First Report of Downy Mildew Caused by <i>Peronospora belbahrii</i> on Sweet Basil (<i>Ocimum basilicum</i>) in Arkansas

Considerable progress has been made in managing Peronospora belbahrii, an oomycete pathogen that causes basil downy mildew, since 2007, when it was first detected in the United States (U.S.). Conventional fungicides have been registered and shown effective against P. belbahrii in replicated experiments in recent years. Unfortunately, because of their specific modes of action and P. belbahrii biology, some are at risk for resistance development which has been documented outside the U.S. Sweet basil varieties have been developed and commercialized, with most exhibiting good to high levels of resistance to basil downy mildew. Knowledge about conditions favorable for infection and disease development has resulted in the identification of cultural practices for managing basil downy mildew in the greenhouse. Practices being implemented include fans to move leaves, thus preventing water deposition and decreasing relative humidity, lighting at night to mitigate sporulation, and temperature modification to suppress disease development. While downy mildew can be more effectively managed today, growers still experience losses, particularly when conditions are highly favorable for disease development. None of the organic fungicides or programs tested have provided adequate control for susceptible varieties; and limited testing has been done on resistant varieties to date. This review aims to summarize effective basil downy mildew management tools, in particular downy mildew-resistant varieties, environment modifications, and fungicide applications.

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A Diagnostic Guide for Basil Downy Mildew

Standish

Raid

Pigg

et al. 2020

Plant Health Progress

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Downy mildew, caused by the oomycete pathogen Peronospora belbahrii, is one of the most important diseases affecting sweet basil worldwide. Field- and greenhouse-grown basil may be affected, and crop losses are observed as the reduction of marketable leaves during both the production and postharvest handling stages. As an obligate biotroph, P. belbahrii cannot be cultured and maintained without live plant tissue, which may complicate efforts to diagnose and identify the causal agent. Thus, the goal of this diagnostic guide is to outline the appropriate methods required to identify basil downy mildew based on the symptoms of the disease and signs of the pathogen. Additionally, methods for pathogen identification, pathogen isolation, storage of single-sporangium cultures on live plants, and pathogenicity testing are described in detail.

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First Report of Downy Mildew Caused by Peronospora belbahrii on Sweet Basil (Ocimum basilicum) in Arkansas

Cited by 5 publications

References 3 publications

Peronospora belbahrii (basil downy mildew)

Peronospora belbahrii (basil downy mildew)

Effective Downy Mildew Management in Basil Using Resistant Varieties, Environment Modifications, and Fungicides

A Diagnostic Guide for Basil Downy Mildew

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