There’s nothing soft or fluffy about downy mildew, a devastating disease that rapidly kills basil plants of virtually every marketable variety. After rearing its ugly head in Europe 10 years ago, it hit the shores of the U.S. in 2007 and is now responsible for wiping out basil crops from Florida to Hawaii, and all states in between. Its appetite for high humidity, lower temperature environments was hungrily fueled by this winter’s relatively mild climate across the United States and Mexico.
What is downy mildew? It’s a fungus that spreads mainly through windborne spores. The spores germinate and release a parasite that attacks and kills basil leaves rapidly, sometimes within hours of infection. There is no known cure for this disease. The most effective control program is defense: the regular application of fungicides (organic ones, in our case) before the disease strikes. As with another now-endemic basil pest – fusarium – the most promising preventative strategy may be developing a downy mildew-resistant strain of seed.
Until then, basil lovers must literally weather the challenges basil farmers and packers face: planting up to double the usual basil acreage during wintertime to plan for likely downy mildew crop failures; experiencing increasing losses at both the harvesting and packing levels; and overall degradation of basil quality.
On a positive note, the effects of downy mildew should substantially diminish as spring approaches and days get longer, drier and warmer. Basil inventories throughout the Northern Hemisphere will increase with this favorable trifecta, and downy mildew will hopefully be downgraded to a nuisance till next winter.