Garden Q&A: Tomato problems

Two tomato problems: little hard scars or rings of slasher-like cracks on the top of the tomatoes and/or roundish black rotten spots on the sides. The side spots grow big and may collapse in the middle. What are the causes and solutions?

The concentric rings on the shoulders of the tomatoes is rain check. It is a physiological problem associated with heavy rains. It’s worse after a dry period. Change in water uptake or fruit temperature may be the cause. It’s more common on fruits that don’t have good leaf cover shading the fruit. It has been observed that commercial fields with shade cloth have minimal rain check problems. Some tomato varieties are more prone to rain check. Note your varieties with rain check. Try to keep good leaf coverage—a challenge with rainy weather that favors leaf disease.

For the side spots, keep in mind that once a tomato has any tiny fungal infection or nick, either the fungi expands or bacterial rot gets in. The fungus is probably anthracnose. The solution is to pick fruit as soon as it colors. Bring it inside to ripen. Contrary to popular belief, this will not cause poor flavor, and it protects your fruits. Tomatoes do not need sunlight to develop good flavor once they begin coloring. With all the rain and humidity we have had, fungi are having a heyday. Bring your tomatoes in.

I had to pull out all lettuce seedlings for my fall crop. There are little green "worms" eating them bare and tons of black eggs everywhere. I removed the lettuce, green worms and all the eggs I could see. I just bought lettuce transplants. How can I avoid another infestation? If eggs I missed hatch, should I let the worms die off from lack of food and then replant? I will use a floating row cover this time. Or is it better to plant somewhere else?

The black balls you saw were not eggs. They were excrement from your multitudes of cabbage loopers. (Eggs of cabbage looper caterpillars are tiny and pale yellow-white to green.) You can replant now. Move your lettuce bed if it's not too much trouble. Yes, use the row cover, especially if you plant in the same area. It's always a good idea to first identify the pest and then read through the pest profile under Common Problems on the Grow It Eat It section of the HGIC website (extension.umd.edu/growit), for control options, life stages and behavior. All the better to outwit it.

University of Maryland Extension’s Home and Garden Information Center offers free gardening and pest information at extension.umd.edu/hgic. Click “Ask Maryland’s Gardening Experts” to send questions and photos.

Digging Deeper

Crane fly

Not giant mosquitoes or even in the mosquito family, crane flies are, well, flies. Often called mosquito hawks, these clumsy flyers are incapable of biting, stinging or much of anything except mating. While adult crane flies don’t eat, they do live in damp areas where they lay eggs that hatch into slim brownish larvae with big appetites. Larvae feed primarily on decaying plant material, so they are considered aids to decomposition, not pests. On the contrary, the larvae, also known as leather jackets, make dandy fish bait, particularly for trout. Birds are their main predator. When crane flies appear near outdoor living areas at night, they are probably attracted to lights, like many insects. Limit night lighting and, if they bungle their way indoors, escort them out gently. Their fragile extremities tend to break off.

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