Ripe rot, caused by the fungus Vermicularia capsici, is more damaging than anthracnose on pimiento peppers in the South. Fruits may be infected when green but show no spotting until they turn red. At this stage, fruits in the field may show only small, inconspicuous yellow spots. When they are picked and held in the containers in warm, moist air, however, the spots enlarge so fast that many fruits become unfit for use within 24 hours. The fungus, like the one that causes anthracnose, can grow into the seed cavity and infect the seed. Seedlings grown from such seed show spotting of the seed leaves, but there is little injury to the foliage.

The organism causing bacterial spot of the leaves also causes a damaging spotting of the fruits. The spots, roughly circular, are raised in small blisterlike swellings that may be one-fourth inch across. They turn brown and become cracked, roughened, and warty. In damp weather various decay-producing organisms can enter through the spots.

Mosaic diseases of peppers cause serious losses in yield and quality of the fruit. The most common are those of tobacco mosaic, cucumber mosaic, and the tobacco etch virus (Marmor erodens). They sometimes are found in combined infections of the same plant.

Younger leaves of plants affected with the tobacco mosaic virus are mottled with yellow-green spots and may be slightly curled and crinkled. Infected plants often show a streaking of some of the branches. Later the leaves drop; often the branches die. Some green strains of the virus cause little if any mottling of the fruits, but with others the fruits may turn yellow and have a wrinkled surface. Yellow strains sometimes cause a mottling of the fruit.

The cucumber mosaic virus causes a leaf mottling like that of tobacco mosaic, but the young leaves are more often curled upward at the edges and the darker areas are raised and slightly blistered in appearance. Such leaves often are narrow and pointed. The plants often are abnormally short and bushy. Fruits sometimes are misshapen and have dark raised spots on their surface. One strain of the virus causes large yellow rings on the leaves and fruits.

The tobacco etch virus often affects peppers and causes a mottling of the leaves that may be much like that of cucumber mosaic. At times it is very mild. With the etch virus alone, there is no evident mottling of the fruit. When sweet peppers are infected with both the etch and tobacco mosaic viruses, however, the fruits are yellowed and wrinkled and show rough, slightly raised, circular spots.

NONPARASITIC DISEASES like those that attack tomatoes sometimes affect peppers. Sunscald and blossom-end rot area common cause of considerable loss of sweet peppers. Blossom-end rot is caused by the same factors that lead to its development in tomatoes. Sun-scald injury is particularly severe where peppers have been defoliated by leaf spot diseases.

The symptoms of both disorders consist of large areas with a dry, light-colored, papery appearance. Blossom-end rot, however, occurs on or near the blossom end of the fruit. Sunscald injuries may occur at any point. With spots of both types, the injured areas are commonly overgrown by fungi that later give them a dark appearance.

AS FOR CONTROL: The prevention of disease in the seedbed is of prime importance, because several of the most serious pepper diseases are caused by organisms that may be present on the seed or infest the soil.

It is best not to grow seedlings in soil that recently has been planted with peppers; if that must be done, the soil should be disinfected by one of the means mentioned for tomato seedbeds (see page 460).

The seed should be disinfected before, planting. One method consists of soaking seed for 5 minutes in a 1 2,000 solution of bichloride of mercury (corrosive sublimate). After treatment, it is washed for 15 minutes in running water and dried at once. The treatment will destroy organisms present on the surface of the seed. It is particularly effective in the control of bacterial spot.

Some organisms, such as those that cause anthracnose and ripe rot, also may cause internal infection of the seed. That can best be prevented by harvesting seed only from sound fruits, as surface treatments will not destroy the fungus within the seed. Treatment with bichloride of mercury does not protect seedlings against damping-off, and it is advisable to treat the seed afterward with Arasan, Thiram 50, or Phygon.

Losses from wilt diseases can be reduced by crop rotation and the avoidance of fields where wilt diseases have previously been destructive. Poorly drained, moist soils should be avoided. The variety College No. 9 chili is resistant to the fusarium wilt, which damages hot peppers in the Southwest.

The use of fungicides for the control of leaf spot and fruit rot diseases of peppers has not become the general practice that it is with tomatoes. Peppers sometimes are sprayed with a 6-6 100 bordeaux mixture or a neutral copper fungicide used in a formula that gives the equivalent of 1 1/2 pounds of actual copper to 100 gallons of water. Neutral copper dusts with a 5-percent copper equivalent also have been used. The dithiocarbamate fungicides zineb, nabam. (used with zinc sulfate), and ziram also can be used at the strengths commonly employed With tomatoes (page 461).

The copper compounds seemed to give the best control of bacterial spot, but that is not necessarily true with such diseases as cercospora spot and anthracnose fruit rot.

If leaf spot diseases appear in the seedbed, the plants should be sprayed at once. When such diseases appear on the leaves of occasional plants throughout the field, it is wise to apply a fungicide and continue applications at intervals of 7 to 10 days, depending on the weather. If leaf spot diseases do not appear until late in the season, however, the use of fungicides may not be profitable. There is evidence that the copper fungicides may cause some injury to peppers, particularly when several applications are made during the season.

In general, the methods for reducing losses from mosaic viruses are the same as those for the prevention of losses in tomatoes. Care in handling seedlings is as important with peppers as with tomatoes.

Aphids commonly infest peppers. It is essential to control them, especially in the seedbed. Because peppers are commonly infected with the cucumber mosaic virus, perennial hosts of that virus should be destroyed near seedbeds and in and along the margins of the field. It is best to try to avoid having pepper fields next to cucumber, muskmelon, and celery fields because they all are highly susceptible to cucumber mosaic.

The varieties Rutgers World Beater No. 13, Burlington, and Yolo Wonder are resistant to the tobacco mosaic virus but are not resistant to the viruses causing cucumber mosaic and tobacco etch.

S. P. DOOLITTLE is a principal pathologist in charge of investigations of tomatoes, peppers, cucurbits, and certain other vegetable crops in the division of vegetable crops and diseases of the Bureau of Plant Industry, Soils, and Agricultural Engineering. He was graduated from Michigan State College and, after graduate study in plant pathology at the University of Wisconsin, joined the Department of Agriculture in 1918. He was one of the earlier workers on virus diseases of vegetable crops.