REPORT OF THE SECRETARY, 57 



Apple spraying experiments and demonstrations were conducted 

 in several widely separated districts, and it was again shown that 

 lime-sulphur properly diluted is a more satisfactory fungicide for 

 certain apple diseases than Bordeaux mixture. However, owing to 

 the severe weather conditions of the season, the combination of lime- 

 sulphur and arsenate of lead caused considerable burning of the 

 fruit in a few orchards, but this trouble was not so serious as to 

 discourage the use of this spray. 



The grape anthracnose is very destructive to both fruit and vine. 

 Certain varieties in some localities are attacked every year by this 

 disease. The department has demonstrated the past season that this 

 malady can be satisfactorily controlled by proper spraying of the 

 vines while in a dormant condition. Further confirmation of pre- 

 vious results in the control of black-rot of the grape has also been 

 obtained. Very promising results have been secured in controlling 

 the anthracnose of the cranberry, which has been found to be a preva- 

 lent cause of loss in some cranberry districts. Considerable progress 

 has also been made in the study and control of other small-fruit 

 diseases. 



DISEASES OF COTTON AND TRUCK CROPS. 



Diseases of the potato have assumed unusual prominence through- 

 out the country during the past season. Physiological disturbances 

 have combined with several parasitic diseases in bringing about a 

 general reduction of the crop. Blackleg and both the early and late 

 blights have been sufficiently severe to emphasize the importance of 

 a more general adoption of preventive treatment by growers, but by 

 far the most serious damage has been caused by potato wilt, a disease 

 which usually assumes an inconspicuous form, causing premature 

 ripening followed by dry-rot in storage. The unusually dry season, 

 which retarded the early growth of the plants, was very favorable 

 for the development of wilt. The resulting epidemic has served to 

 emphasize the wide distribution of this disease and has given it a new 

 importance. Studies are under way which should lead to a more 

 thorough knowledge of the causes and the means of control. 



Investigations on the diseases of sweet potatoes have been inaugu- 

 rated and substantial progress made. The causes of the more im- 

 portant troubles are now known, some of them for the first time,, 

 and means of control are being studied with encouraging results. 



The disease-resistant varieties of cotton, cowpea, and watermelon 

 which the department has developed are being brought into more 

 general trial by thoroughly organized cooperative arrangements with 

 growers in the infested sections. This organization is being extended 

 as rapidly as the nature of the problem and the facilities of the 

 department will permit. 



