Where is Basil Downy Mildew?? – Gardeners Needed To Determine

Basil downy mildew is a new disease in the US.  Before it swept through Europe (first report in 2001), it was very obscure, having only been reported once – Uganda in 1933!

I am looking for help determining how widespread this disease is.  I think it is common, based on the fact it has occurred in my garden every summer since first detected in the US (Oct 2007). It has been reported in 37 states, but there have been few reports with the limited monitoring that has been done so far, thus often we get only one report from a state.

I’d greatly appreciate help from gardeners throughout the US willing to grow basil outside in the ground or pots. If you are interested in this opportunity, please contact me, as the project coordinator, Meg McGrath. mtm3@cornell.edu.  I can provide seed and I also have images to assist with identification at: http://vegetablemdonline.ppath.cornell.edu/NewsArticles/BasilDowny.html.

Below I’ve added two photos so you can see downy mildew on basil, both on the upper and underside of the basil leaf.

Initial symptoms of downy mildew on upper surface of leaves is chlorosis occurring usually in sections because the pathogen cannot grow past major veins in the leaf.

Initial symptoms of downy mildew on upper surface of leaves is chlorosis occurring usually in sections because the pathogen cannot grow past major veins in the leaf. (Photo: Margaret McGrath)

Initial symptoms of downy mildew on upper surface of leaves is chlorosis occurring usually in sections because the pathogen cannot grow past major veins in the leaf.

Pathogen produces dark spores on the underside of leaves opposite symptoms on the upper surface. (Photo: Margaret McGrath)



Thank you for considering helping to detect this plant disease where you are gardening.

 

Associate Professor, Plant Pathology
Cornell University, NY

 

 

 

 

 

 

 

 

 

 

 


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