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Pines. Colonies of inch-long green or yellow worms with black or brown heads appear, chewing off needles at a great rate. When you poke at them they rear up indignantly and stiffen to simulate needles. These are sawfly larvae. Control: Any strong stomach-contact poison. Ash. The blossoms wither and become dark clusters which stay on all winter. These are flower galls, caused by a mite. Control: Spray with malathion and a good sticker in the spring when buds are swelling. Dogwood. New leaves are small and pale, turning red prematurely. Twigs and whole branches die. Examination of the inner bark and sapwood low on the tree will show discolorations. This is crown canker, caused by a fungus called Phytophthora cactorum which attacks through lesions in the trunk and roots. Control: Trace the lesions well back, excavate them thoroughly, and apply shellac; feed the trees to help them resist further invasion, and spray early with a fungicide. |
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