![]() ![]() They isolated the genes that resist both early blight and late blight. Greenhouses and cold frames are expensive, but without direct rainfall, copper fungicides stay on the leaves and are very effective at preventing late blight.īreeders at the NCSU Mountain Horticultural Crops Research and Extension Center have an active tomato breeding program. Growing tomatoes under cover is another solution – one that has worked very well for us. When the weather turns dry in late August and September, late blight may never appear. First, not every year is a late blight year. The third problem with copper is that it washes off in the rain.ĭespite all this gloom and doom, organic tomato culture is not hopeless. ![]() The leaves appear water-soaked and black. It blows in from other states and drifts down on the tops of plants. Unlike early blight, late blight is air borne. Once the invaders infect a leaf, that leaf is lost, so copper must coat every leaf before the fungal spores arrive. It does battle with fungal spores on the leaf surface. The second problem is that copper is a preventative fungicide. Excessive spraying over several years can damage your soil indefinitely. The first is that copper is a nutrient at low concentrations but it is toxic to plants at high concentrations. In my view, copper fungicides are the only organic solution to late blight.Ĭopper fungicides have three problems. None worked outside but copper worked great under cover. We tested compost tea, hydrogen peroxide and copper sulfate – all organically approved control methods. That disappointing experience led to a SARE-funded research project on our farm and on Pat Battle’s farm in Celo. A few days after I saw the first blight damage, the foliage was gone, the fruit were infected, and the crop was a total loss. One August I was anticipating my best tomato crop ever when ten days of rainy, misty weather moved in. Late blight is the same disease that led to the Irish potato famine. I suggest putting on the Jaws soundtrack. The first step in managing late blight is to get in the proper frame of mind. Late blight, pictured to the left, is a completely different disease. Remember that tomatoes are heavy feeders and a long crop will need supplemental nutrition to keep the plant growing actively. In most years early blight is a nuisance but will not threaten the success of your crop. Correct pH, regular irrigation, and soil supplements matching the soil test results are some of the best ways to ensure vigorous plants. The main organic management method for early blight is vigorous plants. Removing yellow leaves with the characteristic target spot also helps, if you can take the time to do that at your scale. Organic and plastic mulch help avoid that initial infection from the soil. In dry years tomatoes can often outgrow early blight so yield is not greatly affected. Early blight is soil borne and infects the tomato plants from soil that is splashed onto lower leaves and then it moves up the plant. ![]() Despite their similar names, early and late blight are different diseases. This photo to the right shows early blight on tomatoes. NCSU offers a collection of scary pictures that may help identify the particular problem that affected your plants. Is there any way to eliminate this? Thanks!īlight is both a specific and a generic term for leaves that wither and die. Great info! I’ve been having tomato leaf blight on almost all my tomato plants. Hello - Thanks for the latest newsletter. ![]()
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