Jan. 1922] annual report. 13 



of banana pulp and sodium arsenite, gave inconclusive results. In cage 

 experiments the previous year it was noted that the adult flies were attrac- 

 ted to banana, either sliced or made into pulp. Following this clue a more 

 extended study was carried out. As in the previous year flies were attrac- 

 ted to the banana pulp, including both the check, where unpoisoned banana 

 pulp was used, and the treated, where sodium arsenite was added to the 

 pulp. Some flies were poisoned and their dead bodies recovered. But 

 apparently the treatment was not effective enough to reduce egg-laying in 

 marked degree, especially as the season progressed. During the first three 

 days after treatment the number of eggs recovered from 125 plants in the 

 check plots was 25, as compared with 3 eggs recovered from 125 plants in the 

 treated plot. As the season advanced, however, no difference could be dis- 

 cerned from counts of eggs. 



Fruit Bud Formation. 



The study of the underlying causes of fruit bud formation, which has 

 been in progress with Baldwin apples at the Woodman Orchard since 190S, 

 was maintained last year along the usual lines by G. F. Potter and S. W. 

 Wentworth (Horticultme) . The plots receiving fertilizer in addition to 

 cultivation and cover crops continued to show greatest growth as measured 

 by diameter of trimk and annual twig growth. From the fertUized plots 

 the crop for the 1920 season was on the average about 50% larger than from 

 the unfertilized plots receiving the same cultural treatments. It is believed 

 that the fertilized trees are also bearing more regularly, but it will take data 

 from several seasons to establish this fact. 



The probable error for the average yield and growth per tree in each plot 

 has been computed, and, as might be expected, has been found to be high 

 in relation to the yield in the three plots having a small number of trees. 

 These plots are Number 1 in sod and Numbers 2 and 3, tilled in alternate 

 years. This corroborates the opinion expressed in previous publications 

 that the anomalous difference in yield between Plots 2 and 3, which receive 

 the same treatment, is merely due to chance. 



In addition to the usual work in this project the chemical phases involved 

 in the study have been actively prosecuted in co-operation with Mr. Kray- 

 bill (Agricultural Chemistry). 



Effects of Light upon Fruit Production. The results of the shading work 

 conducted by J. H. Gourley (Horticulture) have now been published in the 

 Station technical series. Chemical analyses have been made by Mr. Kray- 

 bill of samples taken from the growth of shaded and unshaded trees during 

 the past two years, and show the former to be higher in moistm'e and total 

 nitrogen, and lower in free reducing sugars and starch. It is evident that 

 the factor of greatest importance which is influenced by shading is the amovmt 

 of carbohydrates synthesized by the leaves and stored in the fruit spurs. 

 We know practically nothing about this process in normal trees. An ex- 

 tensive investigation has therefore been made during the past year of bear- 

 ing and non-bearing fruit spurs from trees in sod and trees under condi- 

 tions of good cultm-e and high fertility. Duplicate samples were taken at 



