DISEA8E8 OF PLANT8. 1077 



The occurrence of plant diseases in Vermont in 1904, L. It. JONBS and W. J. 

 M0K8E (Vermont Sta. Rpt, 1905, pp. 967-271).- Data are given showing the mean 

 temperature, rainfall, number of clear and cloudy days, etc., and the authors call 

 attention to the close relationship between plant diseases and weather conditions. 



Brief notes are given on a number of diseases observed during the period covered 

 by the report, particular attention being given to those of the potato, and 2 new leaf 

 spot diseases arc described. The lir-t of these diseases made it- appearance early in 

 July, a few plants showing small black .-pots on the leaves, which suggested the 

 presence of early blight. Upon closer observation it was seen thai the blackening 

 began on the under side of the veinlets and spread more rapidly along the veins than 

 laterally. No fungus was detected in connection with the spotting. One bill of 

 affected potatoes was dug and the root system, tubers, and bases of the stem seemed 

 sound. The other infected plants were kept under observation until the death of 

 the plants in September. The spots gradually enlarged, still bearing a close resem- 

 blance to the early blight, hut remained sterile. 



In the authors' judgment it is a nonparasitic disease, involving the planl as a whole, 

 the local spotting of the disease being mei-el\ a symptom. It i> believed to be the 



same disease observed by one of the authors in < .eri nan y and also in England, ami a 

 similar trouble was noticed on specimens of the .Mexican Solarium polyadenium in the 

 horticulturist's potato collection. 



The other disease appears to be unrecorded in this country and was first notice! 

 on early planted Early Rose potatoes. The plants exhibited obscurely defined pale 

 yellow spots I to \ in. in diameter, and the lower surfaces of the spots were covered 

 with a delicate gray growth, evidently a ( Jercospora. In the gross appearance of the 

 spots and in its occurrence and destructiveness the disease was much like that caused 

 by Cladosporium fulvum, which was developing at the same time on neighboring 

 tomato plants. This disease spread during July to another variety of potatoes in an 

 adjacent plat and showed slight development in other plats later in the season. It 

 caused considerable damage from hastening the death of the vines of the earlier 

 potatoes, but did no appreciable harm on the later varieties. 



The fungus is being studied to determine its specific and cultural characters. 



The part taken by teleutospores and eecidia in the distribution of maize 

 and cereal rusts, J. C. Arthur ( Proc. Soc. Prom. J;//'. Sci., vq (/.van, pp. 94-98). — 

 Attention is called by the author to the recent discovery of the a-cidial stage of corn 

 rust on the common wood sorrel ( ( tealis sp. ). 



Hitherto this form of the rust had not been known and know ledge of the life his- 

 tory of the fungus remained incomplete. Having discovered the secidial stage of the 

 rust, this gap is filled, but the author states that the usual infection is probably through 

 the blowing of the uredospores from the regions where the corn is not completely 

 killed by frost. The blowing northward of these spores may cause successive infec- 

 tions in new localities as the season advances, and thus spread the rust throughout 

 the country. In addition the germinating teleutospores reach plants of Oxalis, from 

 which direct infection to the corn plant becomes possible. 



The distribution described above for the corn rust is said to apply almost equally 

 well to some of the rusts of other cereals. 



Rust problems, H. L. Bolley and F. J. Pritchard ( North Dakota Sta. Bui. 68, ppl 

 607-676, figs. SO). — An account is given of rusts of cereals and other plants, the prin- 

 cipal aim of the bulletin being to provide a compendium of the theories and known 

 facts involved in the rusting of cereals and other important farm crops, to give the 

 lines and results of new observations and experiments, and to cite investigations and 

 farm practices which give promise of future success in combating or preventing crop 

 destruction by these fungus pests. The authors describe various forms of rusts, giv- 

 ing an account of their effect on the host plants, the alternate generations of a num- 

 ber are mentioned, and accounts given of the method by which the fungus is carried 

 over from one season to another. 



