DISEASES INJURIOUS TO FRUITS. 117 



off, frequently when the fruit is quite green, which, consequent- 

 ly, does not ripen. But, besides the loss of fruit from this dis- 

 ease, the wood is often left in a very poor, immature state, and 

 the whole plant so seriously weakened that it will not produce a 

 full crop of fruit for several years. It frequently acts in this 

 manner on the Delaware, while it seldom injures the fruit of 

 that variety. On some other varieties the fruit is more sus- 

 ceptible than the foliage and it produces brown rot of the ber- 

 ries, which may cause severe loss in some season. In this 

 case the first perceptible effect of the disease is when a purp- 

 lish spot appears on the side of the berry. Later, the fruit is 

 covered with a white mould, then it turns brown, and later on 

 becomes soft and wrinkled. 



Remedies. Spraying as recommended for Black Rot. 



Powdery Mildew (Uncinula necator). This mildew forms 

 a superficial, cobweb-like growth on the leaves and new growth, 

 and occasionally on the fruit. The remedies are the same as 

 for Downy Mildew. It is also recommended to spray the vines 

 in the winter with copper sulfate solution to destroy the win- 

 ter spores. Flowers of sulfur has also been used successfully 

 against this disease. 



Preventives of grape diseases. Every effort should be 

 made to Keep fungus diseases from getting a hold of the plant. 

 It has been found that where the vines are closely shut in, so 

 that there is but little circulation of air and the water does not 

 quickly dry off the foliage, or where the soil is wet and cold, 

 the vines are very liable to become diseased. On this account, 

 where a vineyard is subject to such troubles, the first thing 

 to do is to remedy, as far as is practicable, anything that ob- 

 structs free circulation of air through it. If the land is moist 

 and cold it should be underdrained. For brown and black rot 

 of the fruit early bagging of the clusters will be found quite ef- 

 fective. But after these things are done, disease may gain a 

 foothold and cause serious injury to weak varieties; hence 

 spraying may be necessary. Some varieties are uniformly 

 healthy in some locations, while others are very susceptible to 

 disease. Yet these latter are often the most profitable kinds to 

 grow for marketing purposes. 



