FLORIDA. 119 



scaly bark disease included field and laboratory operations and co- 

 operative experiments on 200 trees, and was about completed for the 

 final report, a preliminary report having been nuide a j^ear ago. 



The plant physiological investigations were carried on from the 

 standpoint of nutrition and malnutrition. The results of the nutri- 

 tion studies gave evidence of the toxicity of nitrate of soda to the 

 citrus tree when applied in maximum amounts, and of the counter- 

 action of this toxicity by the use of acid phosphate. The malnutrition 

 studies included the citrus diseases known as melanose, die-back, and 

 yelloAv spotting. About 2,500 microscopic slides of healthy and dis- 

 eased tissue were prejDared and studied in part. Chlorosis of cassava 

 was also investigated by this laboratory. Results indicate the dis- 

 ease to be physiological, brought on by certain unfavorable soil con- 

 ditions, and that it may be prevented by planting upon a rich soil to 

 insure a more favorable grow^th. 



Work on the w^hite-fly project was continued. Spraying experi- 

 ments showed that the fly was most readily destroyed by the use of 

 weak solutions at an early stage in its life history. Experiments were 

 made on a large scale by spraying and applying fungi in orchards for 

 the purpose of determining to what extent the insect may be con- 

 trolled by the use of fungi which attack it. It was found that spring 

 and fall spraying is more effective than winter spraying, and that 

 the use of the fungi costs much less than the application of insecti- 

 cides. In the hottest weather, however, spraying with insecticides 

 was more effective. In the pupal stage the insect Avas apparently 

 immune to fungus attack. The use of laundry-soap solutions was 

 found effective against the fly. A second species of white fly was 

 distinguished and additional food plants of the insect were dis- 

 covered. 



Work in plant breeding was begun as a new project. This new 

 work is carried on with the velvet l)ean and its allies and with corn. 



The work carried on with the Hatch fund was largely along lines 

 of animal husbandry and agronomy. Feeding experiments were 

 made for beef and milk production. In feeding for beef, a ration 

 consisting of 8 pounds of corn, 10 pounds of cottonseed hulls, and 12 

 pounds of velvet beans in the pod gave an average daily gain of 2.92 

 pounds per head for a period of 8-1 days at a cost of 7|- cents per 

 pound of gain. As compared with this result, a ration of 6| pounds 

 of cottonseed meal and 25 pounds of cottonseed hulls gave a daily 

 average gain of 1.85 pounds at a cost of 12 cents; one of 10.5 pounds 

 of corn, 3.75 pounds of cottonseed meal, and 13.5 pounds of crab- 

 grass hay, an average daily gain of 2.68 pounds at a cost of 9 cents; 

 and one of 6 pounds of corn, 5 pounds of cottonseed meal, 20 pounds 

 of sorghum silage, and 14 pounds of cottonseed hulls, an average 

 daily gain of 2.68 pounds at a cost of 10.6 cents per pound of gain. 



