DISEASES OF CULTIVATED PLANTS 507 



eased stock. Fungicides are apparently useless in combating this 

 disease. 



Root-Rot. The roots of the grape are known to be attacked 

 by several different fungi, especially when the root system has be- 

 come weakened or injured by other causes. Two forms of root-rot 

 are of sufficient importance to be mentioned here. The fungus known 

 as Vibrissea hypogasa is usually associated with insect injury, caused 

 either by Phylloxera or by the grape root-worm. It has been found 

 in New York, Pennsylvania, and Missouri, and appears to hasten the 

 death of plants, especially those on which the root-worm has been 

 at work. This root-rot can be prevented only by the destruction of 

 the insects which injure the root system and thus give the fungus 

 opportunity to gain a foothold. 



There is a root-rot of a more serious nature prevalent in and 

 chiefly restricted to Texas and New Mexico. This is caused by a 

 fungus known as Ozonium, which also attacks the roots of cotton 

 and a great variety of other plants. It is most destructive in the 

 black waxy, clay soils, which are very poorly aerated. Plants at- 

 tacked die suddenly, the leaves and fruit withering up in a day or 

 two and remaining on the vines. 



No remedy is known for this root-rot of the grape. Soil upon 

 which other plants have died with the same disease should be care- 

 fully avoided in planting vines. 



Shelling, The shelling or dropping of grapes from the bunches 

 before maturity may be due to various causes. In some localities 

 in New York and Pennsylvania this trouble is rather serious. The 

 cases which the Department has had an opportunity to study have 

 been found to be due mostly to an imperfectly known fungous dis 

 ease* which appears to be induced chiefly by improper pruning and 

 training. Allowing the vines to produce too heavy crops is also 

 likely to increase this trouble. (F. B. 284.) 



Stem Cankers. Stem cankers of the grape are rather frequent. 

 Many of these are due to injury caused by freezing by which dead 

 spots are produced and in the process of healing these injuries be- 

 come surrounded by excessive growth and enlargements. In some 

 instances the enlargements obtained a diameter of two or three times 

 the size of the stem. The preventive measures are the same as for 

 any freezing injury, viz., drainage and prevention of excessive late 

 growth. (Ohio E. S. B. 214.) 



TROPICAL AND SUB-TROPICAL FRUIT DISEASES. 



FIG DISEASES. 



The Fig Anthracnose. This is a disease of the fig fruit causing 

 it to rot and to become worthless. It is caused by the same fungus 

 which produces the very destructive bitter rot of apples in most of 

 the apple regions namely, Glomerella fructigena. This fungus 

 has been known upon apples, grapes, and some other fruits for many 

 years, but its presence upon figs seems not to have been noticed until 

 recent years. 



