How to treat tomato pests and the best ways to mow your lawn: Garden advice from Dan Gill

Garden columnist Dan Gill answers readers' questions each week. To send a question, email Gill at gnogardening@agcenter.lsu.edu. 

I think I'm getting stink-bug damage on my long-awaited ripe tomatoes. Help! What is the best treatment for them? I also see large numbers of leaf hoppers. — Edwin

First, to put things into perspective, stink bugs are among the less destructive pests of tomatoes. Other problems that actually destroy or ruin the crop are far more serious, such as bacterial wilt (that will take the whole crop), tomato fruitworms, tomato hornworm, fruit rot, buckeye rot and blossom end rot.

Fruits fed on by stink bugs (and their commonly seen relatives leaf-footed bugs) are still good to eat. But the heavy feeding of stink bugs and leaf-footed bugs can lower the quality of the tomatoes by causing yellow spots or splotching.

These bugs are among the more difficult of the insect pests to control. But regular applications of the insecticide permethrin (Bonide Eight and other brands) about once a week following label directions should help reduce the damage.

Leaf hoppers cause little or no damage to tomato plants or fruit but may carry diseases. The permethrin will also control them.

For organic gardeners, pyrethrum or a combination of pyrethrum and rotenone will help control stink bugs. Again, it will take repeated and regular applications to keep the population down. Another option is to repel these insects using peppermint oil formulated for use as an insecticide (check online or at your nursery or feed store).

This is my first time growing tomatoes. They are producing plenty of fruit, but the leaves are turning yellow. Is this OK or do I have a problem? — Peter Lowery

By this time of the year, we often see yellow leaves in the lower parts of our tomato plants. These are the oldest leaves. Sometimes they are just dying of old age, but most often, these lower leaves are the first ones to be attacked by fungal diseases. The lower leaves have been around the longest and have had more time to become infected. You may see brown spots or brown areas in some of the yellow leaves, indicating disease problems. Remove the yellow leaves. They are of no use to the plant. And this may remove some of the diseases (dispose of these leaves rather than putting them in your compost pile).

Spraying your tomatoes regularly with a fungicide labeled for use on tomatoes beginning earlier in the season is a good way to reduce disease problems this time of the year. Spraying now would slow progress of the diseases if you think it is warranted. But we are in the latter part of the tomato-growing season now. The main crop is already set, and we are harvesting at this point. So spraying this late may not be as critical.

Is it good to use a mulching mower to mow St. Augustine? Or is it better to use a mower with a bag and bag the clippings? Should I allow the grass to bloom and set seeds to thicken the lawn? — Chris Sanders

Yes, you can use a mulching mower to mow your St. Augustine lawn. Do be sure to mow frequently enough so that you are not cutting overly large pieces of leaves off when you do mow. Using a mulching mower is great because you do not have to stop and empty the bag, and the finely chopped grass clippings go back into the lawn. This returns mineral nutrients to the lawn and reduces the need for fertilizer.

Although you may occasionally see flower spikes in your lawn grass, St. Augustine grass does not produce viable seeds.

See pictures from our Photowalk in the swamp with Brett Duke (copy) — Palmettos and other palms can be planted now, while the soil is warm.
Photo by Larry Wilkinson

Garden tips

PALM TIME: Plant palms during the summer through August, as they establish best when planted into warm soil. Select hardier palms such as cabbage palm, windmill palm, Mediterranean fan palm, Canary Island date palm, date palm, palmetto and needle palm. Keep them well-watered while they become established.

GIVE THEM WHAT THEY WANT: After planting bedding plants, water them in with a half-strength solution of your favorite water-soluble fertilizer. This gets them off to a good start.

THINK SMALL: When buying pesticides, ask for a recommendation for the least toxic material that will do the job, and then buy the smallest container available. Large containers take years to use up, and by then, the pesticide has often lost its effectiveness.

LAWN WATCH: Chinch bugs, which are most damaging during hot, dry weather, often begin to show up in late June and July. Look for new irregular dead areas that enlarge fairly rapidly. The grass will have a dry, strawlike appearance. Treat with permethrin, bifenthrin, cyfluthrin or other labeled insecticides to prevent extensive damage. Follow label directions carefully.

SEASONAL CUTBACKS: Cut back early summer-flowering perennials in the garden when they finish flowering to keep the plants looking attractive and, in the case of some perennials, encourage more flowering.

KEEP PARSLEY IN PLACE: When parsley sends up its flower stalks, or bolts, its productive season is over. However, the tiny flowers attract and provide food for parasitic wasps that help control other insects. So, consider leaving your blooming parsley in place until flowering is over before removing it.