Insecticide For Lettuce

Lettuce is a fast-growing vegetable that can be harvested for use in salads as well as many other recipes. This vegetable thrives outdoors in U.S. Department of Agriculture hardiness zones 2 through 10 and will grow in a variety of conditions. Depending on your location, however, your lettuce crop may fall victim to any number of pests that could damage or even decimate your planting. To prevent this from happening to you, equip yourself with knowledge of the most common pests affecting lettuce crops and take steps toward preventing them in your garden.

Common Lettuce Pests

1. Lettuce pests can be divided into three categories: weeds, diseases and insect pests. Because lettuce has a fairly short growing season, weeds can severely hamper the growth of a healthy crop. Diseases affecting lettuce crops are particularly common in warm, moist climates. Some of the most common diseases affecting lettuce crops are downy mildew, leaf spot, rot and a variety of bacterial diseases. Though many insect pests are likely to feed on lettuce crops, the most prevalent group of insect pests is caterpillars. Cutworms, armyworms, corn earworms and cabbage loopers damage the leaves and stems of lettuce plants while other insect pests like aphids, maggots and beetles can cause damage as well.

Controlling Weeds

1. For small gardens, picking by hand may be sufficient to control weed pests. In larger gardens, however, it may be necessary to use a chemical or natural herbicide. Some of the most effective herbicides for weed pests affecting lettuce crops are imazethapyr, pronamide, paraquat and sethoxydim. These herbicides can be used to control either perennial or annual weeds, though imazethapyr and pronamide are most effective against annual weeds. Weeds affecting lettuce plants can also be controlled through the use of deep plowing techniques, preplant germination or soil solarization.

Disease Management

1. Because weather is a major factor in whether or not lettuce crops succumb to disease, management efforts can only go so far. Some diseases can be treated, however, once they develop. Fungus-related diseases like downy mildew can sometimes be controlled with fungicides like azoxystrobin and implementing irrigation methods to drain the soil may help to prevent or control other diseases like bottom rot. Chemical methods of disease control for lettuce plants often include ingredients like copper, sulfur or maneb. In some cases, weeds are responsible for introducing pathogenic viruses to lettuce crops so mulching and plowing may also help with disease management.

Managing Insect Pests

1. Caterpillars, the largest group of insect pests affecting lettuce crops, can destroy seedlings and feed on the crown and leaves of mature plants. Maggots attack emerging seedlings; beetles feed on leaves, stems and roots; and wireworms damage germinating seeds. Insecticides are the most commonly used method of insect pest control on lettuce crops — some of the most effective pesticides include azadirachtin, diazinon and pyrethrins. In recent years, several reduced-risk pesiticides like spinosad and methoxyfenozide have also become popular. As an alternative to chemical control methods, introducing parasites or predatory insects into the lettuce crop can help control some insects pests, and mulching and plowing methods may also help reduce pest populations prior to planting.