DISEASES OF PLANTS. 745 



ing the inspection of imporlcd fruits ujicl plants as well as gtudies on plant 

 diseases. These latter include a study of the fungi and insects affecting vari- 

 ous common crops as well as a numl)er of the tropical crops, the material 

 having been sent to the laboratory for study. 



The predisposition of plants to parasitic diseases, II. T. (iussow il'roc. 

 Assoc. Econ. Biol., 1 (190!)), Xo. J,, pp. iJ<S-/7«).— Attention is called to the 

 fact that overassimilation or improper cultivation of plants tends to make 

 them more subject to disease. The author suggests more attention to plant 

 hygiene, and states that if plants are Ivept under conditions which maintain 

 their healthy growth there will be less predisposition to disease. 



The development of farm crops resistant to disease, W. A. Orton ( U. 8. 

 Dcpt. Agr. Yvurhook 1908. pp. .'/.'> 3-.'/ 6'/. pis. 2). — After calling attention to the 

 need of varieties of farm crops immune to disease, the author discusses the 

 basis of disease resistance, considering the adaptation to environment, specific 

 resistance to parasites, the nature of the resistance, etc.. and describes a number 

 of varieties of cotton, cowpeas, melons, potatoes, clover, wheat, and flax that 

 have been developed by Department and station investigators. 



Studies in diseases of cereals and grasses, A. D. Selby and T. F. Manns 

 (Ohio Sta. Bui. 203, pp. 187-236, pis. 2, figs. 20).— A description is given of a 

 new anthracnose of certain cereals and grasses, and studies are reported on the 

 fungus of wheat scab, which occurs on seed and as a seedling parasite not 

 only on wheat but also on a number of small grains. 



The anthracnose seems to be quite prevalent in Ohio and is believed to be 

 conuuou in neighboring States as well, rye, wheat, oats, emmer, and various 

 grasses being subject to attack. ^Inch of the loss due to the shriveling of grain 

 is attributed to this disease. As a result of a study of affected host plants 

 and the cultivation of the organism, the authors have determined it to be an 

 undescribed species of Colletotrichum, to which the name C. cereale n. sp. is 

 given. 



The fungus is parasitic on the roots, culms, blades, and spikes of rye, and on 

 the roots, culms, and blades of wheat, oats, barley, emmer, orchard grass, 

 timothy, blnegrass, chess, etc. It is said to have caused noteworthy losses in 

 the yields of rye in fields where it prevails. The attacks of the anthracnose 

 are shown by the premature dying of those portions of the spikes above the 

 point of attack, resulting in an almost total loss of grain in these dead portions. 

 On wheat there is no special attack of the wheat head, and the roots are less 

 frequently affected. The basal portions of the stem and the basal leaf sheaths 

 of wheat are conspicuously attacked, and the disease is accompanied by pre- 

 mature whitening and ripening of the plant and much shriveling of the grain. 

 Similar conditions are found on the other host plants enumerated. 



The spores of the fungus readily disseminate the disease through the seed 

 grain, as is shown by the result of centrifuge examinations made of the wasli- 

 ings of suspected grain. Seed treatment with formaldehyde is recommended, 

 as preliminary investigations seem to indicate its efficiency. 



Tlie studies on the wlieat scab have been continued (E. S. R., 11, p. 161), and 

 it is shown that the scab fungus certainly survives as an internal infection in 

 scab-infested kernels of wheat. Pure cultures have been obtained of the fungus 

 by placing externally sterile grains upon agar in Petri dishes. Tliese investi- 

 gations not only demonstrate that the scab fungus survives in the dead wheat 

 kernels, but also in those capable of germination. The fungus is an exceed- 

 ingly active parasite, killing young wheat plants when they are a month or 

 less old. ^ 



The cause of this disease has been attributed to Fusarium roscum and 

 rtihhcrrUa sauhinctii, and infection experiments in the greenhouse and cultin-al 



