ANNUAL REPORT, 1933 19 



Vegetable Seed Treatments. (E. F. Guba, Waltham.) Organic mercury 

 and red oxide of copper powders consistently gave the best results in controlling 

 damping-oflf in the greenhouse, and the difference in the merit of the two materials 

 was in general in favor of red copper oxide. Monohydrated copper sulfate 

 in general gave comparatively poor results, but even these were better than with 

 no treatments. In other experiments, dry powdered basic copper sulfates, copper 

 acetates, and copper carbonates gave excellent results. In two extensive field 

 experiments the best stand and growth were obtained from seed treatments with 

 organic mercury and red oxide of copper, while monohydrated copper sulfate 

 proved of little or no value. Further comparative tests of the most promising 

 powders are planned, to determine the best dry seed treatment for each field- 

 sown vegetable crop. 



Injury was noted from soaking seeds of tomato, squash, cabbage, and cauli- 

 flower in mercuric bichloride solution at recommended intervals and dilutions, 

 while corn and cucumber were not affected. Organic mercury soaks were safe. 

 In view of the excellent stands resulting from seedbed treatments with oxy- 

 methylene dusts under glass, and from dry seed treatments in the field, the 

 practice of soaking seeds in liquid mercury disinfectants as an additional means 

 of controlling certain crop diseases in the field is open to question. 



Causes and Control of Decay of Winter Squash in Storage. (E. F. Guba, 

 Waltham.) So far, work has been concerned with visitations to squash storages 

 and the culturing of material for study. The following organisms have been 

 isolated from decajed squash: Rhizopus sp., Penicillium sp., Acrostalagmus 

 cinnabarinus Cda., Hormodendron dados poriotdes E. & H., Mycosphaerella cit- 

 ndlina (C. O. Smith) Gross, two undetermined species of Gloeosporium, two unde- 

 termined species of bacteria, three undetermined species of Fusarium, and 

 Bacillus tracheiphilus E. F. S. The biology of most of these species has been 

 established and the different types of decay resulting from artificial inoculation 

 described. 



Complete surface disinfection of Blue Hubbard squash at a temperature range 

 of 60° to 70° F. required 9 liquid ounces of formaldehyde and 6 ounces of potassium 

 permanganate by weight to 1500 cubic feet of space, when the gas was confined 

 24 hours. Shorter exposures were ineffective, and the merit of weaker doses at 

 longer exposures was not determined. 



Strawberry Gold Leaf. (E. F. Guba, Waltham.) The seriousness of this 

 non-infectious chlorotic disease of the strawberry is expressed in inferior plant 

 making and increased susceptibility to winter injury — both of which greatly 

 diminish the yield and quality of berries. Two comparative plots with the same 

 number of mother plants had a difference in yield of 4349 boxes of berries per 

 acre in favor of yellows-free stock. No spread occurred from diseased to healthy 

 rows of plants growing adjacent to each other in the field. Propagation of these 

 plants is being continued for further evidence. Vertical unions of the root crown 

 of diseased and disease-free stock did not result in spread of the disease to the 

 healthy half, or to its daughter plants in the first cropping season. 



Diseases of Herbaceous Ornamental Plants Caused by Soil-Infesting Fungi. 



(W. L. Doran.) This project was begun with work on the effect of certain soil 

 treatments on damping-off and on growth of plants. Except as otherwise 

 indicated, treatments were applied to soil immediately before seeding. The 

 number of grams of material applied per square foot of soil surface and thoroughly 

 mixed with soil is indicated. Soil was 3 inches deep in flats. Most of the damp- 



