No Evidence of QoI Resistance in Apple Powdery Mildew (Podosphaera leucotricha)

2014 ◽  
Vol 163 (3) ◽  
pp. 178-184 ◽  
Author(s):  
Andreas Koch ◽  
Friedrich Felsenstein ◽  
Gerd Stammler
Keyword(s):  
Powdery Mildew ◽  
Podosphaera Leucotricha ◽  
Qoi Resistance

scholarly journals Fitness of Erysiphe necator with G143A-Based Resistance to Quinone Outside Inhibitors

Plant Disease ◽  
2014 ◽  
Vol 98 (11) ◽  
pp. 1494-1502 ◽  
Author(s):  
Lynn Esther E. Rallos ◽  
Nels G. Johnson ◽  
David G. Schmale ◽  
Aaron J. Prussin ◽  
Anton B. Baudoin
Keyword(s):  
Powdery Mildew ◽  
Quantitative Polymerase Chain Reaction ◽  
Field Trials ◽  
Resistance Development ◽  
Erysiphe Necator ◽  
Potted Plants ◽  
Sterol Demethylation Inhibitors ◽  
Quinone Outside Inhibitors ◽  
Competition Assays ◽  
Qoi Resistance

Management of grape powdery mildew (Erysiphe necator) using quinone outside inhibitors (QoIs) has eroded in an increasing number of regions due to resistance development. To determine persistence of resistance when QoIs are withdrawn, competition assays were conducted on unsprayed grape plants (Vitis vinifera ‘Chardonnay’) by cycling mixtures of resistant and sensitive isolates characterized as genetically diverse based on microsatellite analyses. Under laboratory conditions, %G143A, quantified by quantitative polymerase chain reaction (qPCR), increased significantly, indicating competitiveness of the resistant fraction. To confirm competitiveness in the field, trials using potted plants were conducted. Percent G143A tended to decrease in one growing season, probably due to spore migration and mixing of populations with natural background inoculum. In a second season, QoI resistance persisted at high frequency for 4 weeks. Resistant populations were also found to persist in one vineyard without QoI application for four consecutive years. The frequency was still about 25% in the fourth year, with higher frequency (36%) in a hotspot section. QoI-resistant populations with >5% G143A also harbored Y136F in the cyp51 gene that confers some resistance to sterol demethylation inhibitors, another fungicide class for powdery mildew control. Double resistance could have been partly responsible for persistence of QoI resistance at this location.

Podosphaera leucotricha. [Descriptions of Fungi and Bacteria].

1967 ◽  
Author(s):  
J. N. Kapoor
Keyword(s):  
South Africa ◽  
New Zealand ◽  
North America ◽  
Powdery Mildew ◽  
South America ◽  
Geographical Distribution ◽  
Prunus Persica ◽  
Podosphaera Leucotricha

Abstract A description is provided for Podosphaera leucotricha. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: On Malus spp., chiefly on M. pumila (apple), peach (Prunus persica), quince (Cydonia ualgaris) and Photinia spp. also attacked (Hirata, 1966). Also reported on almond fruit (43, 2544). DISEASE: Powdery mildew of apple. GEOGRAPHICAL DISTRIBUTION: Africa (? Kenya, Rhodaia, South Africa, Tanzania); Asia (China, India, Israel, Japan, U.S.S.R.); Australia and New Zealand, Europe (widely distributed) North America (Canada and U.S.A.); South America (Argentina, Brazil, Chile, Colombia, Peru). (CMI map 118). TRANSMISSION: Overwinters on host as dormant mycdium in blossom buds. The role of deistothecia in overwintering is doubtful. Spread by wind-borne conidia (Anderson, 1956).

scholarly journals Pre-selection of apple seedlings for partial powdery mildew (Podosphaera leucotricha Ell. et Ev. /Salm./) resistance

2011 ◽  
Vol 50 (No. 2) ◽  
pp. 65-69 ◽  
Author(s):  
J. Blažek
Keyword(s):  
Powdery Mildew ◽  
First Year ◽  
Podosphaera Leucotricha ◽  
Green House ◽  
Healthy State ◽  
The Mean ◽  
Resistant Genotypes ◽  
Different Levels ◽  
Final Selection ◽  
Selection Of

Incidences of powdery mildew were repeatedly evaluated for two years on 1 420 young seedlings of 20 progenies (of different levels of mildew susceptibility) in a green house, and then for 10 years on 642 seedlings in an orchard. Part of the seedlings in the orchard were pre-selected for the characteristic and others not. Except for the first scoring done in the first year, there was no correlation between mildew incidence on individual seedlings in the green house and their mean performance in the orchard. The seedlings with scores above 6 (resistant or tolerant) at the first stage of evaluation in the green house, however, yielded four times more desirable seedlings after final selection in the orchard than the mean of the total. The progenies that had a better healthy state as a whole yielded more partially resistant genotypes than those with low mean scores. Therefore, the progenies that most rapidly develop infestation on the whole lot should be discarded, whereas those that retain a healthy state longer should be subjected to individual selection according to the previous item.

