DISEASES OF PLANTS. 345 



under such conditions were examined for the presence of catalase. Both the 

 a and ;8 forms of catalase were present in the tomato leaves, although there 

 appeared to be a decided deficiency of insoluble catalase in the leaves of the 

 tomato when affected with the mosaic disease. 



A study was made to determine the effect of light, heat, and moisture as 

 factors in the susceptibility and immunity to disease. 



The occurrence of plant diseases in 1907, N. J. Giddings {Vermont Sta: Rpt. 

 1907. pp. 328-334). — Notes are given on a number of plant diseases which were 

 under observation during 1907. These include several diseases of potatoes, some 

 orchard diseases, and diseases of garden crops. 



Among the diseases of garden crops not hitherto reported was a muskmelon 

 rot which developed toward the close of the season and caused considerable loss. 

 The rot usually appeared on the lower side of the fruit, and when attacked the 

 interior flesh was completely decayed around the point of infection and pos- 

 sessed a disagreeable odor. An examination showed that the disease was due 

 to bacteria. The organisms were isolated and transfers and inoculations made, 

 the inoculations resulting almost always in complete decay of the fruit within 

 from 3 to 5 days. In addition to muskmelons, the organism, which is a wound 

 parasite, seems to be able to infest cucumbers, but the action is much slower, 

 only about one-third of those inoculated giving evidence of the disease. 



Report of the vegetable pathologist, D. McAxpine {Rpt. Dept. Agr. [Vic- 

 toria], 1905-1907, pp. 26-37, flgs. 12). — This is a brief account of the various 

 investigations carried on by the author during the period covered by the I'eport, 

 and includes notes on flax rust, alfalfa rust, flag smut of wheat, potato scab, 

 brown spot of potatoes, etc. 



In the investigations with flax rust a decided difference in susceptibility to 

 disease was noted, Russian and Japanese flax apparently being quite free 

 from the fungus, while plants grown from Calcutta seed w^ere almost entirely 

 destroyed. 



The flag smut of wheat (probably due to Uroci/stis occulta) is said to be a 

 serious disease, and in certain districts of Victoria considerably reduces the 

 yield in seasons favorable for its development. Pot experiments were conducted 

 to determine the manner in which this smut is carried over from year to year, 

 and it was shown that the smut developed only when the seed was dusted with 

 spores, indicating that it is through the young seedlings that the attack is made 

 and that there is no infection through the above-ground parts of the plant. 



An account is given of successful experiments in the prevention of potato scab 

 through the treatment of the seed with corrosive sublimate. Notes are also 

 given on a disease of potatoes called brown ring, which is particularly liable to 

 occur in the variety Beauty of Hebron, and on brown spot. The cause of neither 

 of these diseases is definitely known. 



Rusts of cereals and other plants, E. W. Olive {South Dakota Sta. Bui. 109, 

 pp. 3-20, figs. 5). — The life histories of a number of the more common species 

 of rusts are described and attention is called to the losses due to the presence 

 of these fungi, particularly upon cereals. Suggestions based on life history stud- 

 ies are given concerning means by which the losses may be greatly reduced. 



Cotton wilt in the Central Provinces, G. Evans {Agr. Jour. India, 3 {1908), 

 Xo. 1. pp. 78-80). — The presence of cotton wilt, due to Ncocosmospora vasin- 

 fccta, on the experimental farm at Nagpur is noted. A local variety, Bani, of 

 rather fine staple was first attacked, the signs of the disease appearing toward 

 the end of August, and the attacked plants often being completely destroyed 

 within 24 hours. 



An examination of the diseased material showed that it was due to the above- 

 named fungus. A number of other Indian varieties were attacked to a greater 



