No. 2, September, 1921 J PATHOLOGY 147 



topathological subjects are summarized: (1) Recovery of diseased plants after transplanting 

 to the experiment field; (2) soil sickness; (3) production of sclerotia of Claviceps purpurea 

 in large quantities; (4) ergot of rye in relation to grasses; (5) use of chemicals as fungicides 

 and insecticides; (G) control of celery leaf spot {Sepioria apii) with Bordeaux mixture. — 

 D. Alanasoff. 



937. Rosen, H. R. Further observations on a bacterial root and stalk rot of field com. 

 Phytopathology 11: 71-79. Fig. t-4- 1921. — In continuing work formerly reported [see 

 Bot. Absts. 3, Entry 2742] field observations and inoculations have shown that 17 varieties 

 of field corn and 1 of sweet corn are suscejitible to this disease. The latter is characterized 

 by localized rotting of the roots and lower nodes of the stalk, and by spots on the blades, 

 sheaths, and husks. The organism has been obtained in 15 isolations from the various types 

 of lesions; and similar lesions have been reproduced by inoculations with pure cultures of the 

 organism, which is as yet unnamed. — B. B. Higgins. 



93S. ScHULTZ, E. S., AND DoNALD FoLSOM. Leafroll, net-necrosis, and spindling-sprout 

 of the Irish potato. Jour. Agric. Res. 21: 47-SO. PI. 1-12. 1921. — The symptoms, geographi- 

 cal distribution, and economic importance of leafroll are briefly discussed. The disease is 

 found to be consistently carried over winter in the tubers. It can be transmitted by means 

 of grafts, using either parts of diseased tubers or scions from diseased plants. The plants 

 show leafroll sjTiiptoms about 1 month after inoculation as well as in their progeny. Obser- 

 vations made in the field and in the greenhouse indicate that aphids are agents of transmission. 

 Experiments with caged plants in the field and in the greenhouse show that aphids are able to 

 transmit leafroll. Two tuber units were inoculated in the field with Myzus persicae, both 

 developing symptoms of leafroll, and showing leafroll in a large percentage of their progeny. 

 Eight plants were inoculated with aphids in the greenhouse and all developed leafroll, while 

 checks grown from the same tubers remained healthy even though some of them were fed upon 

 by non-virulent aphids. An experiment on overwintering in the soil gave negative results. 

 Tubers showing net-necrosis almost invariably produce leafroll plants, although leafroll 

 plants only occasionally produce net-necrosis tubers. Net-necrosis often fails to appear in 

 the progeny of tubers affected with it. The development of net-necrosis by leafroll tubers 

 seems to depend on the variety, time of infection, and other factors not now understood. 

 Net-necrosis is one of the causes of spindling sprout. Experiments with rogueing indicate 

 that this method of control will be effective in northeastern Maine under proper conditions. 

 Leafroll appears to spread less readily than mosaic. — K. H. Fernow. 



939. Stevens, F. L. Foot-rot of wheat. Science 51: 517-518. 1920. — From evidence 

 gathered from a study of the foot-rot disease the author presents the following facts as fully 

 established. The fungus was isolated from lesions in practically every one of several hundred 

 attempts, and no other species of fungus or other parasite was constantly present. The 

 lesions were always penetrated and occupied by a fungus mycelium that agrees in general char- 

 acter with the fungus in question, and the diseased stems, when placed in humid surroundings, 

 became covered with spores of the fungus. The fungus when inoculated from pure cultures 

 as spores, mycelium, or infected wheat tissue produced disease indistinguishable from foot- 

 rot. Wheat planted in soil with an inoculum of this fungus developed typical foot-rot. The 

 fungus in question is a typical Helminthosporium. This foot-rot found in Illinois should 

 be recognized as a disease quite distinct from all others of similar type that have been pre- 

 viously described. It is clearly soil-borne and probably also seed-borne. — A. H. Chivers. 



940. Taubenhaus, J. J. A study of the black and the yellow mold of ear corn. Texas 

 Agric. Exp. Sta. Bull. 270. 38 p., 10 fig. 1920.— The annual loss in Texas from black and yellow 

 molds, Aspergillus niger and A. flavus, is estimated at 5,718,333 bushels. The same molds 

 attack broom corn and stored onions. The black mold is the more destructive to corn. — 

 Tests indicated that while Aspergillus niger is found on peanuts, cotton bolls, cowpeas, onions, 

 pomegranates, Irish potatoes, squashes, broom corn, and ear corn, physiological species do 