scholarly journals Apple powdery mildew caused by Podosphaera leucotricha: some important features of biology and epidemiology

2009 ◽  
Vol 15 (1-2) ◽  
Author(s):  
I. J. Holb
Keyword(s):  
Powdery Mildew ◽  
Temporal Dynamics ◽  
Host Susceptibility ◽  
Spore Dispersal ◽  
Podosphaera Leucotricha ◽  
Causal Organism ◽  
Disease Symptoms ◽  
Diurnal Patterns ◽  
Basic Features ◽  
Durability Of Resistance

In this review, some important features of biology and epidemiology are summarised for apple powdery mildew (Podosphaera leucotricha). In the first part of the review, the geographical distribution or the pathogen are discussed, then the morphology and taxonomy of the causal organism are described. Disease symptoms or apple powdery mildew are also shown and then host susceptibility/resistance is discussed in relation to durability of resistance. In the second part of this review, the general disease cycle of powdery mildew on apple are demonstrated and some basic features of powdery mildew epidemiology (such response of the pathogen to temperature, relative humidity, and rain as well as spore production, spore dispersal, diurnal patterns and temporal dynamics of the pathogen/disease) are also given on apple host.

scholarly journals Strobilurin (QoI) Resistance in Populations of Erysiphe necator on Grapes in Michigan

Plant Disease ◽  
2012 ◽  
Vol 96 (11) ◽  
pp. 1621-1628 ◽  
Author(s):  
L. A. Miles ◽  
T. D. Miles ◽  
W. W. Kirk ◽  
A. M. C. Schilder
Keyword(s):  
Powdery Mildew ◽  
Fungicide Resistance ◽  
Resistance Management ◽  
The United States ◽  
Suboptimal Control ◽  
Single Nucleotide ◽  
Erysiphe Necator ◽  
Nucleotide Mutation ◽  
Conidium Germination ◽  
Qoi Resistance

Powdery mildew, caused by Erysiphe necator, is the most common and destructive disease of grapes (Vitis spp.) worldwide. In Michigan, it is primarily controlled with fungicides, including strobilurins (quinone outside inhibitors [QoIs]). Within the United States, resistance to this class of fungicides has been reported in E. necator populations in some east coast states. Among 12 E. necator isolates collected from five Michigan vineyards in 2008, one carried the G143A single-nucleotide mutation responsible for QoI resistance. This isolate was confirmed to be resistant in a conidium germination assay on water agar amended with trifloxystrobin at 0.001, 0.01, 0.1, 1, 10, or 100 μg/ml and salicylhydroxamic acid (100 mg/liter). The mutant isolate was able to germinate on media amended with 100 μg/ml trifloxystrobin, whereas a representative wild-type isolate did not germinate at concentrations higher than 0.1 μg/ml. In 2009, 172 isolates were collected from a total of 21 vineyards (juice and wine grapes): three vineyards with no fungicide application history (baseline sites), six research vineyards, and 12 commercial vineyards. QoI resistance was defined as the effective concentration that inhibited 50% of conidial germination (EC50) > 1 μg/ml. Isolates from baseline sites had EC50 values mostly below 0.01 μg/ml, while isolates that were highly resistant to trifloxystrobin (EC50 > 100 μg/ml) occurred in five research and three commercial wine grape vineyards at frequencies of 40 to 100% and 25 to 75% of the isolates, respectively. The G143A mutation was detected in every isolate with an EC50 > 1 μg/ml. These results suggest that fungicide resistance may play a role in suboptimal control of powdery mildew observed in some Michigan vineyards and emphasizes the need for continued fungicide resistance management.

Eradication of apple powdery mildew (Podosphaera leucotricha) with dormant-season sprays of surface-active agents

1978 ◽  
Vol 9 (1) ◽  
pp. 12-21 ◽  
Author(s):  
Eric C. Hislop ◽  
Derek R. Clifford ◽  
Margaret E. Holgate ◽  
Peter Gendle
Keyword(s):  
Powdery Mildew ◽  
Podosphaera Leucotricha ◽  
Surface Active Agents ◽  
Dormant Season ◽  
Surface Active

scholarly journals Apple powdery mildew caused by Podosphaera leucotricha: some aspects of disease management

2014 ◽  
Vol 20 (1-2) ◽  
Author(s):  
I. J. Holb
Keyword(s):  
Biological Control ◽  
Disease Management ◽  
Powdery Mildew ◽  
Chemical Control ◽  
Apple Cultivar ◽  
Apple Orchards ◽  
Cultivar Resistance ◽  
Podosphaera Leucotricha ◽  
Control Options ◽  
Apple Cultivars

Apple powdery mildew (Podoshphaera leucorticha) occurs wherever apples are grown. One of the most important fungal disease of apple which causing severe econimic loss on susceptible apple cultivars. This review focuses on the control of apple powdery mildew. The first part of the study provides details of novel aspects of non-chemical control approaches, including agronomic measures, mechanical and biological control options as well as essential features of apple cultivar resistance. After this, developments in chemical control options are described sperately for integrated and organic apple orchards.

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