ANNUAL REPORT, 1939 25 



slightly under different humidity and temperature conditions. In the 1937-38 

 storage season shrinkage was reduced from 9.2 percent to 7.3 percent when 

 average mean relative humidities of 62 percent and 84 percent and average mean 

 temperatures of 57.3° F. and 45° F. respectively were contrasted; but under low 

 temperature and high humidity the loss from decay was approximately doubled. 

 Decay under low temperature and high relative humidity storage conditions rises 

 rapidly after the first of January. 



Factors Affecting Yield of Onions and their Shrinkage in Storage. (C. J. 



Gilgut and W. G. Colby. Cooperative with Agronomy.) Twenty-five lots of 

 onion sets gathered from a number of Connecticut Valley onion growers were 

 grown under the same conditions on a plot of typical onion land to determine the 

 effect on yield and shrinkage in storage of (1) variety and source of seed sets, 

 (2) stage of maturity at time of harvest, and (3) methods of harvesting, curing, 

 and storing. The following conclusions are based on observations made during 

 the growing season and on experimental data thus far collected. 



Although, at the time of planting, no visible dift'erence in the quality and 

 uniformity of the different lots of sets on trial was apparent, there was con- 

 siderable variation in performance. Locally grown Japanese seed sets grew more 

 vigorously throughout the season and significantly outyielded Japanese seed 

 sets shipped into Massachusetts. 



Onions harvested after nearly all tops had broken over yielded 30 percent more 

 than onions harvested ten days earlier when approximately 75 percent of the 

 tops were down. In the case of the Connecticut globe type seed sets, later harvest- 

 ing resulted not only in greatly increased yields, but also in improved quality 

 because of fewer small, objectionable bottle-neck bulbs. 



Shrinkage resulting from disease after 75 days in storage ranged from 2 percent 

 in some varieties to as much as 30 percent in others. The average for all varieties 

 indicates that onions harvested when the tops were completely down developed 

 15 percent more disease in storage than onions harvested 10 days earlier, but this 

 was more than offset by the increased yield. Onions which remained in burlap 

 bags in the field until October 1 before being moved into storage showed approx- 

 imately 5 percent greater loss from disease than onions placed in storage a few 

 days after harvest. 



The bulk of loss due to disease was caused by bacterial soft rot and Fusarium 

 bottom rot. At the end of 75 days in storage, the former accounted for 46 percent 

 of the decayed onions; the latter for 48 percent. Bacterial soft rot was more prev- 

 alent in the early part of the storage period than other types of decay, but de- 

 creased in amount as the storage period progressed. Fusarium bottom rot, on the 

 contrary, was less prevalent during the earlier part of the storage period than 

 during the latter. 



It is interesting to note that while Botrytis neck rot is said to be one of the 

 chief causes of lo&s in storage, thus far this season only one onion out of 2J^ tons 

 examined was affected by this disease. 



Miscellaneous Tests and Experiments. (E. F.Guba and C. J. Gilgut, VValtham.) 

 1. Apple Scab Control. The apple spraying experiments were intended to 

 determine the relation of sulfur particle size to scab control. The wettable sulfurs 

 were all used on the same sulfur basis by weight. 



Six applications were made. All treatments except that at the pink bud stage 

 were combined with lead arsenate, and for the curculio and maggot sprays 4 

 pounds of lead to 100 gallons of spray were used. There were no significant 

 contrasts in the control of scab in spite of differences in sulfur particle size. Where 

 lime-sulfur was used in the precover sprays the usual injury, dwarfing and scant 

 foliage, developed. The excellent control of scab with insignificant amounts of 



