The near-wilt pathogen, F. oxysporum f. pisi race 2, has much in common with the wilt pathogen. It remains indefinitely in the soil. Its best growing temperature is the same as for the wilt fungus. It is unlike the wilt pathogen in that the best temperature for disease development in the soil is higher and follows that for the growth of the fungus.

Near-wilt is worse in warmer seasons, on late varieties, and on late plantings. The fungus that causes near-wilt establishes itself on all soil types. It enters the water-conducting vessels of the pea through either the root tips or at the cotyledonary node. The wilt fungus does not progress far enough up the stem to infect the seed, but the near-wilt fungus frequently travels the entire length of the stem. As a result, seeds (especially those of the dwarf, late varieties) are likely to become infected. The fungus can be disseminated to other fields by infected seed and surface-contaminated seed and by spreading diseased vines on the soil.

Workers at the Wisconsin Agricultural Experiment Station discovered one line of breeding material that appeared to have complete field resistance to near-wilt. The resistance is inherited as a single dominant gene. Delwich Commando was introduced as the first variety completely field-resistant to wilt and near-wilt.

BACTERIAL BLIGHT, although caused by a bacterium, behaves like some of the fungal blights. The disease occurs on all above-ground parts of the plant, but is most pronounced on the leaves, stems, and pods. The symptoms first appear as small, irregular water-soaked spots, which may enlarge to one-eighth inch across on the foliage and to about one-fourth inch on the pods. Streaks usually appear on the stems. The translucent leaf lesions usually turn to a golden-brown color. In time the lesions coalesce. The leaves wither and become papery. The stem lesions elongate and remain water-soaked or turn brown with age. On the pods the spots become slightly sunken but retain the water-soaked character. They may occur on the checks of the pods or along either suture.

The causal organism, Pseudomonas pisi, is carried over winter chiefly through the seed, either as a contaminant on the seed surface or internally as an infection. The organism can infect cowpea, sweet pea, hyacinth bean, and the perennial or everlasting pea. Possibly the bacterium overwinters in the vines of those hosts, although the seed-borne character is most important.

Spread and damage depend on weather. Spattering rains carry the bacterium from one plant to the next. Seedling infection may kill the plant. Usually, however, such infection provides the inoculum for spread to adjacent healthy plants. The extent of spread depends upon the frequency of rainy periods. If' they occur often enough, within the span of a week, the primary infection from a tiny amount of infected seed can spread over a large field. In continued rainy periods the crop might be destroyed. Dry weather may check the disease.

The bacterium enters the plant through the stomata and through wounds. Any practice, therefore, that injures the plants, especially when they are wet, serves to increase infection. Hail injury frequently paves the way for rapid and severe infection.

The most effective control of bacterial blight is the use of disease-free seed. A 4 or 5-year rotation, recommended for the control of other pea diseases, would certainly eliminate diseased vines as a primary source of infection.

W. T. SCHROEDER is a graduate Of the University of Idaho and the University of Wisconsin. While doing graduate work at the University of Wisconsin, he conducted surveys of diseases of peas for several large canning companies in Wisconsin and Minnesota. From 1941 to 1943 he was with the Green Giant Co. of Minnesota as plant pathologist. Since 1944 he has conducted research on the diseases of canning vegetables at the New York Agricultural Experiment Station of Cornell University, at Geneva, N. K, where he is professor in the division of plant pathology.

Lima bean scab.