The suppression of ascospore production to facilitate the control of apple scab (Venturia inaequalis (Cke.) Wint.)

1965 ◽  
Vol 56 (2) ◽  
pp. 285-292 ◽  
Author(s):  
R. T. BURCHILL ◽  
K. E. HUTTON
Keyword(s):  
Venturia Inaequalis ◽  
Apple Scab ◽  
Ascospore Production

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 Comparative Studies on the Effect of Adjuvants with Urea to Reduce the Overwintering Inoculum of Venturia inaequalis

Plant Disease ◽  
2019 ◽  
Vol 103 (3) ◽  
pp. 531-537 ◽  
Author(s):  
Janna Beckerman ◽  
Chelsi Abbott
Keyword(s):  
Leaf Litter ◽  
Litter Decomposition ◽  
Comparative Studies ◽  
Venturia Inaequalis ◽  
Apple Scab ◽  
Organic Surfactant ◽  
Comparable Performance ◽  
Improved Sanitation ◽  
Litter Degradation ◽  
Ascospore Production

A 2-year study on the use of organic and conventional adjuvants alone, or mixed with urea, was conducted for management of overwintering inoculum of the apple scab pathogen, Venturia inaequalis. Select adjuvants (LI 700, Bond Max, Latron B-1956, and Organic Wet Betty [OWB]) have the potential to hasten urea-driven leaf litter decomposition and reduce V. inaequalis overwintering inoculum comparable to urea, and that one organic surfactant could perform the same level of leaf decomposition as urea. Combinations of adjuvants with urea significantly improved leaf litter degradation compared with urea alone, concomitant with reducing the number of pseudothecia present and pseudothecium fertility. We demonstrate that the combination of urea with Bond Max or OWB reduced pseudothecia fertility and ascospore production to less than 5% in the remaining pseudothecia, a significantly greater reduction than with urea alone. These results suggest that conventional growers combine urea with Bond Max or OWB to more effectively reduce overwintering inoculum, and that the adjuvant OWB can provide organic growers with comparable performance to urea used in conventional orchards for improved sanitation.

EFFECTS OF SEASONAL FUNGICIDE SPRAYS ON PERITHECIUM FORMATION AND ASCOSPORE PRODUCTION IN VENTURIA INAEQUALIS

1975 ◽  
Vol 55 (3) ◽  
pp. 737-742 ◽  
Author(s):  
R. G. ROSS ◽  
R. J. NEWBERY
Keyword(s):  
Venturia Inaequalis ◽  
Apple Scab ◽  
Malus Pumila ◽  
In Vitro Production ◽  
Ascospore Discharge ◽  
Malus Pumila Mill ◽  
Terminal Shoot ◽  
Vitro Production ◽  
Ascospore Production

Seasonal sprays of the systemic fungicides benomyl, thiophanate-methyl, Bay Dam 18654 and Bavistin applied for the control of apple scab, Venturia inaequalis (Cke.) Wint., either completely or almost completely suppressed the production of ascospores in apple (Malus pumila Mill.) leaves overwintered in the orchard. In vitro production of perithecia on leaves sterilized with propylene oxide was also inhibited by these sprays, although some treatments suppressed ascospore discharge in overwintered leaves that failed to inhibit perithecium formation on the sterile leaves. Ascospore production was also reduced in leaves from spur clusters that had been sprayed with Dikar and metiram. In terminal shoot leaves from Dikar-sprayed trees, ascospore production was higher in leaves collected from near the tip than in leaves collected from near the base of the terminal growth.

scholarly journals Role of urea in the reduction of apple primary infections by Venturia inaequalis (Cooke) Aderh

2013 ◽  
Vol 55 (1) ◽  
pp. 225-231
Author(s):  
Beata Meszka ◽  
Anna Bielenin
Keyword(s):  
Chemical Control ◽  
Primary Infection ◽  
Venturia Inaequalis ◽  
Apple Scab ◽  
Leaf Fall ◽  
Urea Treatment ◽  
Apple Leaves ◽  
Leaf Infection ◽  
Ascospore Production

The effect of pre-leaf fall of 5% urea treatment on primary infection of apple by <i>Venturia inaequalis</i>, the cause of scab, was investigated in commercial apple orchards of McIntosh cv. in different regions of Poland, at Miłobądz, Sinołęka and Dąbrowice. Additionally, the development of pseudothecia and maturation of ascospores were evaluated in the spring on apple leaves of two cultivars (McIntosh and Gloster) treated with 5% solution of urea. Microscopic observations of leaves showed that urea treatment significantly reduced the number of pseudothecia (by ca. 90%) and ascospore production. Low number of ascospores after urea treatment has strongly affected primary infection of apple by the fungus in all tested orchards. Reduction of leaf infection on control trees was usually more than 30%. Also efficacy of chemical control of apple scab was significantly higher on plots treated with urea.

scholarly journals Suppression of Venturia inaequalis (apple scab) ascospore production using autumnapplied fungicides

