Growing vegetables at home continues to be a popular trend, according to national surveys. Whether you have a large garden spot or just a few plants growing in containers, the satisfaction of eating produce your hands have tended is tremendous. Unfortunately, growing veggies is not without trials and tribulations. Here are a few common problems we see at this time of year.
Chances are real good you’ll find tomatoes in nearly any home garden. Just a few well-grown tomatoes can easily feed a family. But red flags are quickly raised when the fruit or plants don’t look right. Rotting fruit and yellowing foliage are two of the most common tomato complaints.
Fruit that turns black on the bottom is called blossom end rot. The black or dark spot on the blossom or bottom end of the fruit is typically not soft or mushy, but a firm rot. Blossom end rot is not caused by a pathogen. The problem is related to calcium levels in the developing fruit, but is brought on by fluctuating soil moisture, root pruning or excessive nitrogen fertilization.
Blossom end rot can occur at any time during fruit development, but is most common when fruits are one-third to one-half grown (or just turning ripe), usually in early June. Varieties with large fruit are more seriously affected than smaller types. I don’t recall ever seeing blossom end rot on cherry tomatoes.
Frequent rain or irrigation, interspersed with dry conditions is usually responsible for this problem. What can you do about blossom end rot? Since it is not a pathological disease, the problem must be addressed through cultural practices. First, pick off all of the affected fruit. The best control for blossom end rot is to maintain a uniform supply of moisture through regular irrigation and mulching. Mulching will keep the soil more uniformly moist during dry periods. Provide cultural conditions that promote good drainage. Avoid prolonged wet and dry cycles. Also, do not deeply cultivate the soil around the plants while weeding. This can destroy roots, limiting water uptake. The next set of tomatoes to ripen should be OK, provided the plant’s water needs are met.
Another tomato problem we often see is plants showing excessive twisting, curling and deformed shoots and leaves. This could be either one of the tomato viruses, or exposure to hormone-type broadleaf herbicides.
One plant here and there randomly affected would indicate a viral disease, whereas a whole section or row of tomato plants affected would point to herbicide injury.
There is nothing that can be done for virus-infected plants other than to pull them from the garden to prevent the further spread of the disease. Herbicide injury can be from direct exposure to drift, or, as often is the case, from hay used as mulch from a pasture recently treated with broadleaf herbicides. Even manure can be the source of herbicide if the cattle had recently grazed treated hay.
Spider mites can also plague tomatoes. Almost invisible, mites feeding results in yellow stipple leaves as they suck out cell sap. If mites get really bad, fine webbing can be seen. Routine use of insecticides, especially carbaryl (Sevin) can result in outbreaks of spider mites. Mites are difficult to control since they are not insects. Low populations of mites can be managed with repeated high-pressure water sprays directed to undersides of leaves, or with organic insecticides like neem oil or insecticidal soap.
Squash is a popular garden vegetable that comes with its own set of problems.
One that is particularly frustrating is squash vine borer. The symptom is simple — a healthy, vigorous squash plant suddenly wilts and dies a few days later. Close inspection of the stem reveals the problem.
The squash vine borer is the larval stage of a clear-wing moth. She lays her eggs on the squash vine about the time the plant starts to bloom. The worm then bores into the stem and feeds protected inside the stem. If you discover the intruder in time, you can sometimes save the plant by slitting the stem, killing the larva and then placing soil over the stem. Dusting the stem with a registered insecticide about the time of bloom may also repel the adult moth. But once the worm is inside the stem, insecticides will not work.
“My squash is blooming, but there is no fruit!” This is a common complaint, especially in early summer. Many gardeners don’t realize that the squash plant bears its male and female parts in separate flowers. Typically, the first flowers produced on a squash plant are males, which are incapable of producing fruit. When both male and female flowers are present, then pollination can occur, and fruit will be produced. The swollen female flower stalk is actually the immature fruit, while the flower stalk bearing the male flower is long and slender.
Male and female flowers may both be present, and still no fruit could occur if there is no pollen transfer. Bees are the main pollinators of squash, and individual squash flowers open only once, and only during the first half of the day. So, if it is rainy or windy in the morning, bees won’t be working the plants. Also, careless use of pesticides could kill your pollinators.
If you have both male and female flowers, and still no fruit, then you can play the role of pollinator. Taking a small paint brush, dab the brush on the yellow anthers bearing the pollen, and transfer the pollen to the stigma of the female flower.
Finally, if you planted yellow squash, but the fruit is multicolored and/or warty, your plants did not cross-pollinate with some other vegetable. They have a virus, which is a disease transmitted by insects. Unfortunately, there is no remedy, and to limit further spread, pull and discard affected plants.
Keith Hansen is Smith County horticulturist with the Texas A&M AgriLife Extension Service. His web page is http://EastTexasGardening.tamu.edu. His blog is http://agrilife.org/etg.