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Act Now to Fight Tomato Blight

Clean up to improve next year’s crop

Tomato blight attacks your tomatoes by way of the leaves. The blight starts at the bottom of the plants and progresses upward. The lower leaves turn yellow-green, and oblong spots with concentric rings in the middle appear mid-leaf. Soon the leaves brown and fall. Plants are weakened and, without shade, fruit sunburned. So you don’t want to give the blight a foothold, for it will spread.
    If you have tomato plants still in the ground, destroy any that are contaminated; avoid composting unless  temperatures in the  pile exceed 140 degrees.
    If you have already placed your tomato cages and stakes in the garden shed, you may want to take them out of storage for treating.  The spores of tomato blight can overwinter on the wire cages or stakes that support plants during the growing season.
    A recent research study demonstrated that tomato plants grown with new cages and new stakes have far fewer incidences of blight than plants grown with previously used cages and stakes. Microbiologists were able to culture spores of the organisms that cause blight in tomatoes from cages and stakes in both fall and spring.
    But treating used cages and stakes with a diluted bleach solution prior to storage and before placing them around the tomato plants in the spring significantly reduced the blight problem, the researchers also reported.
    They recommend spraying the cages with a 10 percent bleach solution (one part by volume of bleach and nine parts by volume water). Spray the wires until they drip, making certain that the joints are thoroughly soaked. If you use stakes, dipping them in the same percent solution brings the bleach into all of the pores of the wood, plastic or steel. Vessels for dipping can be made from a large diameter piece of plastic pipe or a piece of gutter capped at one end. Wear latex gloves to avoid skin contact with the bleach.
    Growing tomatoes in the same soil where potatoes were grown the previous year also resulted in greater occurrence of blight in tomatoes, the researchers reported. The blight appears to be carried over on the unharvested small potatoes left in the ground. If you grow both tomatoes and potatoes in the same garden, let a full year lapse before rotating tomatoes to where you previously grew potatoes.


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