scholarly journals Application of fungicides during leaf fall to control apple scab (Venturia inaequalis) in the following season

2008 ◽  
Vol 61 ◽  
pp. 59-64 ◽  
Author(s):  
R.M. Beresford ◽  
P.N. Wood ◽  
P.W. Shaw ◽  
T.J. Taylor
Keyword(s):  
Fungicide Resistance ◽  
Venturia Inaequalis ◽  
Apple Scab ◽  
Fruit Production ◽  
Leaf Fall ◽  
Apple Orchards ◽  
Resistance Risk ◽  
Chemical Residues ◽  
Integrated Fruit Production

Leaf fall applications of fungicides to reduce scab in apple orchards were investigated to reduce reliance on summer fungicides that can cause trace chemical residues on harvested fruit Two applications of fungicides including captan tolyfluanid myclobutanil and urea were made at 1020 and 5060 leaf fall in four orchard trials in Nelson and Hawkes Bay using the cultivars Royal Gala Braeburn Fuji and Sciros/Pacific Rosetrade; Trial orchards received standard spring and summer fungicide programmes that complied with Integrated Fruit Production and were monitored for leaf and fruit scab in December and at harvest Significant reductions in leaf or fruit scab occurred in three out of five comparisons involving different sites years and cultivars suggesting that autumn applications can reduce scab in the following season Captan and tolyfluanid appeared most useful for autumn application Myclobutanil should not be used because of the fungicide resistance risk Results with urea were variable

Resistance to Myclobutanil in Populations of Venturia inaequalis in Winchester, Virginia

2007 ◽  
Vol 8 (1) ◽  
pp. 3 ◽  
Author(s):  
Sasha C. Marine ◽  
David G. Schmale ◽  
Keith S. Yoder
Keyword(s):  
Fungicide Resistance ◽  
Venturia Inaequalis ◽  
Apple Scab ◽  
Apple Orchards ◽  
The Mean ◽  
Moderately Resistant

Sterol-inhibiting (SI) fungicides are widely used to manage apple scab, caused by Venturia inaequalis. However, recent observations indicate that populations of V. inaequalis in orchards in Virginia have developed resistance to myclobutanil and other SI fungicides. Little is known about the frequency and distribution of fungicide resistance in apple scab populations in Virginia. Isolates of V. inaequalis were collected from three different apple orchards in Winchester, VA in 2006. Orchards were treated with myclobutanil on 12 April, 19 April, 1 May, 30 May, and 7 July. The sensitivity of 87 single-spored isolates of V. inaequalis to myclobutanil was determined by monitoring their growth on agar dishes amended with 0, 0.1, 0.5, or 1.0 μg/ml myclobutanil. A relative continuum of fungicide resistance was observed: 16 isolates were resistant, 40 isolates were moderately resistant, and 31 isolates were sensitive to myclobutanil. After 28 days, the mean growth of isolates collected from trees treated with myclobutanil was significantly greater than that of isolates collected from non-treated trees at all concentrations of myclobutanil tested in vitro. High levels of fungicide resistance found in populations of V. inaequalis suggest that replacement programs may need to be developed to manage apple scab in Virginia. Accepted for publication 4 September 2007. Published 13 November 2007.

scholarly journals Sensitivity of Venturia inaequalis to myclobutanil penconazole and dodine in relation to fungicide use in Hawkes Bay apple orchards

2012 ◽  
Vol 65 ◽  
pp. 106-113
Author(s):  
R.M. Beresford ◽  
P.J. Wright ◽  
P.N. Wood ◽  
N.M. Park
Keyword(s):  
Venturia Inaequalis ◽  
Resistance Management ◽  
Black Spot ◽  
High Sensitivity ◽  
Fruit Production ◽  
Apple Orchards ◽  
Management Guidelines ◽  
Dmi Fungicides ◽  
Integrated Fruit Production ◽  
Demethylation Inhibitor

