Gardening columnist Tim Daly answers the following questions from readers:

Question: Some of my garden plants are being troubled by aphids. I understand that lady beetles feed on these pests, and I plan to order a package of them from an online source. Once it arrives, I will release the insects into my garden. How effective are lady beetles at controlling aphids and other similar pestiferous insects? – Linda, Grayson

Answer: Linda, aphids are small, soft-bodied insects that have pierce-sucking mouthparts and feed on many landscape plants. They prefer fresh, lush succulent growth. The insects secrete a honeydew substance that promotes the growth of black sooty mold and carries diseases.

True, lady beetles are predators on aphids in addition to mealybugs and white flies. However, many times, the number of aphids greatly outnumbers the beetles. Purchasing lady beetles and releasing them into the environment is not practical since they will not stay in one place and will disperse throughout the area. Sometimes these insects are useful as a biological control in indoor environments such as greenhouses and conservatories.

If you are having issues with aphids, apply an insecticide labeled for their control. An example is insecticidal soaps, which are considered organic and have low toxicity — the chemical smothers the insects. You can also use a hose and wash them off the infested plants.

Q: Several tomatoes on my plants have rotted at the bottom of the fruit. What type of disease is causing this malady, and how can I stop it? — James, Buford

A: James the cause of the rot is not a disease, but rather a deficiency of calcium in the plant. The soil may have plenty of the nutrient. However, due to fluctuating soil moisture levels, going from very dry to moist to dry again disrupts the plant’s ability to absorb calcium.

The best course of action is to ensure the soil stays evenly moist. Use a two to four-inch layer of a fine texture organic mulch, such as pine straw, pine bark, or cypress bark. Doing soil will help reduce soil moisture loss in addition to keeping weeds under control.

Q: My fescuegrass lawn has thinned out significantly during the heat of the summer and a substantial amount of bermudagrass that has infested it. What can I do to get rid of it? I want to overseed with more fescue, and is now a good time to do so?

– Roger, Dacula.

A: Roger, when fescue grass and bermudagrass compete for the same area, the bermudagrass almost always wins. Fescuegrass is a cool-season grass. It prefers cooler temperatures, which are more conducive to its growth.

Bermudagrass requires warmer temperatures for optimal and will turn brown and go dormant during the cold weather. You should use RoundUp to control the bermudagrass. True, some of the fescuegrass will perish as well.

However, when the new seed is applied to these areas, it will grow and fill in these sections. Right now the weather is still too hot to put out seed. Wait until mid -September into early October to do so.

Timothy Daly is an Agricultural and Natural Resource Extension Agent with UGA Extension Gwinnett. He can be contacted at 678-377-4011 or tdaly@uga.edu.