Blackwelder column: Beware of heat and crown wilt

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SALISBURY — Excessive heat predicted for the weekend increases water stress on many plants and in some instances increases disease and insect pressure. With the impending hot weather, it is important not to overwater wilted plants. Some plants that normally withstand hot weather will wilt with sudden temperature spikes. Be sure to check the soil or media before watering wilted plants. Below are a few questions Cooperative Extension has received over the past few days.

Q: I have noticed many fields and some lawns are covered with a tall, yellow flower. They are beautiful and in full bloom now. They seem to be all over the county. Do you know what these plants may be?

A: The tall flowering plant is probably false dandelion. It can grow either as a winter annual or a biennial plant. To some it’s a weed, others enjoy it as a beautiful wild flower.

Q: My squash was doing well earlier in the season and now it is wilting and rotting. I checked and it was not squash vine borers. What is causing my squash plants to wilt and die?

A: Phytophthora crown rot, also known as Phytophthora blight, is one the most destructive diseases of vegetables in North Carolina. The crown rot pathogen, Phytophthora capsici, attacks peppers, tomatoes, eggplant, squash, pumpkin, cucumbers, watermelons and muskmelons. Symptoms vary depending on the crop and the part of the plant affected. On squash, a watery crown and fruit rot are common symptoms. Wilting and death soon follow. Fruit that comes in contact with contaminated soil develop dark lesions with concentric rings. Controlling crown rot can be difficult because the pathogen survives in soil for many years. Avoid planting in poorly drained or low areas, and avoid excess irrigation. Go to http://ncsupdicblog.blogspot.com/2012/06/phytophthora-crown-rot-of-squash. html for more complete information about the disease.

Q: I have cultivated blackberries and they have these strange white places the fruit. They don’t ripen evenly and I can’t use them. What is this problem and how do I control this?

A: Small fruit specialists at N.C. State University have identified the problem as white drupelet/sunscald. This condition is caused by UV radiation and a sudden increase in temperatures. Rainfall exacerbates the problem, with sunlight on wet berries plus high temperatures. The cultivar Apache shows more of this problem than any other variety, but white drupelets have been seen on many of the Arkansas varieties. White drupelet disorder is usually a problem early in the season and then disappears. The berries are still edible; they make delicious pies, juice and ice cream. More information can be found at http://teamrubus.blogspot. com/2012/05/white-grey-or-tan-drupelets.html

Darrell Blackwelder is the county extension director with horticulture responsibilities with the N.C. Cooperative Extension Service in Rowan County. 704-216-8970

www.rowanmastergardener.com

rowan.ces.ncsu.edu

www.rowanextension. com

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