Blackwelder column: Fungus hurting impatiens, beetle eating bean leaves

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Virginia buttonweed is showing up in some lawns. It is difficult to control and may need several applications of weed killer. Submitted photo.
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Rhizotonia can be blamed for failing impatiens. Submitted photo.
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Larva of the bean beetle feed on the leaves of bean plants. Submitted photo
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A bean beetle works on a leaf. Submitted photo.

SALISBURY — This week brought Rowan County lower temperatures and much needed rainfall, but it also meant some major problems for home gardeners. Below are samples of questions that may be of interest.

Q: My sweet corn crop looks very good, but there are no kernels in the middle of the cob. I didn’t have this problem last year. What can I do to prevent this?

A: Unfilled kernels are probably due to incomplete pollination. Sweet corn should not be planted in one long row but a couple of shorter rows.(I asked about this and the grower had a long single row of sweet corn.) Corn is wind pollinated so a single row of corn only has enough pollen for adjacent stalks when the wind blows in one of two directions. Corn in plantings of several short rows can have ample pollen spread when the wind blows in any direction. Kernels can also be missing if the corn has matured during a period of drought.

Q: Our impatiens are dying and we have always had very good luck with them. What is the cause and what can we do to prevent this?

A: There are two very serious fungal diseases in impatiens this summer. Downy mildew and root rot caused by Rhizoctonia sp. have had catastrophic effects on impatiens this summer. Control using fungicides at this point may be ineffective. Removal of dead and dying plants may be the most realistic alternative. New Guinea impatiens, coleus, begonia or other available bedding plants are safe to reset in the affected area. Go to the N.C. State University Plant Pathology website for more detailed information.

Q: My green beans have a yellow fuzzy bug making holes in the leaves. What is this insect and how do I control it?

A: Your insect pest is most likely Mexican bean beetle larvae. Crop residue destruction, usually by plowing soil 6 inches, destroys all stages of the beetle. Rotating your vegetables and using resistant varieties are very important in controlling future outbreaks. North Carolina State University has more information online about the beetle.

Q: I have this weed in my lawn (homeowner brought weed in for identification) that I have tried to kill with Roundup with no success. What is this weed and how do I kill it?

A: The weed was identified as Virginia buttonweed. The weed is difficult to control. For best results use repeated applications of lawn weed control products containing 2,4-D, clopyralid and dicamba.

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

www.rowanmastergardener.com

rowan.ces.ncsu.edu

www.rowanextension.com

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