ANNUAL REPORT, 1938 91 



northern limit is approached. Dropping varies from year to year, from orchard 

 to orchard, and from tree to tree in the same orchard. The problem seems to have 

 become more acute in recent years. 



Dropping was more severe with trees grown under a high state of fertility, and 

 significant correlations were found between yield and percentage drop in most 

 cases. Rootstock effect upon dropping severity was evident. I'his may help to 

 explain wide variations among individual trees in an orchard. 



Besides the secondary influence of wind, high maximum temperatures of even 

 short duration in the harvest period hastened drop. 



Seed number was positively correlated with time of drop. The many-seeded 

 fruits not only hung better but were larger than those with few or no seeds. 

 Seed number varied from to 21 per fruit. Spur diameter, spur position, and leaf 

 area were not found to exert significant influence, except that severe late-season 

 defoliation caused increased abscission. Some evidence was found that long- 

 stemmed apples dropped before those with shorter stems. 



There are indications that strains may differ significantly in preharvest dropping 

 behavior. At the present time it seems that this premise offers the most practical 

 approach to the solution of the problem. 



Sun Coloring of Apples. (O. C. Roberts.) In September 1937, experiments 

 were started to study the effect of exposing poorly colored Mcintosh apples to 

 sunlight after harvest. Results of this initial experiment were reported in the 

 Experiment Station report for 1937. 



The experiment was continued during the summer of 1938. A wooden frame 

 covered with two layers of 25 x 25 mesh cheesecloth was used. The experiment 

 consists of four parts: (1) How early in the season color may be obtained by 

 artificial methods; (2) the relation of sun scald to color development; (3) the 

 number of hours of sunshine necessary to produce satisfactory color on normally 

 uncolored fruit at harvest time; and (4) the effect of sun coloring on the keeping 

 quality of the fruit. While no definite conclusions can be drawn from this experi- 

 ment for the past season, there are a few trends that are worthy of note. 



There is a tendency for apples picked prematurely to scald before acquiring 

 satisfactory color. This tendency decreases as the apples approach maturity. 



The time of exposure necessary to produce satisfactory color decreases as the 

 apples approach maturity. When apples are fully mature, 30 hours of bright 

 sunshine are ample to produce satisfactory color. 



Sufficient color can be produced to admit apples to the fancy grade without 

 turning them during exposure. Two layers of cheesecloth to provide shade during 

 the coloring period appear adequate for the prevention of sun scald. 



Exposure to conditions necessary for coloring does not seriously impair the 

 keeping quality of apples when they are stored at 32° F. as soon as the desired 

 color is obtained. 



DEPARTMENT OF POULTRY HUSBANDRY 

 R. T, Parkhurst in Charge 



Broodiness in Poultry. (F. A. Hays.) There are three major objects in this 

 project: (1) To secure adequate data on the inheritance of degrees of broodiness, 

 (2) to study the problem of deferred broodiness, (3) to establish a genetically 

 non-broody line of Rhode Island Reds. 



The generation hatched in 1937 and completing the laying year in 1938 was 

 sired bv two males that were 24 months old. These two males had the same sire 



