218 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



Field experiments with pecan rosette have continued to demand 

 most of tlie time of the pecan-disease e.\i)erts. Some interesting; and 

 favorable results have been obtained in tiie control of this deasese by 

 the application of humus-forniin<; organic matter. Each year of 

 these field experiments marks a step in advance in the control of 

 this disease. Spraying and dusting expei'iments for pecan scab have 

 been continueil, and favorable results in disease control were secured 

 last fall and are reported for this season. 



CITRUS SCAB. 



The spraying experiments for citrus-scab control have shown the 

 marked superiorit}'' of a combined spra}' of Bordeaux mixture and 

 oil enudsion. This combination prevents the increase of scale insects 

 tiuit usually follows tlie use of Bordeaux mixture in citrus groves, 

 does not lessen appreciably the fungicidal efficiency of the Bordeaux 

 mixture, and reduces the number of spraying operations required in 

 the routine control of fungi and insects in the grove. The results of 

 studies of the life histor}- of the causal organism and the conditions 

 influencing infection are almost ready for publication. 



MELANOSE AND STEM-END KOT. 



The stem-end manifestation of PJiomopsis citri attack has been un- 

 usuall}' severe during 1920, although less than in 1919. Satisfactory 

 progress has been made in the study of the relationships of the fungus 

 to each trouble, contributing factors in infection, etc. For the first 

 time promising results have been obtained in the control of melanose 

 by spraying, and the success seems fundamentally due to the ability 

 to use Bordeaux mixture freely in Florida citrus groves by the admix- 

 ture of oil emulsion. 



CITRUS TEAR-STAIN. 



Further evidence confirms the conclusion that tear-stain of citrus 

 fruits prevalent in Florida and commonly ascribed to C olletotrichum 

 gloeosyorioides is not caused b}^ any fungus, but is most probably a 

 type of rust-mite injury. The entire practicability of controlling it 

 by ordinary methods of rust-mite treatment has been determined. A 

 final report on this project has been prepared for publication. 



WITHER-TIP OF LIME. 



Life-history studies of the causal organism of the wither-tip of 

 limes have been continued, and the attempt is being made through 

 selection and breeding to develop a resistant lime of the general 

 West Indies type. 



CRANBERRY DISEASES. 



Studies have been continued of the various methods of harvesting 

 and handling cranberries and on the keeping and carrying quality 

 of the fruit. The practice of raking fruit from the water, as is 

 frequently done in Wisconsin, may or may not be profitable, depend- 

 ing upon the conditions under which the fruit is grown, the variety, 

 and the diseases present, as well as upon conditions for rapid 



