Paper · 2023 · Plant Disease

Efficacy of Organic Fungicides for Downy Mildew in Field-Grown Sweet Basil

Margaret Tuttle McGrath

2
claims
4
verbatim quotes
6
citations
2
research areas
✓
Open access

Abstract

Downy mildew is a common, widespread disease affecting basil leaves. No tolerance for disease symptoms, especially on leaves for fresh consumption, necessitates management. Six replicated experiments were conducted between 2010 and 2016 with field-grown basil of a susceptible cultivar exposed to naturally occurring, wind-dispersed sporangiospores of Peronospora belbahrii to evaluate fungicides approved for use on organically produced crops and products in development. Products tested currently registered for use on basil in the U.S. and labeled for downy mildew were Actinovate (Streptomyces lydicus), Companion (Bacillus subtilis), Cueva (copper octanoate), Double Nickel (Bacillus amyloliquefaciens), Forticept EP #1 (thyme oil), Milagrum Plus (Bacillus subtilis), Organocide (sesame oil), Oso (polyoxin D zinc salt), OxiDate (hydrogen dioxide), Procidic (citric acid), Regalia (Reynoutria sachalinensis extract), Stargus (Bacillus amyloliquefaciens), and Trilogy (neem oil). Most are biopesticides. A conventional fungicide, Revus (mandipropamid), was included in most experiments as a positive control. Applications were made weekly to foliage with a backpack sprayer starting before symptoms were seen, except in 2013 when disease onset was early and 2015 when applications were made twice weekly. Organic treatments tested in 2013 started with a soil drench application around the base of plants two days after transplantation. Fungicide efficacy was assessed based on incidence of symptomatic leaves rather than disease severity because there is no tolerance for disease on fresh-market herbs. None were effective based on weekly severity assessments or AUDPC values, confirming results from other researchers that downy mildew cannot be effectively managed with organic fungicides applied to susceptible basil cultivars.

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Claims 2

Intervention effectobservedoriginal resultno effectmeasured

Claim · model-written summary

Organic fungicides were ineffective against downy mildew in susceptible basil cultivars by severity and AUDPC assessments.

Treatment
organic fungicidese0
Interactor
Peronospora belbahriiPeronospora belbahriie1pathogen
Outcome
downy mildewe0
Direction
None were effectivee0

Not reportedComparator

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Ocimum basilicum
Ocimum basilicum · TaxonCastielli · CC BY-SA 3.0 · Wikimedia Commons ↗
Peronospora belbahrii
Peronospora belbahrii · Interactor · picture from its Wikimedia Commons categoryForest and Kim Starr · CC BY 3.0 us · Wikimedia Commons ↗

Verbatim

e0

“None were effective based on weekly severity assessments or AUDPC values, confirming results from other researchers that downy mildew cannot be effectively managed with organic fungicides applied to susceptible basil cultivars”

✓ located verbatim in the source · abstract, characters 1607–1833 · show in text ↑
e1

“sporangiospores of Peronospora belbahrii”

✓ located verbatim in the source · abstract, characters 333–373 · show in text ↑
Recommendationauthor interpretationoriginal resultnegativebasis n/a

Claim · model-written summary

The authors conclude that organic fungicides cannot effectively manage downy mildew on susceptible basil cultivars.

Interactor
Peronospora belbahriiPeronospora belbahriie1pathogen
Outcome
downy mildew cannot be effectively managede0

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Ocimum basilicum
Ocimum basilicum · TaxonCastielli · CC BY-SA 3.0 · Wikimedia Commons ↗
Peronospora belbahrii
Peronospora belbahrii · Interactor · picture from its Wikimedia Commons categoryForest and Kim Starr · CC BY 3.0 us · Wikimedia Commons ↗

Verbatim

e0

“downy mildew cannot be effectively managed with organic fungicides applied to susceptible basil cultivars”

✓ located verbatim in the source · abstract, characters 1728–1833 · show in text ↑
e1

“sporangiospores of Peronospora belbahrii”

✓ located verbatim in the source · abstract, characters 333–373 · show in text ↑

fungicide · Peronospora belbahrii · Ocimum basilicum (basil)Positive and negative results

5 papers: 4 positive, 1 negative or no effect

4 in the opposite direction

  1. positive
  2. positive
  3. positive

1 paper more in this group

See all 5 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.