A survey of Integrated Fruit Production and organic apple orchards in Hawkes Bay in 201011 investigated sensitivity of Venturia inaequalis isolates to demethylation inhibitor (DMI) and dodine fungicides EC50 values from mycelial growth assays for two DMIs showed continued loss of sensitivity since the 1990s Sensitivity was lower in orchards where DMI usage exceeded resistance management guidelines The most DMIsensitive isolates were found in one organic orchard Plant inoculations showed that black spot control of myclobutanilresistant V inaequalis strains by one application of myclobutanil was only 55 compared with 99 for myclobutanilsensitive strains The study suggests that resistance to DMI fungicides has continued to develop that loss of black spot control could be expected in some orchards and that DMI resistance management guidelines need reviewing There was high sensitivity to dodine in all orchards (mean EC50 of 024 mg/litre) and no evidence of increased resistance since the 1990s

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.

scholarly journals Evidence for the Predisposition of Fungicide-Resistant Isolates of Venturia inaequalis to a Preferential Selection for Resistance to Other Fungicides

2001 ◽  
Vol 91 (8) ◽  
pp. 776-781 ◽  
Author(s):  
Wolfram Köller ◽  
W. F. Wilcox
Keyword(s):  
Fungicide Resistance ◽  
Venturia Inaequalis ◽  
Apple Scab ◽  
The United States ◽  
Cross Resistance ◽  
Resistance Development ◽  
Flexible Response ◽  
Sterol Demethylation Inhibitors ◽  
Selection For ◽  
Selection Of

In the United States, populations of the apple scab pathogen Venturia inaequalis have progressed through three consecutive rounds of fungicide resistance development, first to dodine, then to the benzimidazoles, and most recently to the sterol demethylation inhibitors (DMIs). Analysis of extensive monitoring data have to date provided no indication of detectable cross-resistance or partial cross-resistance of V. inaequalis populations to the three unrelated classes of fungicides prior to the selection of resistant subpopulations. However, in this study, resistance to both benomyl and DMIs developed to significantly higher frequencies within the previously established dodine-resistant population than in the population sensitive to dodine. Accelerated selection of phenotypes double resistant to dodine and the DMI fenarimol was apparent over the course of distinct seasons of apple scab management with either dodine or fenarimol. The data provide evidence for an accelerated speed of resistance development among phenotypes of V. inaequalis already resistant to an unrelated fungicide. This finding represents a departure from the previous model, which assumed entirely independent rounds of resistance developments. The data indicate that phenotypes of V. inaequalis might not only be selected for the trait of fungicide resistance but also for traits allowing a more flexible response to changes in the environment where they compete.

scholarly journals Identification of Resistance to Multiple Fungicides in Field Populations of Venturia inaequalis

Plant Disease ◽  
2011 ◽  
Vol 95 (8) ◽  
pp. 921-926 ◽  
Author(s):  
Kimberly S. Chapman ◽  
George W. Sundin ◽  
Janna L. Beckerman
Keyword(s):  
Fungicide Resistance ◽  
Mycelial Growth ◽  
Venturia Inaequalis ◽  
Apple Scab ◽  
Field Resistance ◽  
Single Spore ◽  
Mycelium Growth ◽  
Thiophanate Methyl ◽  
Development Of Resistance

Venturia inaequalis, the causal agent of apple scab, is controlled primarily by fungicides. Long-term, extensive fungicide use has led to the development of resistance to multiple fungicides. To assess fungicide resistance, isolates of V. inaequalis were collected from Indiana and Michigan orchards. Single-spore derived isolates were evaluated by mycelium growth assays with previously determined discriminatory doses on media containing dodine, kresoxim-methyl, myclobutanil, or thiophanate-methyl. Of 195 isolates tested, 5.2, 0.7, 57.0, and 92.6% of isolates were found to be resistant to dodine, kresoxim-methyl, myclobutanil, and thiophanate-methyl, respectively. This is the first report of kresoxim-methyl field resistance in these states. Isolates resistant or shifted to a single fungicide were often found to have multiple fungicide resistance. Of all isolates tested, 38% were identified as resistant or shifted to two fungicides, and 12% were resistant or shifted to all four fungicides tested. No fitness penalty was found for isolates resistant to multiple fungicides based on a statistical analysis of mycelial growth and conidial production.

