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Plant Disease Clinic
This article was published originally on 7/15/1992
- Plum Pockets
Plum pockets is caused by the fungus Taphrina communis. Symptoms of plum pockets include the production of abnormally large, misshapen, hollow fruit. Infected fruit eventually turn brown, wither and fall from the tree. Once infected, the fruit cannot be treated. Effective control of the disease can be obtained by spraying an appropriate fungicide in the autumn after the leaves have fallen, or in the spring before buds begin to swell. Recommended fungicides include chlorothalonil, lime-sulfur, Bordeaux mixture, or a fixed copper fungicide.
- Vinca canker and dieback
Vinca canker and dieback is caused by a species of the fungus Phoma. The disease typically causes shoot tips, leaves, or stems to wilt and blacken. Plants become thin and weak. The disease is usually worse on plants under environmental stress. To control the disease, remove infected plants or prune out diseased plant parts. Improve vigor with fertilization and watering. Mulching may be beneficial. Avoid overhead watering. Control competition by weeds. A properly labeled fixed copper fungicide may be used when new shoots appear in spring.
- Fusarium root rot of pea
The fungus Fusarium solani f. sp. pisi can cause root rot of pea. Typical symptoms include a dark reddish brown discoloration of the roots, especially at the soil line. The roots and lower stem appear collapsed. Fusarium root rot and other root problems are favored by adverse environmental conditions. Cultural practices such as good tillage to prevent soil compaction, proper watering, proper fertilization, crop rotation, and the use of high quality seed can help reduce the problem.
- Testing for wilt diseases of shade trees
A proper sample must be submitted in order to test for wilt diseases such as Dutch elm disease, oak wilt, and Verticillium wilt. Samples should consist of several branch segments, approximately 1/2 to 1" in diameter and 12" in length, collected from symptomatic areas. If possible, collect from more than one area of the tree. Do not submit entirely dead wood. Wrap the samples in dry paper towels or newspaper, place in a bag, and box. Mail or drop off the sample promptly. Keep the sample in a cool place if you anticipate a delay before shipping. The samples can be dropped off at your local county Extension office or mailed directly to the Plant Disease Clinic, Room 12 Bessey Hall, Ames, IA 50011.
This article originally appeared in the July 15, 1992 issue, pp. 1992 issue, pp. 122-123.
IC-463(18) -- July 15, 1992