64 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



Studios are also being made of the bacterial and fungous content of 

 spoiled maize; the inter-relation of crown-gall organisms; the new 

 and destructive Grand Rapids tomato disease; banana diseases, 

 especially a very destructive blight of the whole plant, and of all sorts 

 of bacterial diseases of plants. 



Fruit-disease investigations. — The new methods of spraying 

 with sulphur compounds worked out by the pathologists of the 

 Department have been widely adopted by apple growers. The 

 investigations have shown that fine fruit can be produced and pro- 

 tection secured against fungous diseases without the injurious effects 

 resulting from the use of copper compounds. 



Bordeaux mixture is still probably the most effective all-round 

 fungicide, but in the spraying of the apple it has to take second place, 

 to be used only for special purposes, such as late treatment for bitter- 

 rot. Special attention has been given to experimental work in per- 

 fecting the method of using the new sulphur sprays for the fruit-spot 

 and leaf diseases, and in cooperation with the Bureau of Entomology 

 studies have been made of the combined sprays of the sulphur and 

 arsenic compounds, with which both diseases and insects were treated 

 at the same time. In most cases fruit growers who have used the 

 new sprays have secured fine crops of the best apples they have ever 

 grown. The new types of spray injuries which resulted are unimpor- 

 tant and are probably avoidable. 



The fruit-spot and leaf disease known as cedar rust or orange rust 

 of the apple has been increasing in prevalence in the Blue Ridge and 

 Allegheny Mountain district from Pennsylvania to Tennessee during 

 the last few years. This past season the worst outbreak of this 

 malady ever known has occurred. It has attacked mainly the York 

 Imperial, but the Yellow Newtown and some other varieties have been 

 affected. The fungus has its alternate generation on the red cedar. 

 Previous investigations by pathologists have shown that the immedi- 

 ate proximity of cedars greatly favors the disease. Recommenda- 

 tions made in previous years to cut down cedars from the vicinity of 

 commercial apple orchards have not been taken very seriously. 

 During the present season, however, many cedars in dangerous prox- 

 imity to orchards have been removed. The disease has not hereto- 

 fore proved amenable to spraying, but it was shown during the last 

 season that spraying wdll very largely prevent it if applications are 

 made just before the period of general infection. 



For two years attention has been called to the discovery of self- 

 boiled lime-sulphur as a fungicide which can be used in the summer 

 spraying of the peach for brown-rot and scab. In 1909 this spray 

 was successfully used in combination with arsenate of lead. The 

 preliminary experiments of last season w^ere redemonstrated on a 

 large scale in Georgia, Virginia, and West Virginia, resulting in a com- 



