28 MASS. EXPERIMENT STATION BULLETIN 388 



merit based on weight of seed) were furnished to the cooperators by the com- 

 mittee. Five repHcaticns of 100 seeds for each treatment and no treatment were 

 counted and planted in randomized blocks. 



With cucumber, there was no significant difference between treatment with 

 0.25 percent red copper oxide, 0.75 percent Semesan, and no treatment. Treat- 

 ments with 2 percent red copper oxide, 2 percent zinc oxide, and 0.2 percent 

 Semesan showed no significant differences with celery; but with lettuce 2 percent 

 red copper oxide and- 2 percent zinc oxide were significantly better, in the order 

 given, than no treatment. With sweet corn, 2 percent red copper oxide, 2 per- 

 cent zinc oxide, and 0.2 percent Semesan Jr. were no better than no treatment. 

 Cabbage was distinctly benefited by 2 percent zinc oxide and 0.2 percent Semesan. 

 From seed treated with hot water and subsequently with chemical dusts, the 

 stands were reduced, yet they were better than stands from seed treated only with 

 hot water. 



The value of a number of dry chemical powders in preventing pre-emergence 

 damping-off and seed decay of lima beans was determined. Spergon-treated 

 seed produced a larger number of seedlings and consequently a greater yield 

 of lima beans than seed receiving anj' other treatment or no treatment. The 

 second best treatment was red copper oxide, which held a slight advantage in 

 number of seedlings and yield over zinc oxide. Semesan was distinctly injuricus 

 to the seedlings, the injury persisted throughout the growing season, and the 

 yield was materially reduced. Although more seedlings grew from seed treated 

 with Semesan than from untreated seed, the total jield from untreated seed was 

 nearly twice that from Semesan -treated seed. 



Effect of Vitamin Bi at Different Soil Temperatures on Gardenia Chlorosis. 



(L. H. Jones.) Gardenia plants became chlorotic at soil temperatures of 55°, 

 60°, and 65° F. The soil was treated weekly with a solution of thiamin chloride 

 (vitamin Bi), one part in ten m-lUon, used at a temperature equal to the soil 

 temperature. The plants were replicated in sufficient containers so that the 

 thiamin chloride could be applied before, at the observable period when, and 

 after chlorosis appeared. There was no noticeable evidence that thiamin chloride 

 at this concentration could prevent chlorosis induced by low soil temperatures 

 or cure a gardenia plant so affected. 



In a later test with chlorotic plants, soil treatment with 100 times the above 

 concentration (1 part in 100,000) did act as a mild remedial measure. New 

 leaves at the unfolding stage were dark green in color, old leaves had the yel- 

 lowing between the veins supplanted with a healthy green color, and basal shoots 

 developed with dark green foliage. Since this effect took place at about the 

 time of the vernal equinox, it appears that this concentration of thiamin chlor-'de 

 hastened what would have occurred normally a short time later. Since the tem- 

 perature of the solution when applied corresponded to the soil temperature, the 

 results must be ascribed to the use of vitamin Bj. 



The Effect of Soil Temperature on Growth. (L. H. Jones and J. W. Hall.) 

 Corn, tomato, and rose were used as indicator plants. When soil temperatures 

 were altered to 55°, 60°, 70°, 80°, and 90° F., plants which were established in 

 the soil at 75° showed marked effects of temperature on development over a 

 period of 78 days. There was poor growth and no flowering of corn, tomato, and 

 rose plants at soil temperatures of 55° and 60°, but at 70°, 80°, and 90°, the plants 

 grew vigorously and flowered. Corn and rose plants did best at 90°, while the 

 tomato, John Baer, apparently was at its optimum environment at a soil tem- 

 perature of 80°. Intcrnode length in corn increased up to a soil temperature of 

 70°, while the internodes of the tomato plant were longest ?t 80°. The air tern- 



