Abstract
Anthracnose crown rot of strawberry, caused by Colletotrichum acutatum, is an important disease affecting California nursery and fruit production. Preplant dip treatments of transplants with fludioxonil-cyprodinil or azoxystrobin are industry standards for managing the disease and have been used extensively. Following reports of reduced efficacy of azoxystrobin in the field, high levels of quinone outside inhibitor (QoI) resistance were detected in California isolates of the pathogen. Resistance was associated with the G143A mutation in the cytochrome b gene, similar to a previous report from Florida, and there were no detected fitness penalties in pathogenicity or virulence. Therefore, several alternative fungicides were investigated in laboratory and field studies. Subsequently, the new biofungicide natamycin was identified. Baseline sensitivities of 74 isolates of C. acutatum to natamycin were determined to be unimodal, with a range from 0.526 to 1.996 μg/ml (mean 0.973 μg/ml). Although this toxicity was considerably lower than that of azoxystrobin (using sensitive isolates), fludioxonil, or cyprodinil, dip treatments of transplants with natamycin (at 500 or 1000 mg/liter) were highly effective. Disease severity and plant mortality in field studies with inoculated transplants were reduced to similarly low levels as treatments containing fludioxonil, whereas azoxystrobin failed in inoculations with QoI-resistant isolates of C. acutatum. Fruit yield was also significantly increased by natamycin as compared with the inoculated control. Differences in disease susceptibility were observed among cultivars evaluated, with Monterey and Portola more susceptible than Fronteras. Natamycin has a unique mode of action that is different from other fungicides registered on strawberry and, based on this research, was registered in the United States as a preplant, biofungicide dip treatment of strawberry transplants for management of anthracnose crown rot.
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Claims 8
Claim · model-written summary
Baseline sensitivity of 74 Colletotrichum acutatum isolates to natamycin was unimodal, ranging from 0.526 to 1.996 μg/ml (mean 0.973 μg/ml).
- Taxon
- strawberry
_single2.jpg?width=60)
Fragaria ×ananassae1 - Treatment
- natamycine2
- Interactor
- Colletotrichum acutatum
Colletotrichum acutatume1pathogen - Outcome
- Baseline sensitivitiese2
- Value
- 0.526 to 1.996 μg/ml (mean 0.973 μg/ml)e2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
_single2.jpg?width=500)
Verbatim
e1“Anthracnose crown rot of strawberry, caused by Colletotrichum acutatum”
e2“Baseline sensitivities of 74 isolates of C. acutatum to natamycin were determined to be unimodal, with a range from 0.526 to 1.996 μg/ml (mean 0.973 μg/ml)”
Claim · model-written summary
Natamycin dip treatments of transplants were highly effective and reduced disease severity and plant mortality in field studies to levels similar to fludioxonil treatments.
- Taxon
- strawberryFragaria ×ananassae1
- Treatment
- dip treatments of transplants with natamycine3
- Interactor
- Colletotrichum acutatumColletotrichum acutatume1pathogen
- Outcome
- Disease severity and plant mortalitye4
- Direction
- reducede4
- Comparator
- treatments containing fludioxonile4
- Setting
- field studiese4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Anthracnose crown rot of strawberry, caused by Colletotrichum acutatum”
e3“dip treatments of transplants with natamycin (at 500 or 1000 mg/liter) were highly effective”
e4“Disease severity and plant mortality in field studies with inoculated transplants were reduced to similarly low levels as treatments containing fludioxonil”
Claim · model-written summary
Azoxystrobin failed to control anthracnose crown rot in inoculations with QoI-resistant isolates.
- Taxon
- strawberryFragaria ×ananassae1
- Treatment
- azoxystrobine5
- Interactor
- C. acutatumColletotrichum acutatume5pathogen
- Outcome
- failed in inoculations with QoI-resistant isolatese5
- Direction
- failede5
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Anthracnose crown rot of strawberry, caused by Colletotrichum acutatum”
e5“azoxystrobin failed in inoculations with QoI-resistant isolates of C. acutatum”
Claim · model-written summary
Natamycin significantly increased fruit yield compared with the inoculated control.
- Taxon
- strawberryFragaria ×ananassae1
- Treatment
- natamycine6
- Outcome
- Fruit yielde6
- Direction
- increasede6
- Comparator
- inoculated controle6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Anthracnose crown rot of strawberry, caused by Colletotrichum acutatum”
e6“Fruit yield was also significantly increased by natamycin as compared with the inoculated control”
Claim · model-written summary
Monterey and Portola were more susceptible to disease than Fronteras.
- Taxon
- strawberryFragaria ×ananassae1
- Material
- Monterey and Portolae7
- Outcome
- disease susceptibilitye7
- Direction
- more susceptiblee7
- Comparator
- Fronterase7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Anthracnose crown rot of strawberry, caused by Colletotrichum acutatum”
e7“Differences in disease susceptibility were observed among cultivars evaluated, with Monterey and Portola more susceptible than Fronteras”
Claim · model-written summary
QoI resistance carried no detected fitness penalty in pathogenicity or virulence.
- Taxon
- strawberryFragaria ×ananassae1
- Outcome
- fitness penalties in pathogenicity or virulencee2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Anthracnose crown rot of strawberry, caused by Colletotrichum acutatum”
e2“there were no detected fitness penalties in pathogenicity or virulence”
Claim · model-written summary
QoI resistance was associated with the G143A mutation in the cytochrome b gene.
- Taxon
- strawberryFragaria ×ananassae1
- Gene
- G143A mutation in the cytochrome b genee2
- Outcome
- Resistancee2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Anthracnose crown rot of strawberry, caused by Colletotrichum acutatum”
e2“Resistance was associated with the G143A mutation in the cytochrome b gene”
Claim · model-written summary
High levels of QoI resistance were detected in California isolates of C. acutatum.
- Taxon
- strawberryFragaria ×ananassae1
- Interactor
- Colletotrichum acutatumColletotrichum acutatume1pathogen
- Outcome
- quinone outside inhibitor (QoI) resistancee2
- Qualifier
- high levelse2
- Setting
- California isolatese2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Anthracnose crown rot of strawberry, caused by Colletotrichum acutatum”
e2“high levels of quinone outside inhibitor (QoI) resistance were detected in California isolates of the pathogen”
The same questions in other papers
azoxystrobin · Colletotrichum acutatum · Fragaria x ananassa (strawberry)Positive and negative results
1 paper in the same direction as this paper · 4 in the opposite direction
- positive
- positive
- positive
2 papers more in this group
See all 6 papers →natamycin · Colletotrichum acutatum · Fragaria x ananassa (strawberry)Results agree
1 paper in the same direction as this paper
- positive
transplanting · Colletotrichum acutatum · Fragaria x ananassa (strawberry)Results agree
1 paper in the same direction as this paper
- positive
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.