Anthracnose alone or with accompanying dieback apparently may occur in all regions where coffee can grow. No wholly satisfactory control is known for it. The fact that dead branches are replaced by new growth tends to allay the fears of growers or pathologists and means that interest lags in developing intensive control measures.

Disease-resistant strains are badly needed. Varieties of coffee have been found in east and central Africa that are highly tolerant to anthracnose die-back. They are being tested in Africa and have been introduced into Latin America for further study. It seems that the use of resistant plants is a promising way to combat it.

Cooperative projects have been started to study spray treatments in Costa Rica. Of several fungicides tested, Fermate was found to be best to keep seedbed and nursery plants free from anthracnose. It also keeps young field transplants free from infective dieback until they are well established in the plantation.

THE COFFEE BERRY DISEASE is a comparatively new disease of coffee. It has been found in Africa, the Belgian Congo, and Kenya. It has apparently increased in severity in the past few years. It is due to a specialized race of the anthracnose organism, Colletotrichum coffeanum var. virulans, that is peculiarly adapted to infecting fruits. The first symptoms are small, brownish spots, which become glazed, enlarge, and finally get a pinkish color. It is common on coffee grown at higher elevations, where as much as 50 percent of a crop may be destroyed. Its life history is not wholly understood.

Considerable work has been done on methods of control since 1950. The use of sprays has been studied but has given no results of practical value. Some varieties are more resistant than others. Research workers hope to breed varieties of higher degrees of resistance and to introduce that resistance into the regular commercial lines of coffee in the severely diseased regions.

THE THREAD BLIGHT DISEASE, also known as black rot in the Orient is reported in many countries in both hemispheres. Often it is localized in occurrence, but it can cause considerable losses. This is especially true in parts of south India, central Costa Rica, and like regions. It weakens trees and intensifies Colletotrichum dieback.

This tropical fungus Pellicularia koleroga occurs in moist regions and is one of a typical group of thread producers. It occurs in part as thick, traveling threads, tightly glued along the under sides of branches. A thread that reaches a leaf petiole sends out a side shoot to follow it. A broad, tissuelike pellicle is formed on the under side of the leaf by fanlike growths of the fungus hyphae. During this period of apparently superficial attack, the fungus can be torn from the host surfaces, but affected leaves darken, wither, and die.

If the fungus is left undisturbed, petioles of diseased leaves are loosened from branches but are held attached by fungus strings, which permit the leaves to hang swinging in the air like small, black rags. When moist weather comes, the surface of the fungus pellicle on under parts of leaves becomes Powdery with spore-bearing bodies.

No thorough study has been made of the temperatures at which sporulation occurs, but vegetative growth of the fungus is good at temperatures ranging from 75 F. to 90 , with greatest development at 83 . It grows poorly at 54 and is completely inhibited at 97 . Much research remains to be done on this parasite and its life history.

Different changes in plantation culture have been tried in order to combat the disease. Clean culture, fertilizing, variations in shade, and defoliation methods have had little effect. It was quickly eliminated in Africa and eastern lands where bordeaux spray was applied to control rust. After many years without black rot, as rust-resistant varieties have been introduced in parts of India and coffee has not been sprayed for rust control, thread blight has again returned with serious consequences. Spraying of individual trees with bordeaux mixture in Central America has given good results. The newer copper sprays have been found to be of equal value. The copper compounds often are injurious to coffee foliage, but that disadvantage is outweighed by the effectiveness of the compound against thread blight.

FRUIT SPOT, or brown eye leaf spot, is a bothersome, common, fruit- and leaf-spotting disease. Its causal organism was named Cercospora coffeicola. in 1881. It is found on coffee the world over but is not severe in much of the Orient. It is of greater economic importance in Latin America than is ordinarily admitted. Defoliation actually is one of its worst effects. It produces severe decay on the fruit.

Fruit infections result in a characteristic black dry rot. The pathogen is seed-borne. The leaf spots are large; usually only a few occur on a leaf, although one on a leaf is often enough to cause it to drop. The spots have been confused with the American leaf spot, but they are quite different. Cercospora spots have wide brown edges and a light center, with black specks. The disease seems to occur under a wide range of conditions and may be especially severe in nurseries. It grows fairly well even at temperatures less than 54 F. and is relatively good in growth from 61 to 90 . The greatest growth is at 75 to 83 . It grows weakly at 97 . The disease is more severe in coffee exposed to the sun than in well-shaded coffee.

A common and sound way of reducing the disease is to develop a canopy of shade over the plantation. Proper attention to soil protection and adequate moisture content seem to have good effects. No effective fungicide has been found.

ROSELLINIA ROOT ROT is one of several root rots to which coffee is susceptible. The fungus that causes the most trouble is Rosellinia bunodes, which is found in both hemispheres. Compared with some of the serious leaf parasites, this disease causes almost negligible losses, but the death of occasional trees may cause so much concern among growers that they attach greater importance to the disease than actual economic losses justify.

The planter first notices a diseased tree by its slightly yellowed and grayish-green leaves, which soon wilt and turn black when the tree dies. The base of the trunk of such a tree usually has bark that is slightly roughened just above the ground and is tightly appressed to the wood below. Dead roots that have been dead long enough are dark, with a hairy, black growth under the bark a condition that extends up the tree trunk. The bark in those parts has black spots and streaks in the wood. Usually when one tree dies the one next to it will succumb somewhat later.

The cause is an apparently weak-growing fungus, whose growth habits provide a key to control measures. Diseased areas may be isolated by digging a trench around them and throwing the soil that is dug from the trench in towards the disease center. Some planters do not follow this practice but simply replant. Replanting is done even in trenched-in areas. As trees die, it is best to dig them immediately and remove all large roots from the soil. A wide, deep hole should be left open for 6 or 12 months. Afterwards it may be filled in and replanted with a healthy seedling, which often grows without contracting the disease. At times, however, that treatment fails, and digging must be repeated, with a longer interval between removal of the diseased seedling and replanting with a new seedling. In regions where the disease is believed to be common, jungle land is cleared for coffee with unusual care to remove stumps and large roots of wild trees. Corn or another crop is grown on the land for 2 years before it is made into coffee plantings. The practice seems to help against early infections of rosellinia; root rot.

THERE ARE several other root-attacking fungi other species of Rosellinia and species of Fomes, Pellicularia, and Ganoderma. They all cause much the same symptoms as described for Rosellinia bunodes. Another root rot; Armillaria mellea, as it occurs in Tanganyika causes a curious splitting of roots, trunks, and larger stems, and leaves the bark hanging more or less loose in strips. All root rots are handled as Rosellinia is.

FREDERICK L. WELLMAN Since 1943 has been agriculturist and consultant in plant pathology for the Office of Foreign Agricultural Relations of the Department. of Agriculture. He spent more than 4 years on El Salvador as a pathologist and worked in coffee. He is now stationed as chief agriculturist at the Inter-American Institute of Agricultural Sciences, Turrialba, Costa Rica, where since 1947 he has devoted himself to a study of diseases of tropical plants, particularly coffee. He was once employed for 2 years as a pathologist for a commercial concern in Central America, and from 1930 to 1943 served as a pathologist in the Bureau of Plant Industry, Soils, and Agricultural Engineering. Dr. Wellman participated in the mission sponsored by the Point IV program in 1952 to study coffee diseases in all parts of the world.