What Are the Most Common Disease & Pest Problems With Pepper Plants?

Mosaic

• Mosaic is the most common disease problem in peppers, according to the University of Hawaii Extension. Caused by a virus, several types of mosaic affect peppers, including cucumber mosaic and tobacco mosaic. Symptoms include yellow mottling and distorted leaves, as well as small, malformed fruit. Mosaic is hosted by a number of weeds, so eliminating weeds before planting can help prevent this disease. Cucumber mosaic is also spread by aphids, and tobacco mosaic can be transmitted through the plants' seeds. Thorough sanitation of all surfaces in your greenhouse prior to germinating seeds can help prevent tobacco mosaic.

Bacterial Spot

• Caused by a number of different bacteria, leaf spot can infect both peppers and tomatoes. It causes spots on the leaves, which begin as irregular water-soaked areas and eventually become purplish-gray depressions with black centers. The spots can also appear on the fruit, beginning as water-soaked areas that eventually become raised and scab-like. Bacterial spot is transmitted through pepper seeds, both on the surface and inside the seeds.You can treat seeds with hot water or a solution of 1 part bleach and 4 parts water to combat bacterial spot. Another common pepper disease, Cercospora leaf spot, is similar in appearance, but is actually caused by a fungus and often occurs in hot, wet conditions.

Anthracnose

• Anthracnose is caused by three different types of fungus, and appears on peppers as sunken spots, often with a mass of yellow or pinkish spores. Promoted by hot and moist conditions, anthracnose occurs most often on ripe fruit, but can also infect immature fruit, stems and leaves. Anthracnose can survive over the winter in pepper seeds, as well as in debris from dead plants. Anthracnose is treatable by a number of fungicides including Maneb, Quadris and Cabrio.

Aphids

• Among the most common insect pests on a number of different crops, aphids of several varieties can infect peppers. Green peach aphids are the most common. They are tiny -- less than 1/8 inch -- and appear oval-shaped green or yellow insects with or without wings. Aphids feed on leaves by sucking the juices out of them, which causes mottling and discoloration. These insects also spread diseases like mosaic, and can contribute to sooty mold fungus. The best way to control aphids is to let their natural enemies like lacewings, damsel bugs and ladybugs flourish -- this means avoiding the use of pesticides unless some other insect pest absolutely demands it.

Beet Armyworm

• Beet armyworm is an especially damaging pest in the South and Southwest, but can appear farther north as well. Usually about an inch long, beet armyworms are green or black moth larvae with light stripes that can damage pepper plants by eating leaves and buds. Hand-picking is an effective way to manage this pest in cases where only a few are present, but more often, insecticide sprays will be necessary. Confirm, Intrepid, and Spintor are a few effective insecticides, and sprays containing Bacillus thuringiensis var. azawai usually do the job.