24 MASS. EXPERIMENT STATION BULLETIN 315 



of one week. Resin 1:125 similarly applied was slightly less effective, and there 

 was very poor control with a 0.35 percent solution of soap. The only one of these 

 materials by which the growth of plants was significantly retarded was Bordeaux 

 mixture 4:4:50. 



Forty strains of lettuce^ were grown in the greenhouse and inoculated with 

 B. lactucae when they were one, two, and three weeks old. Only the following 

 strains seemed markedly resistant to infection: Blonde Pionnel (Clause), Merveille 

 d'Hiver (Clause), Batavia Beau Jolaise (Clause), Batavia White Paris (Bulleri), 

 and May Wonder (Benary). 



Eggplant Wilt. (E. F. Guba, W T altham.) Study has substantiated recent pub- 

 lished reports that seed carriage of the causal fungus ( Verticillium albo-atrum 

 R. & B.) may occur. Infected seed was obtainable only from fruit showing the 

 characteristic brownish discoloration of the fibrovascular bundles in the blossom 

 or distal half. A water-bath temperature of 117.5°F. for 30 minutes was lethal 

 to the fungus, while 115° for the same period was not lethal. Preliminary tests 

 indicate that the former hot-water treatment is not injurious to eggplant seed. 



Control of Greenhouse Vegetable Diseases. (E. F. Guba, Waltham.) The 

 Bewley tomato hybrids which were crossed with Norduke (Mass. Agr. Expt. 

 Sta. Bui. 305, p. 18) show only partial resistance to the leaf-mold fungus Clado- 

 sporium fulvum Cke. This partial resistance is considered of some value under 

 conditions permitting only light infection and slow development of the disease. 

 Under conditions extremely favorable for infection, this type of resistance is in- 

 sufficient to make these hybrids suitable for further consideration. It is evident 

 that limited or partial resistance to the disease is all that may be expected from 

 hybridizing varieties within the species Lycopersicon esculentum Mill. The 

 hybrids resulting from crossing L. pimpinellifolium Mill., a species of tomato 

 immune to the fungus, with three varieties of L. esculentum showed in the Fj,a 

 homozygous condition for all characters and immunity; and in the F 2 ,a hetero- 

 zygous condition for all characters. Immunity appeared to exist in the ratio of 

 3:1. Selections from immune individuals are now being grown (F 3 generation) 

 to establish resistant lines and to back cross with the parent varieties of L. esculen- 

 tum, i. e., Belmont, Break O'Day, and Success, for desirable fruit size. 



Vegetable Seed Treatments. (E. F. Guba, Waltham.) In a series of trials to 

 determine the value of dry chemical seed treatments on stand of seedlings, the 

 best results were obtained with Cuprocide, Cure-Damp, copper carbonate 18 

 per cent and 50 percent, zinc oxide, and basic copper acetate. Semesan was gen- 

 erally less efficient. Red oxide compound, Corona P D 7, and basic copper sulfate 

 52 percent, showed even poorer results. Sanoseed was distinctly unfavorable. 



In these tests the dry powders were added to the seed in excess and the surplus 

 removed by screening before sowing. 



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

 Waltham.) Further study has sought to find an efficient, practical method of 

 disinfecting squash prior to storage. Formaldehyde gas generated from 40 per- 

 cent formaldehyde solution, chlorine from bleaching powder, and sulfur dioxide 

 from burning sulfur were considered. Burning of brimstone at the rate of 5 

 pounds to 10,000 cubic feet of storage, while possessing excellent disinfecting 

 properties, was injurious to squash. Further work with sulfur dioxide is in prog- 

 ress. Chlorine generated from bleaching powder with hydrochloric acid in in- 



'Furnishcd by Dr. O. H. Pearson of Eastern States Farmers' Exchange. 



