Q: My very old mimosa tree has black gum spots on the trunk. Dolores Barrash, Atlanta

A: It is a sad fact that mimosa trees, despite their beautiful flowers, are very susceptible to a specific disease: mimosa wilt. The widespread fungus lives in the soil. It enters the tree through the roots and travels upward. Over a couple of years' time, leaves turn yellow, wilt and the limb dies. Eventually the whole tree is dead. Late in the progress of the disease, the trunk will exude gum. That’s what you’re seeing on your trunk. There is nothing you can do about the disease. It only affects mimosas, so you can plant any other tree you find attractive in that spot.

Q: Why would my tomatoes have white meat inside? My opinion is that the plants are GMO and that’s causing this anomaly. My grandmother’s tomatoes had amazing sweetness and flavor. Faith Parker, email

A: There are no GMO tomatoes commercially available to cultivate, either by gardeners or farmers. Modern tomatoes have been improved by breeding better plants, as has been done for hundreds of years, not by gene transfer. Heirloom tomatoes might have tasted better, but they were also more likely to get diseases and have poor yield. I believe high temperatures in summer explain why you had tomatoes with white interiors. This is a common occurrence.

Q: I am about to move into my first home and the lawn is zoysia. I’ve been told I need a reel mower. Can you recommend a good one? Chesler Lindsey, Marietta

A: For zoysia, a reel mower is not absolutely necessary, but a sharp blade on your rotary mower is! Mowing with a dull blade will make the lawn look brown after cutting. This is due to the ragged grass that a dull mower blade leaves behind. Start with a sharp blade in spring and plan to sharpen or replace it in early July.

Q: I recently bought some Verry Cherry Plums from the grocery. They were delicious! Can I grow them here? Where can I buy the trees? Kathy Smith, Woodstock

A: This plum/cherry hybrid could grow in Georgia, but you won’t be able to find a tree for sale. Achieving the hybridization was very difficult, so the folks who were able to do it have patented their trees. They only allow a few certified large growers in California to cultivate and harvest the fruit trees. Controlling the source allows the hybridizers to be repaid for years of effort.

Listen to Walter Reeves' segments at 6:35 a.m. on “Green and Growing with Ashley Frasca” Saturday mornings on 95.5 WSB. Visit his website, www.walterreeves.com, follow him on Twitter @walterreeves, on Pinterest, or join his Facebook Fan Page at bit.ly/georgiagardener for more garden tips.