2008 ◽  
Vol 61 ◽  
pp. 54-58
Author(s):  
P.N. Wood ◽  
R.M. Beresford ◽  
T.J. Taylor
Keyword(s):  
Fungicide Resistance ◽  
Venturia Inaequalis ◽  
Apple Scab ◽  
Black Spot ◽  
Field Application ◽  
Copper Hydroxide ◽  
Apple Leaves ◽  
Application Rates ◽  
Resistant Strains ◽  
Ascospore Production

In autumn 2006 apple leaves with visible scab (black spot) symptoms were collected at the time of leaf fall and dipped in fungicides at concentrations equivalent to field application rates The leaves were overwintered on gravel and ascospore production measured on three dates during the following spring using suction spore traps Of ten fungicides tested myclobutanil trifloxystrobin captan dodine tolyfluanid and cyprodinil either reduced or delayed ascospore production by Venturia inaequalis during the following spring compared with a waterdipped control Metiram dithianon urea and copper hydroxide had a minimal effect on ascospore production Leaves from a separate orchard trial produced significantly fewer ascospores after myclobutanil treatment than after captan treatment Captan and tolyfluanid are recommended for autumn application to control scab because they significantly reduced or delayed ascospore production and have a low risk of selecting resistant strains of V inaequalis Although also effective myclobutanil trifloxystrobin dodine and cyprodinil should not be used for autumn application because of the risk of fungicide resistance

scholarly journals Effect of Fall Application of Fungal Antagonists on Spring Ascospore Production of the Apple Scab Pathogen, Venturia inaequalis

2000 ◽  
Vol 90 (1) ◽  
pp. 31-37 ◽  
Author(s):  
Odile Carisse ◽  
Vincent Philion ◽  
Daniel Rolland ◽  
Julie Bernier
Keyword(s):  
Large Scale ◽  
Venturia Inaequalis ◽  
Apple Scab ◽  
Leaf Fall ◽  
Natural Conditions ◽  
Fungal Isolates ◽  
Trichoderma Sp ◽  
Ascospore Production ◽  
Fall Application ◽  
Leaf Disks

The influences of Microsphaeropsis sp., M. arundinis, Ophiostoma sp., Diplodia sp., and Trichoderma sp., all antagonists of Venturia inaequalis, on ascospore production were evaluated under natural conditions and compared with urea and Athelia bombacina, a known antagonist. In the autumn, the fungi were applied to leaf disks artificially inoculated with V. inaequalis and to scabbed apple (Malus domestica) leaves incubated under controlled and natural conditions. In addition, large-scale trials were conducted with Microsphaeropsis sp. applied either as a foliar postharvest spray or as a ground application at 90% leaf fall. All fungal isolates, except Ophiostoma sp., were recovered from the leaf material that overwintered in the orchard. All treatments, except those with Ophiostoma sp., resulted in a significant reduction in V. inaequalis ascospore production on the leaf disks incubated under controlled conditions or in the orchard. In 1997, leaves with apple scab lesions treated with urea or Microsphaeropsis sp. produced significantly fewer ascospores of V. inaequalis than did nontreated leaves, with a reduction of 73.0 and 76.3%, respectively. In 1998, leaves treated with Microsphaeropsis sp., urea, Trichoderma sp., A. bombacina, and M. arundinis reduced ascospore production by 84.3, 96.6, 75.2, 96.6, and 52.2%, respectively. Based on all tests combined, the most efficient isolate was Microsphaeropsis sp. Postharvest applications of Microsphaeropsis sp. reduced the total amount of airborne ascospores trapped by 70.7 and 79.8% as compared with the nontreated plots in 1997 and 1998, respectively. Microsphaeropsis sp. provided a significant and consistent reduction in ascospore production in all tests.

scholarly journals Full-season and post-harvest applications of sterol-inhibiting fungicides to reduce ascospore formation in Venturia inaequalis

2005 ◽  
Vol 71 (1) ◽  
pp. 9-15 ◽  
Author(s):  
A.R. Biggs ◽  
J. Warner
Keyword(s):  
Venturia Inaequalis ◽  
Apple Scab ◽  
Post Harvest ◽  
Highly Effective ◽  
Causal Fungus ◽  
Ascospore Production ◽  
Ascospore Formation ◽  
Better Than

Several sterol-inhibiting (SI) fungicides were tested in post-harvest and full-season spray programs for the inhibition of ascospore formation by Venturia inaequalis, the causal fungus of apple scab. Post-harvest treatments with flusilazole and diniconazole were comparable to or better than those with benomyl and suppressed ascospore production by 55 to 90 %, although bitertanol stimulated ascospore production by up to 52 %. When applied nine times in full-season programs, bitertanol, flusilazole, and triflumizole reduced ascospore formation to a degree similar to or greater than that achieved with dodine. Full-season programs with SI fungicides in combination with mancozeb were highly effective for reducing ascospore production.

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.

Sign in / Sign up

Export Citation Format

Share Document