Watching plants slowly wilt and die after their stems turn black leads to frustration and anger. Blight is the all-purpose name for a number of fungi in the soil that affects plants in this way. Easy to get and hard to eradicate, blight can quickly ruin one plant or a whole garden full.
Blight can come early in the planting year or much later, depending upon the type of fungus. The infestation is normally noted when the stem near the soil begins to turn dark brown or black. Later blight may affect the stem along joints. As the condition worsens the leaves begin to turn yellow and fall off the plant. If there are vegetables already growing the blight may begin to rot them also.
Keeping blight from a garden is impossible. Winds, insects and birds all bring it from one infected garden to another. Blight can enter the soil from other infected plants from neglected greenhouses. Once it enters the soil it becomes hard to clean out. The fungus can survive for years in the ground until it builds up sufficient numbers to become a problem. A number of soil treatments, both chemical and organic, exist that claim to help control blight already in the soil.
Many plant varieties have been developed to be blight-resistant. This is especially true for tomatoes, which are very susceptible to fungus. If the tomato seedling has some combination of the letters VFHNT on the label then it has some ability to ward off blight and other diseases. Peppers are very similar to tomatoes, but potatoes have very little protection against blight. Never use potatoes from last year's crop to grow a new crop.
When blight is discovered a gardener needs to take steps to prevent the transmission to other plants. All parts of an infected plant are taken from the garden and destroyed. Never use a tool on or near any plants unless it has been cleaned with soap and water. Do not reuse infected soil or allow it near clean soil. Because the fungus overwinters in the soil remove any trace of plant material it needs to survive. It is important the gardener protect himself from fungus spores entering his respiratory system. Always wear a breathing mask when around infected plants.
- Cornell University; Managing Late Blight in Tomato and Potato – An Essential Part of Gardening; Potato; Margaret Tuttle McGrath; 2010
- North Dakato State University; Questions on: Tomatoes; Ron Smith
- University of Maine; Early Blight Of of Tomato; 2010
- Cornell University; Tomato: Disease Resistance Table; 2011
Jack Burton started writing professionally in 1980 with articles in "Word from Jerusalem," "ICEJ Daily News" and Tagalong Garden News. He has managed radio stations, TV studios and newspapers, and was the chief fundraiser for Taltree Arboretum. Burton holds a B.S. in broadcasting from John Brown University. He is a 26-year veteran of the U.S. Navy/Navy Reserves and the Navy Seabees.