202 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



in^ of lo.sistant sorts, so as to avoid tl»e expenses of spraying, which 

 are unusually ^reat, owing to the height of the trees and the fre- 

 quency of rains, in much of the pecan-growing territory. Fertilizer 

 experiments have been continued in the olToi't to find out t'leir effects 

 in controlling pecan diseases, such as the droj) of pecans and the 

 failure of (he nuts to fill. 



Western physioi^gical troubles. — The extreme heat of the sea- 

 son of 1910 and other conditions not fully determined developed 

 injury to the foliage and fruit, and in some places to the trees, in some 

 of the irrigated orchards of the Rocky Mountain region. Some time 

 was spent in studying this trouble, the disease was identified, and 

 the conclusion reached that the injury is mainly due to the soil, 

 though influenced by climatic conditions. 



The chlorotic group of diseases, including the apple rosette, ap- 

 pears to be increasing in severity over many of the irrigated orch- 

 ards of the Rocky Mountain region and the Pacific Northwest. At- 

 tention has been given to this trouble but no treatment has yet been 

 discovered. 



Citrus diseases. — Laboratory work on citrus diseases has been 

 continued. Urgent requests to take up numerous problems in citrus 

 pathology have come from the citrus-growing districts. These prob- 

 lems relate to such diseases as the wither-tip and gum disease in 

 California and Florida and the orange blight in Florida. The bu- 

 reau, however, has not been prepared to give this work the attention 

 it deserves. 



Fruit rots. — Laboratory studies on the fungous fruit rots have 

 been begun during the past year. Little work on this important 

 group of diseases has been undertaken by the bureau up to date. 



Grape diseases. — The work on grape diseases has been contin'ied 

 in Michigan, New Jersey, and North Carolina. The very excellent 

 results in the control of black-rot in Michigan have been repeated, 

 and the grape growers there are practically all practicing successful 

 methods of spraying. The work on grape anthracnose in Michigan 

 has been remarkably successful, and there seems little doubt that 

 this very destructive disease can be almost entirely prevented by a 

 combination of dormant and summer spraying. The various forms 

 of lime-sulphur have proved very unsatisfactory as substitutes for 

 Bordeaux mixture for grape diseases. 



Cranberry diseases. — Several series of spraying experiments for 

 cranberry diseases are being conducted in Massachusetts in coopera- 

 tion with the State experiment station. In New Jersey attention has 

 been directed especially to the development and perfection of spray- 

 ing apparatus adapted to the requirements of cranberry growers. In- 

 vestigations of the cranberry gall disease, which has occurred again 

 this season, and also of several obscure diseases which have been 

 found in Massachusetts, are also being made. 



Miscellaneous diseases of small fruits. — Several diseases of 

 small fruits are under laboratory and field investigation, and the life 

 histories of a number of the organisms causing these diseases have 

 been worked out. The details are being prepared for publication. 

 The studies of the life histories of various kinds of anthracnose have 

 been continued, and the results are nearly ready for publication. 



