| [Image: Okra galling] |
| [Image: Galling on radish ] |
| [Image: Root-knot female on cuke] |
Gardeners are often unaware of a serious pest waiting for the spring vegetables to begin growing. These pests are small, microscopic animals called nematodes, and they attack the roots of many plants commonly grown in the garden. There are two major types of nematodes that cause the most problems for vegetables.
Root-knot nematode has the distinction of being the most widespread and destructive. It attacks the roots of just about every vegetable we grow. This pest does have one unique feature that makes it easy to recognize. When the nematode moves into the root and begins feeding, the area around the nematode swells and results in knots or galls that are visible on the root system. Some vegetables such as tomato, okra, and butterbeans seem to develop the largest galls.
The other nematode that damages some vegetables is the reniform nematode. This nematode is fairly widespread but seems to be a problem primarily to gardens in Baton Rouge and New Orleans. This same pest is by far the most important nematode to cotton farmers in the state but so far has not been a serious threat to gardeners. Reniform nematode does not cause any distinctive feature to roots of plants that it invades and is difficult to recognize in the garden.
If nematodes are a problem in the home garden, there are several symptoms to be on the lookout for. High populations of nematodes at the time of planting can result in plants that are very small, weak and unproductive. These plants cannot survive any serious stress such as drought and heat. If the population is moderate at planting, then they may grow fairly well initially but fall to produce for long periods of time. Be suspicious of nematodes if plants start developing yellow leaves, wilting during midday sun even when adequate moisture is present, shedding flowers or fruit, or dropping leaves.
Always use tomato varieties that have resistance against the root-knot nematode. Some that perform well in areas infested with this nematode include Better Boy, Big Beef, Bingo, Carnival, Celebrity, Champion, First Lady, Floramerica, Hawaiian Hybrid, Monte Carlo, Spectrum 882 and Terrific. These varieties have been deliberately bred to include a gene for resistance against the root-knot nematode. This resistance works great during our peak time of tomato production but may break down during extremely hot weather of July and August.
If you are unsure as to whether nematodes are a problem, you can have your soil checked to find out. Your local county agent can provide you with information on how to take a soil sample and send it in for you to have it analyzed.