12 MASS. EXPERIMENT STATION BULLETIN 441 



seeding when the seeding operation followed immediately after tilling, liming, 

 and fertilizing. If seeding was delayed for several weeks, little difficulty was ex- 

 perienced. Apparently, therefore, the late summer seedings were more success- 

 ful, not only because weather conditions were more favorable, but also because a 

 period of time had elapsed between tilling, liming and fertilizing, and seeding. 

 In bringing under cultivation land which has long been idle, farmers are advised 

 to apply lime and fertilizing materials some weeks ahead of seeding or planting. 



Red Clover Variety Trials. (Wm. G. Colby.) This project, carried on in co- 

 operation with the U. S. Department of Agriculture Bureau of Plant Industry, 

 is concerned with the resistance of some of the newer strains of red clover to 

 certain diseases. Northern anthracnose (caused by Kabatiella caulivora), a 

 disease which is becoming increasingly serious in other sections of the country, 

 was prevalent on some of the more susceptible varieties included in this year's 

 test. The variety Midland, for example, was seriously damaged. It remains to 

 be seen whether or not this disease will become a serious hazard to red clover in 

 Massachusetts. It may be that weather conditions this year were peculiarly 

 favorable for its development. 



Trials with Sorghum and Sudan Grass Strains. (Wm. G. Colby.) Notwith- 

 standing the superior performance of a well-established, well-managed Ladino 

 clover-brome grass pasture during July and August, the need for additional 

 grazing is frequently felt, particularly during dry, hot seasons. One of the best 

 crops available for providing supplementary grazing at this time is sudan grass or 

 possibly sweet sorghum. Both produce heavy' crops of palatable nutritious feed. 

 If a reasonable amount of care is exercised in seedbed preparation, fertilizing, and 

 seeding, crop failures are rare. Thus far, however, dairymen have been cautious 

 about growing either of these species largely because of the possible danger of 

 hydrocyanic acid poisoning. 



Last season several strains of sudan grass and one of sweet sorghum were 

 grown. In addition to obtaining yield data, tests were made of the cyanide con- 

 tent of the herbage at two growth stages. The Rancher strain of sweet sorghum 

 was obtained from South Dakota where it was bred for low hydrocyanic acid 

 content. 



Samples were first taken for hj'drocyanic acid determination on July 22 when 

 most strains were in full head. All plots were then cut, the hay removed and an 

 application of ammonium nitrate made to supply elemental nitrogen at the rate 

 of 65 pounds to the acre. 



Samples for a second test were taken on September 12. All chemical deter- 

 minations were made by Professor Emmett Bennett of the Department of 

 Chemistry. 



Although Rancher Sorghum and Tift sudan grass ran considerably higher in 

 hydrocyanic acid content at the first cutting than commercial sudan or sweet 

 sudan, a cow would have had to consume from 50 to 60 pounds of green material 

 at one time of either of these strains before there would have been any danger of 

 poisoning. She would have had to consume 300 pounds of sweet sudan grass 

 before being poisoned. 



All strains ran much higher in hydrocyanic acid at the second cutting, with 

 only small differences between strains. A cow would have had to consume from 

 20 to 25 pounds of green material of the second cutting at one time before danger 

 of poisoning. Heavy fertilization with a nitrogen fertilizer was no doubt an im- 

 portant factor in the production of the relatively high content of hydrocyanic 

 acid of the second cutting. 



It would appear from these results that all of the four strains tested could be 

 grown for midsummer pasture in Massachusetts without serious hazard of causing 

 hydrocyanic poisoning. 



