Bordeaux mixture is still the most widely used fungicide for downy mildew. The concentration of the mixture and the number of applications required for satisfactory control depend on the susceptibility of the variety and the severity of infection likely to occur in a given locality. In vineyards in New York, three applications of bordeaux mixture, 4-4 100, are satisfactory for control under most conditions. The sprays should be applied immediately before bloom, immediately after bloom, and 7 to 10 days later. On varieties extremely susceptible to foliage infection an additional application when the fruit is about half-grown may be necessary to prevent infection Of the newly developed leaf area, especially if the disease is already established on other parts of the vine. When bordeaux mixture is used, the addition of a spreader or spreader-sticker does not increase control. Tests in New York vineyards indicate that the applications to control the fruit-rot phase need not be so thorough as we once considered necessary if the applications are timed properly in relation to the bloom period. Fixed-copper fungicides with lime added (4 pounds of lime for each pound of metallic copper) are somewhat less effective than bordeaux mixture of an equivalent concentration of copper. The fixed-copper materials are less injurious than bordeaux mixture and are preferable in vineyards where high rates of application are necessary for the thorough coverage required for effective control of certain insects.

POWDERY MILDEW, caused by Uncinula necator, is present in most grape-growing areas of the Eastern States. In the Pacific Coast States it is considerably more destructive; when temperature and humidity are favorable it is capable of destroying the entire crop of vinifera grapes in unsprayed vineyards. In the East the fungus primarily attacks the foliage and cluster stems; it appears on the berries only in unusually favorable seasons.

Powdery mildew infection appears as a superficial, grayish-white growth on the shoots, tendrils, cluster stems, berries, petioles, and upper surfaces of the leaf blades. This powdery fungus growth can be rubbed off with the fingers; then the discolored epidermis is exposed. Conidia, produced in abundance on the surface of the feltlike fungus growth, spread the disease to other parts of the vine. Brownish-black perithecia, formed on the surface of the infected areas, constitute the overwintering stage of the fungus.

Unlike black rot and downy mildew, this disease is favored by periods of low rainfall and only moderately high relative humidity (between 70 and 80 percent).

Powdery mildew is controlled in the East by the copper fungicides applied for black rot or downy mildew. When ferbam is used in the early sprays for the control of black rot or when powdery mildew is the only disease requiring control, the application of a copper-containing fungicide 2 or 3 weeks after bloom and again about 2 weeks later is effective. Bordeaux mixture, 2-4--100, or an equivalent concentration of a fixed copper and lime, is adequate under most conditions, because the disease is relatively easy to control on grapes. Sulfur sprays or dusts recommended for the control of powdery mildew on the west coast produce marked injury to the foliage of the bunch grapes growing in the Eastern States.

DEAD ARM, caused by Cryptosporella viticola, is responsible for recurring losses in many vineyards in the Northeast, where vineyards in which 10 to 20 percent of the vines show harmful effects from dead arm are not uncommon. The disease has also been reported on the Pacific coast.

Its most prominent and destructive effect is the dead arm that gives the disease its name. In June and July the foliage on the shoots from affected canes, or arms, that have not been killed by the disease is yellowed, dwarfed, crimped, and ragged at the margin. Such abnormal conditions are the result of a canker on the arm or on the trunk below the point of attachment of the arm. A dry rot in the woody part of the trunk spreads in both directions from the canker. As the canker enlarges each year, other arms may become similarly affected. If they are not removed, the entire vine above the canker eventually dies. As the season progresses, many of the affected leaves drop from the vine and the remaining leaves develop a normal green color. The healthy foliage and shoots from unaffected parts of the vine and from adjacent vines soon cover up the affected growth and thus make it difficult to detect diseased vines in midsummer, On the green shoots, petioles, cluster stems, and tendrils, small reddish-brown lesions develop from infections of the current season. In years favorable for late-season infections, lesions on the cluster stem may become sufficiently numerous to be instrumental in causing berries to drop from the cluster stem. The following spring the lesions appear on the canes as brownish-red elevations or as longitudinal cracks, from which stringy fibers of host tissue are exposed.

The fruit may be infected in some seasons. The rot is like that produced by the black rot organism. The affected berries become dark gray, shrivel, and produce mummies with surface pustules. The color is not so black as that of black rot, the shriveling is less convolute, and the pustules are slightly larger and less numerous.

Conidia are formed in pycnidia, which develop in the lesions on the shoots, arms, and trunks. In the spring shortly after the buds open, the pycnidia swell and exude long tendrils of spores. Most of the spores are dispersed early in the season, but production of spores may continue throughout the summer.

