1919.] PUBLIC DOCUMENT — No. 31. 25 a 



the onion crop. Those onions which went into storage prior 

 to that time have for the most part kept in prime condition. 

 In many fields, however, the crop was pulled and allowed to 

 remain on the ground throughout the rainy period, and during, 

 that time a serious bacterial rot was started, which since has 

 ruined large quantities of onions in storehouses. Neck rot, 

 which ordinarily is common among stored onions, has been 

 negligible in amount this year. Owing to this condition the 

 department's investigation of onion diseases has been confined, 

 for the most part, to this bacterial rot and studies in the coatrol 

 of smut. Field plots are planned for the season of 1919. 



It is worthy of note that serious outbreaks of ''white pickle," 

 a form of cucumber mosaic which causes stunting and de- 

 formity of cucumber fruit, occurred at several points, both 

 out of doors and in greenhouses. This is a physiological disease 

 related to mosaic of tobacco, potato, tomato and other plants. 

 Knowledge of the disease is incomplete, but it has been shown 

 that it may be transmitted through the agency of plant lice 

 and possibly other insects, and that control measures must 

 include insect eradication and destruction of diseased plants. 

 The disease will be kept under observation, and it may become 

 worth while to institute investigations of its nature and control. 



In addition to project work, many activities have engaged 

 the attention of the department staff. The usual amount of 

 seed work, examination and diagnosis of diseased plant ma- 

 terials, identification of weeds and other plants, and corre- 

 spondence dealing with a variety of subjects are some of the 

 things which demanded a goodly share of time. The appoint- 

 ment of an extension plant pathologist, noted in our last 

 annual report, has relieved the writer of a large part of the 

 responsibility involved in correspondence concerning plant 

 diseases, and at the same time this feature of our work has 

 greatly increased. The plant disease survey has required more 

 attention than in past years, and several members of the staff 

 were appointed assistant collaborators in this work with the 

 Bureau of Plant Industry. 



The work of overhauling and cataloguing the mycological 

 collection has been completed by the curator, and now awaits 

 the purchase of additional steel cases in order that the work 