scholarly journals First Report of QoI Resistance in Venturia inaequalis Causing Apple Scab in Apple Orchards in Turkey

Plant Disease ◽  
2016 ◽  
Vol 100 (5) ◽  
pp. 1016-1016 ◽  
Author(s):  
C. Turan ◽  
I. M. Nanni ◽  
N. Tosun ◽  
M. Collina
Keyword(s):  
Venturia Inaequalis ◽  
Apple Scab ◽  
Apple Orchards ◽  
First Report ◽  
Qoi Resistance

scholarly journals Improving the management of mealybugs (Pseudococcidae) in apple orchards

2012 ◽  
Vol 65 ◽  
pp. 44-48
Author(s):  
P.L. Lo ◽  
J.T.S. Walker ◽  
T.M. Fraser ◽  
D.W. Manktelow
Keyword(s):  
New Zealand ◽  
Best Practice ◽  
Fruit Production ◽  
Apple Orchards ◽  
Key Factors ◽  
Time Of Application ◽  
The Mean ◽  
Integrated Fruit Production ◽  
Insecticide Sprays

Mealybug infestations in New Zealand apples declined when integrated fruit production was implemented in the late 1990s In Hawkes Bay however mealybugs have recently become an increasing problem The mean incidence of mealybugs at harvest increased from 17 in 2008 to 22 in 2010 In 2009 and 2010 almost 50 of blocks had a higher incidence than the previous year Analysis of spray diaries suggested that spray programmes up to 200910 were inadequate to maintain longterm suppression of mealybugs Key factors were the number of insecticide sprays their time of application and the choice of product but not spray coverage Consequently in spring 2010 orchard managers were encouraged to follow a best practice spray programme against mealybugs which led to markedly improved mealybug control At harvest in 2011 the mean incidence was 07 and just 14 of blocks had more mealybugs than the previous year while almost 60 had fewer

scholarly journals Managing Resistance of Venturia inaequalis to the Strobilurin Fungicides

2004 ◽  
Vol 5 (1) ◽  
pp. 3 ◽  
Author(s):  
William W. Turechek ◽  
Wolfram Köller
Keyword(s):  
Fungicide Resistance ◽  
Large Scale ◽  
Venturia Inaequalis ◽  
Apple Scab ◽  
Resistance Management ◽  
Management Program ◽  
Crop Losses ◽  
The Past ◽  
Strobilurin Fungicides ◽  
Low Rate

Over the past thirty years, fungicide resistance has been cited as the cause of large-scale crop losses due to apple scab in a number of commercial orchards in the Northeast. The strobilurins represent the most recent class of fungicides for which the threat of resistance exists. In this article we examine the use of strobilurin fungicides at their highest and lowest labeled rates and as a mixture of the lowest labeled rate with a protectant fungicide in commercial spray programs for efficacy against apple scab as well as their utility in a resistance management program. Our results suggest that anti-resistance properties of high strobilurin rates are superior to low rates and low rate mixtures with a protectant fungicide. Accepted for publication 26 August 2004. Published 8 September 2004.

scholarly journals Эффективность биостимулятора Реглалг для защиты яблони от парши (Venturia Inaequalis Wint.)

2020 ◽  
Author(s):  
Иван Боубэтрын ◽  
◽  
Алехандру Даскaлюк ◽  
Keyword(s):  
Economic Efficiency ◽  
Negative Impact ◽  
Plant Protection ◽  
Venturia Inaequalis ◽  
Apple Scab ◽  
Plant Protection Products ◽  
Combined Effect ◽  
Apple Orchards ◽  
The Cost

The scope of the research was to determine the efficiency of the combined effect of fungicides and the biostimulator Reglalag in the protection of apple orchards from apple scab disease. The introduction of a biostimulator into the tank mixture with fungicides allowed us to reduce by half the quantity of synthetic plant protection products. This combination allows us to reduce the cost of plant protection, reduces the negative impact of the fungicides on environment, and increases the economic efficiency of apple cultivation.

Sign in / Sign up

Export Citation Format

Share Document