46 EXPERIMENT STATION EECOED, 



infection, parasitism and immunity, relations between host and parasite in smut 

 diseases, indigenous and introduced species; (2) life histories and treatment of 

 cereal smuts, viz, wheat bunt {Tilletia tritici), loose smut of wheat (Ustilago 

 tritici), flag smut of wheat (TJrocysHs tritici), loose smut of oats {Ustiiago 

 avencB), naked smut of barley (C7. nuda), covered smut of barley (U. hordei), 

 and head smut of maize (Sorosporium reilianmn) ; (3) life histories of various 

 grass smuts, including grain smut of sorghum (Cintractia sorghi-viilgaris), 

 brome grass smut (U. hromivora) , kangaroo grass smuts (three), and Wallaby 

 grass smuts (two) ; (4) field experiments during 1909; and (5) classification 

 and technical descriptions of 11 genera and 60 species. 

 An extensive bibliography is appended, 



Tacts contributing' to the explanation of grain rust epidemics, E. C. John- 

 son (Abs. in Science, n. ser., 32 {1910), No. 816, p. 256). — The author states 

 that wintering uredospores and wind-blown uredospores or secidiospores are 

 usually present in sufficient quantities to start rusts every year. The germina- 

 tion of uredosix»res and the infection in many rusts takes place most easily at 

 the relatively low temperatures of 60 to 70° F. 



Wheat is said to be particularly susceptible to infection at heading time, and 

 if this period is delayed by a late season, or is unduly lengthened by reason of 

 low temperatures, the number of spores falling on each plant is proportionately 

 increased, and the rust is given unusual chances for development. Subnormal 

 temperatures, especially cool nights with heavy dews, are exceedingly favorable 

 to rust infection at this time, being far more so than excessive rainfall due to 

 sudden showers with periods of high temperatures bet\^en. 



An analysis of the climatological conditions over the middle Northwest 

 showed that the most severe epidemics of rust appeared when the temperatures 

 averaged 3.5° subnormal over this region. 



On the outbreak of the leaf-roll disease in Wurttemberg', W. Lang (Wilrt- 

 iemb. Wchnhl. Landw., 1909, Nos. 23, pp. J,20-Jf22; 2Jt, pp. hkh, f)5).— The author 

 discusses the symptoms, causes, and remedies for this disease. 



It is stated that the tubers do not always show indications of the disease, but 

 that the rolling and coloring of the tops is one of the most marked symptoms, 

 although this may be caused by other diseases. 



The disease is said to be prevalent in Wurttemberg, and has materially de- 

 creased the yield. The cause of the disease is not yet known, but regional con- 

 ditions seem to be an important factor in its outbreaks. 



The selection and breeding of highly resistant varieties is recommended as 

 the best means of control. 



New studies on the leaf-roll disease of the potato, R. Schander {Jahresher. 

 Ter. Angeiv. Bot., 7 {1909), pp. 235-2Jf.5). — ^From these studies, the author con- 

 cludes that the leaf-roll disease can be transmitted by means of infected seed 

 tubers, and that the coloring of the fibro-vascular bundles is not a certain indi- 

 cation of the disease. The treatment of the seed potatoes with various fungi- 

 cides produced no effect in controlling the disease, and the use of different kinds 

 of fertilizers was also without effect. The use of sound tubers only as seed is 

 recommended. 



Irish potato blight, D. McAlpine {Dcpt. Agi: Victoria Bui. 21, pp. 5-42, i)ls. 

 16, figs. 5; Dept Agr. So. Aust. Bui. Jf9, pp. 42, pis. 16, figs. 5). — On account of 

 the late blight {Phytophthora infestans) having been discovered in all the 

 states of Australia, the author deems it wise to discuss the life history and 

 damage done by this disease, so that all potato growers will be able to recognize 

 it and take the proper precautions against it. A histoiy of the disease, its oc- 

 currence in New Zealand and Australia, its symptoms, cause, development, 

 favoring conditions, and methods of combating it are given. 



