Basil Downy Mildew

Basil downy mildew, scientifically known as Peronospora belbahrii, is a devastating fungal disease that affects most sweet basil plants. The disease first manifests as yellowing or chlorosis of the upper surface of basil leaves, followed by the appearance of grayish-purple fuzzy growth on the undersides. These fuzzy growths are actually spore-producing structures of the pathogen. As the disease progresses, the basil leaves may curl, become distorted, and eventually drop prematurely, leading to stunted growth and reduced crop yield. For more information on the signs and symptoms look here.

Basil downy mildew can spread rapidly through airborne spores, water droplets, and contaminated equipment or plant material. It poses a particular threat to commercial basil production, culinary herb gardens, and home gardeners who grow basil for personal use.

Effective management of basil downy mildew involves a combination of preventive measures and cultural practices. These include using disease-resistant basil cultivars, spraying fungicide control agents, ensuring proper air circulation and sunlight in the growing area, avoiding overhead irrigation, and maintaining good hygiene by removing infected plant debris.

Fungicides approved for use against basil downy mildew should be employed for commercial production, but it’s essential to follow proper guidelines and consider their potential impact on the environment. Early detection, prompt action, and proactive disease management strategies are crucial in mitigating the impact of basil downy mildew and preserving basil plant health. For the latest and most up-to-date control options for field-grown basil including currently registered fungicides please visit this Rutgers Plant and Pest Advisory page. You can also visit this Cornell University disease fact sheet. If you are a greenhouse grower of basil and need the latest and most up-to-date control options for greenhouse-grown basil please visit this Rutgers Plant and Pest Advisory page or the following Cornell University disease fact sheet.

Please note that if you suspect basil downy mildew on your plants, it is advisable to consult local agricultural extension services or plant disease experts for accurate diagnosis and specific management recommendations. It is also important to report your suspected infection at the Basil Ag Pest Monitor website. There specific instances are recorded, confirmed by basil downy mildew experts and logged onto the map allowing researchers and growers to identify disease hotspots.

Remember to regularly monitor your basil plants, implement preventive measures, and take appropriate action if you notice any signs or symptoms of basil downy mildew.

For more in-depth information please check out this blog: Basil Downy Mildew: Research Topics, Results and Reports.