DISEASES OF PLANTS. 245 



the seed and the soil aliout it for a space of an inch or so was moistened with 

 dilute formalin the onion smut would be prevented to a considerable extent. 



The disease of radishes described is apparently a new one and is attributed 

 to Ascochi/ta sp. It was observed in a number of instances and in some cases 

 caused considerable injury to tlie seedlings. Experiments were carried on to 

 determine the effect of sterilization of tlie soil, and this proved an efficient 

 remedy. 



The celery crown rot, which is said to have been quite destructive in some 

 localities, is of a bacterial nature, but the symptoms of the disease do not 

 coincide with those of any previously described. A study is being made of the 

 trouble, both in the laboratory and in the Held. 



The presence of nematodes in greenliouse-grown lettuce is rei)orted, this being 

 the only instance where this crop was observed to be affected in this manner 

 for about 10 years, although the greenhouse then infested has been used for 

 growing lettuce and cucumbers during this time. In investigations which have 

 been carried on for some time, the autlior found that subirrigation was quite 

 efficient in controlling the nematodes in the case of cucumbers, no galls being 

 noticed on the roots where the plants were subirrigated. while those that were 

 top-watered were in all cases severely infected. It is thought that probably 

 the ai)i)lication of excessive amounts of water for brief periods may prove 

 a practical method of ridding the soil of this pest. On account of the popular 

 belief that lime exerts an influence on nematodes, the author has investigated 

 the subject and finds that lime has little or no effect upon tliem. Summarizing 

 the various methods which have been suggested for destroying nematodes, the 

 author recommends sterilization of the soil, hard fi-eezing. thorough drying, the 

 use of abundant water, as described above, and trapping, or the catch-crop 

 method, which has been found successful in Germany. 



Report of the botanist, G. E. Stonic iMass<i(ini.'<(tts K/r/. Rpt. 190S, pt. 2, 

 pp. 52-54). — A synopsis is given of investigations carried on under the author's 

 directions during the period covered by the report, including studies of a large 

 number of plant diseases. The season is said to have been unusually dry and 

 on this account many of the more common fungus diseases were not as abundant 

 as usual. 



Report of the plant patholog-ist, G. L. Fawcett (Porto Rico Sta. Rpt. 1908, 

 pp. 35, 36). — A report is given on a preliminary survey of the diseases of citrus 

 fruits, pineapples, and sugar cane prior to beginning laboratory and field experi- 

 ments as to their causes and means of prevention. 



Relation between the weather and the occurrence of plant diseases, K. 

 Stormer (Landw. Wchnschr. Sachsen, 11 (1909), Nos. 20, pp. 202, 203; 21, pp. 

 210-212). — A discussion is given of the relation of temperature, rainfall, soil 

 moisture, etc., to the prevalence of disease in various crops. 



The disposition and immunity of agricultural crops toward parasitic fungi, 

 E. Henning (K. Landthr. Akad. Hciiidl. och Tidskr., .',8 (1909), .Vo. 3, pp. 

 112-211). — A general resume of our pi'esent knowledge of the subject. 



The author concludes that barberry shrubs should be dug up and destroyed, 

 this being especially important in the case of shrubs in the vicinity of grain 

 fields. Borders of wild grasses between and around grain fields should be cut 

 often, so as not to form centers of contagion by spreading uredospores to the 

 small grains. 



The hot-water treatment for seed g'rain at creameries, F. K. Ravn and O. 

 Elberg (Landmandsbhide, J,2 (1909), Nos. 1',, pp. 181-186; 15, pp. 193-196).— 

 The paper describes an arrangement made at Danish creameries for treating 

 seed grain according to the hot-water method, the work being done by the 

 regular creamery help. 



