148 ANNUAL REPOETS OF DEPARTMENT OF AGEICULTUEE. 



alfalfa for the production of a pound of dry matter. Measurements 

 of this kind give promise of being very helpful in the selection of 

 varieties and strains of crop plants suitable for use in semiarid 

 regions where the efficient use of the rainfall or of irrigation water 

 is fundamental to the best agricultural development. 



Physiological studies of parasitic fungi. — Study of the methods 

 by which parasitic organisms affecting fruits and vegetables attack 

 their hosts has shown that in general the parasites make use of stored 

 food products in the plants. Study of the conditions affecting pig- 

 ment production in the group of parasites which includes the chest- 

 nut-blight organism has made it possible to determine by the colors 

 produced whether the forms in question are actively parasitic or 

 merely saprophytic. 



Culture distribution. — In accordance with the policy of the last 

 few years pure cultures of nodule-forming bacteria for inoculating 

 leguminous crops were distributed, cultures for inoculating approxi- 

 mately 214,257 acres of legumes having been distributed during the 

 fiscal year 1915, or three times as many as during the previous fiscal 

 year. This distribution is partly for the purpose of stimulating the 

 use of leguminous plants in planning crop rotations and partly for 

 the purpose of developing the best methods of managing the prepara- 

 tion and distribution of pure cultures. With the recent improve- 

 ments in handling these cultures an efficiency for crop improvement 

 equal to that from the use of old soil has been secured. 



Poisonous-plant investigations. — Investigations of poisonous 

 plants thus far have demonstrated the poisonous nature of Oxytropis 

 lamherti and Astragalus mollissitnus, two of the more serious sources 

 of loss from loco, and of all the larkspurs and of certain species of 

 Zygadenus, or death camas, have been demonstrated. Losses of stock 

 caused by poisonous plants on the ranges were investigated in the 

 Absaroka, Colville, La Sal, Chiricahua, Fremont, Manti, Fish Lake, 

 Fillmore, Kaibab, and Plumas National Forests, and methods of 

 treating poisoned animals were pointed out. 



PLANT-BREEDING INVESTIGATIONS. 



Southern prolific types of corn. — By means of variety tests it 

 has been determined that the " southern prolific " type of corn can be 

 grown advantageously over a much wider territory than it is at pres- 

 ent. In tests conducted in localities whei-e these types are not now 

 generally grown it was found the small-eared prolific types gave 

 larger yields and a greater percentage of sound corn than the large 

 single-eared types commonly grown. Seed of suitable prolific varie- 

 ties has been introduced into a number of localities and the adoption 

 of these varieties is- advocated. 



Breeding methods for corn : Indian and Chinese varieties. — A 

 study of the characters in corn hybrids has shown that they behave 

 in a very different manner from those of many other cultivated 

 plants. With most crops the key to successful breeding is the recog- 

 nition and purification of desirable types. In corn, on the contrary, 

 the variations do not appear as definite types. As a demonstration 

 of the utilization of this knowledge it was possible as a result of only 