Under conditions favorable for germination, the spores infect the tender, succulent growth. Trunk and arm cankers may result from infections in pruning cuts and other wounds. Pycnidia are usually not developed on the current season's growth. Shoot lesions in most years therefore are most prevalent on the first 12 or 18 inches of cane growth. Although the causal organism has been shown to produce perithecia, the perfect stage is rare and probably is not important in perpetuating the fungus.

The control measures suggested for dead arm are the systematic removal of affected parts of the diseased vines and early-season spraying to prevent new infections. Care should be taken to prevent carrying the fungus to healthy vines on pruning equipment that might have become contaminated when used to cut through cankers on other trunks. Pruning cuts should be made at least 6 inches beyond the lower margin of the infection in order to make certain that the affected part is entirely removed. Early applications of bordeaux mixture have been recommended to supplement the control of dead arm. Three applications of ferbam, timed for the control of black rot, had no appreciable effect on the late-season infections that were unusually abundant in New York vineyards in 1950.

CROWN GALL, caused by Agrobacterium tumefaciens, may attack grape roots, trunks, and canes. It is common in most grape-producing areas, but it seldom does serious damage. European varieties and hybrids are generally more susceptible than the American varieties. In New York the Isabella is the only variety that has shown extreme susceptibility to the crown gall organism, although galls of considerable size have also been observed on other varieties, including Concord.

The galls may occur on any of the woody parts of the vine but usually are most abundant on the basal part of the trunk. The galls on the roots are more or less spherical, and are usually found near the ground line.

The control of crown gall on grapes is essentially the same as recommended for its control on other woody plants. Badly infested land should not be used for cultivation of the varieties known to be extremely susceptible. Care should be taken to avoid planting stock that shows evidence of galls on the roots or canes. Large galls that are present on the upper parts of the trunks or on the arms can be removed by pruning the arm or trunk some distance below the affected tissue or by renewing the vine by means of a shoot from the base of the vine. Removal of the old wood of the vine as Soon as the trunk begins to show a gnarled appearance is considered effective in reducing the incidence of trunk infections.

ANTHRACNOSE, caused by Elsinoe ampelina, is found on some grape varieties in the Eastern States, but usually is considered of minor importance in the North. Outbreaks are local and usually sporadic. The most susceptible varieties are Champion, Catawba, Campbell Early, Diamond, Norton, and Salem. The Concord, Delaware, Moore Early, and Niagara have been reported to be resistant.

The disease appears on the leaves as small, irregular, dark-brown, sunken spots, with dark margins. The spots on the fruits are usually larger, more sunken, and gray. Their margins are darker than the centers and give them a characteristic appearance from which the name "bird's-eye rot" was derived. Lesions also develop on the shoots, petioles, tendrils, and cluster stems like those of anthracnose on raspberries.

Frequently two or more lesions on the berries unite and cause the fruit to become dry and wrinkled. Shoot lesions may coalesce and cause the death of the terminal portion of the shoot.

Conidia are produced on the surface of the infections of the current season and also on the surface of lesions on overwintered parts of the vine. Those spores can spread the disease during most of the growing season. The perfect stage of the fungus develops during the winter in ascocarps present in the old cankers. The ascocarps are much like those of the raspberry anthracnose organism, Elsinoe veneta.

The control of anthracnose depends on spraying and on the removal of the more seriously affected parts of the vine at the time of pruning. Research men have recommended a delayed dormant application of 10 gallons of liquid lime-sulfur in 100 gallons of water followed by four or five applications of bordeaux mixture (8-8-100) when the new shoots are 7 to 8 inches long, just before bloom, immediately after bloom, 7 to 10 days later, and at the time when the berries are about half-grown. The applications of ferbam recommended for the control of the black rot might also control anthracnose.

OTHER DISEASES generally localized or appearing only in some seasons include bitter rot (caused by Melanconium fuligineum), ripe rot (Glomerella cingulata), cotton root rot (Phymatotrichum onmivorum), armillaria root rot (Armillaria mellea), measles (cause unknown), and verticillium. wilt (Verticillium albo-atrum). A number of other fungi have been observed on grape foliage but their effect on the vines is usually negligible.

ALVIN J. BRAUN holds degrees from the University of Chicago, University of Wisconsin, and Oregon State College. His early experience with the diseases of small fruits was as research assistant, from 1938 to 1942, at the Oregon Agricultural Experiment Station. From 1943 to 1945 he was with the Guayule Research Project at Salinas, Calif., and the Emergency Plant Disease Prevention Project in Ohio. Since 1945 he has been in charge of investigations of diseases of small fruits at the New York State Agricultural Experiment Station at Geneva, where he is an associate professor in the division of plant pathology.