, on leaves sprayed in November. It was concluded that M. ochracea should be applied in August or September and that ascospore maturation models and delayed-fungicide program could be used in orchards treated with this biological control agent.

scholarly journals A genetic linkage map of Venturia inaequalis, the causal agent of apple scab

2009 ◽  
Vol 2 (1) ◽  
pp. 163 ◽  
Author(s):  
Xiangming Xu ◽  
Tony Roberts ◽  
Dez Barbara ◽  
Nick G Harvey ◽  
Liqiang Gao ◽  
...  
Keyword(s):  
Linkage Map ◽  
Genetic Linkage ◽  
Genetic Linkage Map ◽  
Venturia Inaequalis ◽  
Apple Scab ◽  
Causal Agent
Sign in / Sign up

Export Citation Format

Share Document