Abstract
Phytophthora blight, caused by Phytophthora capsici, is one of the most economically significant diseases of bell pepper in the United States. Over the past several decades, isolates of P. capsici exhibiting resistance to mefenoxam and other fungicides have been reported. Fungicide resistance coupled with an increased market for organically grown crops has led to interest in biological control as a disease management option. In this work, an isolate of Bacillus subtilis (AFS032321) was evaluated for control of Phytophthora blight of bell pepper in the greenhouse and field. A 28% active ingredient wettable powder formulation of the strain was applied as a soil drench at transplanting prior to inoculation. Treatment with this formulation of B. subtilis significantly reduced the area under the disease progress curve (AUDPC) by up to 52% compared to untreated control plants in greenhouse tests. Comparisons between applying the biocontrol weekly after seeding for 5 weeks versus a single application at transplanting (5 weeks) indicated no significant benefits of additional applications. The formulation of B. subtilis reduced disease caused by a mefenoxam-resistant isolate of P. capsici, while mefenoxam failed. The biocontrol efficacy of formulated strains was not affected in different soil types or potting media. However, disease was more severe in sandy soils. In field experiments that were conducted with a mefenoxam-sensitive isolate, disease incidence and severity of Phytophthora blight were significantly reduced at all rates of B. subtilis in 2019 except the 16.8 kg ha −1 rate. In both years, mefenoxam was more effective than B. subtilis in controlling disease in the field. B. subtilis did not affect the spatial dynamics of pathogen spread within rows. While the precise mechanism(s) of action is unclear, in vitro dual-culture tests suggest direct antagonism, as B. subtilis significantly inhibited colony growth of P. capsici. AgBiome has recently released a new formulation of the AFS032321 strain named Theia, with higher active ingredients for commercial applications and biocontrol of P. capsici.
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Claims 11
Claim · model-written summary
Bacillus subtilis reduced disease progress by up to 52% in greenhouse tests.
Verbatim
e0“Treatment with this formulation of B. subtilis significantly reduced the area under the disease progress curve (AUDPC) by up to 52% compared to untreated control plants in greenhouse tests.”
t0“Bell Pepper”
Claim · model-written summary
Additional weekly applications gave no significant benefit over one transplant application.
Verbatim
e0“Comparisons between applying the biocontrol weekly after seeding for 5 weeks versus a single application at transplanting (5 weeks) indicated no significant benefits of additional applications.”
t0“Bell Pepper”
Claim · model-written summary
The formulation reduced disease caused by a mefenoxam-resistant P. capsici isolate.
- Taxon
- bell peppert0
- Treatment
- The formulation of B. subtilise0
- Interactor
- P. capsici
.jpg?width=60)
Phytophthora capsicie0pathogen - Second interactor
- B. subtilis
Bacillus subtilise0biocontrol_agent - Outcome
- disease caused by a mefenoxam-resistant isolate of P. capsicie0
- Direction
- reducede0
- Comparator
- mefenoxame0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
e0“The formulation of B. subtilis reduced disease caused by a mefenoxam-resistant isolate of P. capsici, while mefenoxam failed.”
t0“Bell Pepper”
Claim · model-written summary
Mefenoxam failed against disease from the resistant isolate.
- Taxon
- bell peppert0
- Treatment
- mefenoxame0
- Interactor
- P. capsiciPhytophthora capsicie0pathogen
- Outcome
- disease caused by a mefenoxam-resistant isolate of P. capsicie0
- Direction
- failede0
- Comparator
- The formulation of B. subtilise0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The formulation of B. subtilis reduced disease caused by a mefenoxam-resistant isolate of P. capsici, while mefenoxam failed.”
t0“Bell Pepper”
Claim · model-written summary
Biocontrol efficacy was unaffected by soil or potting medium type.
Verbatim
e0“The biocontrol efficacy of formulated strains was not affected in different soil types or potting media.”
t0“Bell Pepper”
Claim · model-written summary
Disease was more severe in sandy soils.
Verbatim
e0“disease was more severe in sandy soils”
t0“Bell Pepper”
Claim · model-written summary
In 2019 field tests, Bacillus subtilis significantly reduced blight incidence except at 16.8 kg ha −1.
- Taxon
- bell peppert0
- Treatment
- B. subtilise0
- Outcome
- disease incidencee0
- Direction
- reducede0
- Qualifier
- except the 16.8 kg ha −1 ratee0
Not reportedComparator
Verbatim
e0“disease incidence and severity of Phytophthora blight were significantly reduced at all rates of B. subtilis in 2019 except the 16.8 kg ha −1 rate.”
t0“Bell Pepper”
Claim · model-written summary
In 2019 field tests, Bacillus subtilis significantly reduced blight severity except at 16.8 kg ha −1.
- Taxon
- bell peppert0
- Treatment
- B. subtilise0
- Outcome
- severity of Phytophthora blighte0
- Direction
- reducede0
- Qualifier
- except the 16.8 kg ha −1 ratee0
Not reportedComparator
Verbatim
e0“disease incidence and severity of Phytophthora blight were significantly reduced at all rates of B. subtilis in 2019 except the 16.8 kg ha −1 rate.”
t0“Bell Pepper”
Claim · model-written summary
Mefenoxam controlled field disease more effectively than B. subtilis in both years.
Verbatim
e0“In both years, mefenoxam was more effective than B. subtilis in controlling disease in the field.”
t0“Bell Pepper”
Claim · model-written summary
B. subtilis did not affect pathogen spread within rows.
- Taxon
- bell peppert0
- Treatment
- B. subtilise0
- Outcome
- spatial dynamics of pathogen spread within rowse0
- Direction
- did not affecte0
Not reportedComparator
Verbatim
e0“B. subtilis did not affect the spatial dynamics of pathogen spread within rows.”
t0“Bell Pepper”
Claim · model-written summary
B. subtilis inhibited P. capsici colony growth in vitro.
- Taxon
- bell peppert0
- Interactor
- P. capsiciPhytophthora capsicie0pathogen
- Second interactor
- B. subtilisBacillus subtilise0biocontrol_agent
- Outcome
- colony growth of P. capsicie0
- Direction
- inhibitede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“B. subtilis significantly inhibited colony growth of P. capsici.”
t0“Bell Pepper”
The same questions in other papers
Bacillus subtilis · Phytophthora capsici · Capsicum annuum (sweet pepper)Results agree
2 papers in the same direction as this paper
- positive
- positive
Bacillus subtilis · disease · Capsicum annuum (sweet pepper)Results agree
7 papers in the same direction as this paper
- positive
- positive
- positive
4 papers more in this group
See all 8 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.