148 EXPERIMENT STATION EECOED. 



pliysiological aspects of certain grape diseases, including Plasmopara, Pseudo- 

 peziza traclieipliila, and " Droali." 



Studies of plant diseases, H. C. Muller, E. Molz, and D. Morgenthaleb 

 {Ber. Agr. Chem. Kontroll u. Vers. Stat. Pflanzenkrank. Prov. Sachsen., 1912, 

 pp. 67-76). — This is a condensed report on studies carried out on various 

 diseases of grains, beets, potatoes, fruit trees, and garden vegetables, with a 

 list of remedies and apparatus for their application tested and approved by the 

 station, 



Notes on Cronartium coleosporioides and C. filamentosum, E. P. Meinecke 

 {Phytopathology, S (1913), No. 3, pp. 167, J68).— The author reports the suc- 

 cessful infection of CastiUcia miniata with secidiospores of Peridermium sta- 

 lactiforme from Pinus contorta. 



Mosaic and allied diseases, with especial reference to tobacco and toma- 

 toes, G. H. Chapman {Massachusetts Sta. Rpt. 1912, pt. 2, pp. 41-51). — A report 

 is given of observations on this disease of tobacco and tomatoes which the 

 author says he has been able to produce on other plants, such as ragweed, 

 jjmson weed, etc. 



The disease is held to be of physiological origin and is caused by the exces- 

 sive activity of the oxidase and peroxidase enzyms in the plant and the partial 

 loss of fimction of catalase. It is not considered due to any one enzym alone 

 nor to any special virus. It is infectious but not contagious, and does not 

 occur in seed beds when new soil is used nor in properly sterilized seed beds. 



Directions are given for the handling of the seed beds, the use of fertilizers, 

 the choice of soils, etc., to reduce as much as possible the occurrence of this 

 trouble. A bibliography is appended. 



Cucumber and tomato canker {Oard, Cliron., 3. ser., 5Jf {1913), No. 1393, 

 pp. 167, 168, fig. 1). — This disease, due to Mycosphwrella citrullina, the same 

 fungus which attacks muskmelons in the United States (E. S. R., 21, p. 148), is 

 said to be widely spread in Great Britain, where it is causing considerable loss 

 to tomatoes and cucumbers grown under glass, and it has recently been shown 

 to occur on fruits of tomatoes grown in the open (E. S, R., 29, p. 847). 



The fungus appears to be a wound parasite and is spread most rapidly by 

 the pycnidiospores. On the tomato the symptoms which have been most fre- 

 quently seen are the wilting of the whole or top part of the plant, and the 

 appearance of brown sunken areas on some parts of the stem. These are 

 generally within 1 or 2 in. of the soil, although in some instances the canker 

 may be found farther up the stem. 



Comparatively little is known regarding methods of prevention, but attention 

 to the proper temperature and humidity of the houses and spraying with 

 Bordeaux mixture, it is thought, would tend to prevent the serious occurrence 

 of the trouble. 



White-heads or take-all of wheat and oats {Bd. Agr. and Fisheries [Lon- 

 don]. Leaflet 273, 1913, pp. 4, fig. 1). — ^A brief description of this disease, 

 Ophiobolus graminis, in its different aspects is given with a discussion of its 

 prevalence, mode of attack, and prevention. It is said to flourish also on 

 couch grass, Bromus steiyilis, etc., requiring their suppression or control; like- 

 wise it is said to attack oats, rendering this crop unfit for rotation as a means of 

 starving out the fungus. Blindness or abortion of the grain in the ear may be 

 due to other causes named, but such cases may be recognized by the absence of 

 the characteristic blackening at the base of the stem. 



It is claimed that superphosphate of lime at the rate of 1^ cwt. per acre 

 applied when the crop is young proved effective at Kew, and that in Australia 

 iron sulphate at the rate of 1 cwt. per acre checked this disease. 



