576 INSECTS AFFECTING VEGETATION 



contained in a fertilizer, and these are the only points covered by 

 the manufacturers' guarantee. 



It has, however, long been known that the source of each of the 

 above elements was a matter of importance. The nitrogen varies in 

 its effects according as it is derived from nitrate of soda, sulfate of 

 ammonia, cotton-seed meal, fish scrap, dried blood, etc. Phosphoric 

 acid is usually from acid phosphate, but may be from bone, or 

 Thomas slag. Potash may be in the form of sulfate, chloride or 

 carbonate, or from still other sources. (Vir. Truck E. S. B. 1.) 



DISEASES OF GRAIN AND FORAGE. 



ALFALFA LUCERN. 



Anthracnose. Two new anthracnoses have been discovered at- 

 tacking alfalfa; the first of these, Colletotrichum tnjolii, so far as 

 known occurring exclusively on plants of this family, the other, 

 Colletotrichum, occurring only on alfalfa in northern Ohio. The 

 first one, which we may call clover anthracnose, was discovered in 

 Tennessee and has appeared upon alfalfa as well as red clover in the 

 southern portion of Ohio. It is less prevalent on alfalfa than upon 

 the red clover. Up to this time this disease has not been discovered 

 upon either host in the northern half of the state. The second 

 anthracnose occurred recently upon alfalfa from Sandusky and 

 Carroll counties and has not been described. Both of these dis- 

 eases show as a specific lesion or diseased spot on the stem or leaf- 

 stalk in the advanced stages of attack. Following this the plants wilt 

 or die and are discovered in this way. The disease is too new with 

 us to measure its injuries directly. To the writer it appears less 

 serious than the dodders or the root-rot troubles. 



Bacterial Blight (Yellowing). A bacterial blight of alfalfa, 

 of which the casual organism has not been definitely determined, has 

 been reported from Colorado where it appears to be spreading. In 

 1907 and to a still greater extent in 1908, there was much complaint 

 of general yellowing of leaves of second crop alfalfa in Ohio and 

 adjoining states, even extending to North Carolina. The symptoms 

 were general yellowing of this crop. With brighter, drier weather 

 later the next succeeding crop was of normal color. Bacteria have 

 been found by the assistant botanist in connection with this trouble 

 in specimens from eight localities and from four different counties 

 in Ohio during 1908 and 1909. 



Downy Mildew. The downy mildew fungus (Peronospora 

 trifoliorum) has occurred in Colorado, and is very liable to occur in 

 other states. No suggestions can yet be made as to its prevention. 



Leaf-Spot Fungus. This forage plant is grown in parts of 

 Ohio. It is attacked by the leaf-spot fungus (Pseudopezia medi- 

 caginis) which is found upon both leaves and stem. The small dark 

 spots produced by it are easily seen. In attempts to produce alfalfa 

 seed at this station, the fungus has stripped the leaves and seed 

 capsules before maturity. It is very likely to prevent success in 

 growing this seed in Ohio, though it is much less injurious to the 

 forage crop proper because of cutting at short intervals. 



