Abstract
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.
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Claims 5
Claim · model-written summary
Of 87 V. inaequalis isolates from apple orchards, 16 isolates were resistant to myclobutanil.
- Taxon
- apple
Malus domesticae2 - Interactor
- V. inaequalis
Venturia inaequalise2pathogen - Outcome
- isolates were resistante1
- Value
- 16 isolatese1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“A relative continuum of fungicide resistance was observed: 16 isolates were resistant, 40 isolates were moderately resistant, and 31 isolates were sensitive to myclobutanil”
e2“Isolates of V. inaequalis were collected from three different apple orchards in Winchester, VA in 2006”
Claim · model-written summary
Of 87 V. inaequalis isolates from apple orchards, 40 isolates were moderately resistant to myclobutanil.
- Taxon
- appleMalus domesticae2
- Interactor
- V. inaequalisVenturia inaequalise2pathogen
- Outcome
- isolates were moderately resistante1
- Value
- 40 isolatese1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“A relative continuum of fungicide resistance was observed: 16 isolates were resistant, 40 isolates were moderately resistant, and 31 isolates were sensitive to myclobutanil”
e2“Isolates of V. inaequalis were collected from three different apple orchards in Winchester, VA in 2006”
Claim · model-written summary
Of 87 V. inaequalis isolates from apple orchards, 31 isolates were sensitive to myclobutanil.
- Taxon
- appleMalus domesticae2
- Interactor
- V. inaequalisVenturia inaequalise2pathogen
- Outcome
- isolates were sensitivee1
- Value
- 31 isolatese1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“A relative continuum of fungicide resistance was observed: 16 isolates were resistant, 40 isolates were moderately resistant, and 31 isolates were sensitive to myclobutanil”
e2“Isolates of V. inaequalis were collected from three different apple orchards in Winchester, VA in 2006”
Claim · model-written summary
Isolates from myclobutanil-treated trees grew significantly more than isolates from non-treated trees at all in vitro myclobutanil concentrations.
- Taxon
- appleMalus domesticae2
- Treatment
- trees treated with myclobutanile3
- Interactor
- V. inaequalisVenturia inaequalise2pathogen
- Outcome
- mean growth of isolatese3
- Direction
- significantly greatere3
- Comparator
- non-treated treese3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e2“Isolates of V. inaequalis were collected from three different apple orchards in Winchester, VA in 2006”
e3“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”
Claim · model-written summary
Replacement fungicide programs may need to be developed to manage apple scab in Virginia.
- Taxon
- appleMalus domesticae4
- Outcome
- replacement programse4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e4“replacement programs may need to be developed to manage apple scab in Virginia”
The same questions in other papers
myclobutanil · Venturia inaequalis · Malus domestica (apple)Positive and negative results
3 papers in the same direction as this paper · 3 in the opposite direction
- positive
- positive
- positive
3 papers more in this group
See all 7 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.