White rust (Albugo occidentalis) was determined to be one of several diseases causing heavy loss in a commercial spinach area in Oklahoma; previously it had been known in Texas only.

A virus disease of lettuce known as virus necrosis, or brown blight, was found on greenhouse lettuce in Illinois, besides Indiana, where it was first observed.

On onions, smut (Urocystis cepulae) was found in Colorado and downy mildew (Peronospora destructor) in Texas. A minor infection of the latter was noted in one locality in Idaho. Both diseases are rather widespread, smut in most northern onion-growing areas, and downy mildew more or less throughout the country.

The disease of soybean known as top necrosis, streak, or bud blight, caused by a virus resembling the tobacco ring spot virus, had been recognized in Indiana, Ohio, and Iowa before 1943. During our survey, it was found to be generally distributed in the Central States from Ohio west to Kansas and South Dakota.

The charcoal rot, or ashy stem blight, organism (Macrophomina phaseoli), was found in Oregon; in one place it was causing a severe root rot of pumpkin and squash. That disclosed a considerable jump in the known occurrence of the fungus, which has been rather widely reported on many different kinds of plants in the southern two-thirds of the country, especially west of the Mississippi, but had never been encountered in Oregon before, on any host.

Some diseases were observed to be more widely distributed than previously realized in States where they were already present. Among these, to mention only two, alfalfa bacterial wilt (Corynebacterium insidiosum) was found for the first time in the main alfalfa seed-producing areas in Minnesota, its known range in Wisconsin also was extended northward, and in some other States it was found to be more prevalent and widespread than had been suspected. The onion bulb nematode (Ditylenchus dipsaci), which has been known for some time on a few farms in two locations in New York, was found in another district in a small portion of one field.

The detection of new and potentially important sources of damage was only one aspect of the assistance given by the emergency program to crop production. In many activities it supplemented the work of Federal and State agencies in such matters as the factors that influence infection and spread, the identity and cause of obscure diseases, the determination of distribution and importance of specific diseases, the prediction of the development of a disease during the season, the determination of subjects on which research was needed, and the places where insecticides and fungicides were urgently needed by farmers.

The following crop disease developments, not necessarily new, but nonetheless important, are selected from several hundred cases to illustrate the contributions of another part of the emergency program.

The potato rot nematode (Ditylenchus destructor) is a bothersome nematode pest on potatoes in northern Europe. As a result of our work, in cooperation with State officials, the first definite knowledge of its presence on potatoes in the United States was made known. In 1943 infected potatoes were found on three farms in Idaho. Immediate action by officials of the Idaho Department of Agriculture prevented the growing of potatoes on one of the farms, and on the others they stipulated that potatoes could be grown only in designated fields other than those in which the pest occurred in 1943. The agency also prohibited the moving and use of manure from a feed lot, where infected cull tubers were fed, until tests could demonstrate whether the organism could be spread in that way. In 1944, all farms in the vicinity were resurveyed. Nematodes were present in tubers from two farms and from two other nearby farms.

In 1943, the crop of one commercial rutabaga section of Virginia suffered a loss estimated at 10 percent. The trouble was observed and the cause was determined by a field worker as due to a deficiency of boron, which had not previously been suspected in the area. The growers lost more than $20,000 that year, but the information as to the occurrence and cause of the loss, placed in the hands of the State extension pathologist, permitted the application of known control measures the following year.

I cite the epidemic of late blight (Phytophthora infestans) on potatoes and tomatoes in the lower Rio Grande Valley of Texas as an example of the application of current crop-disease information to the forecasting of future developments.

Late blight was found widely distributed on the fall crops of both hosts in late 1943 and early 1944, the first time in several years that the disease had occurred on tomatoes in the valley. The significant feature of the prevalence of late blight on the relatively small fall crop was the threat that this abundant source of infection would carry to the important spring crops, which were just being planted at that time and which overlapped the fall crops during the early stages of growth. The danger was so serious that growers were warned in time to undertake preventive measures, and extra supplies of fungicides and insecticides were ordered. The weather remained favorable the next 3 months, and by March the disease had increased to epidemic proportions. In most undusted potato fields all of the foliage had been killed, and the stems were dying by the middle of March, with a total loss of the crop of affected plants, since most were just approaching the flowering stage. The effectiveness of dusting was strikingly evident, but only half of the 10,000 acres of potatoes were dusted. After March, the weather became less favorable and the disease was checked.