DISEASES OF PLANTS. 789 



to favor its development, and the sclerotia on the seed tubers are believed to be the 

 principal means of disseminating the disease. When the field is once infested with 

 tbe fungus other crops should be grown for at least 3 years, and care should be exer- 

 cised in the preparation of the soil and the use of irrigation water. 



Late planting frequently gives better results than early planting. The practice of 

 scattering the old stems over the potato fields should beabandoned; all old potato 

 steins should be gathered and burned after harvest. Care should lie exercised in 

 storing potatoes to keep them at a uniformly low temperature, and if spread in the 

 li'_dit and air for several weeks before planting they will produce strong, hardy 

 sprouts which are better able to resist the attacks of the fungus. 



Notes are given on the possibility of developing disease-resistant varieties, seed 

 selection, and treatment where potatoes are planted in uninfested soils. Treating 

 with corrosive sublimate or formalin may be recommended, the corrosive; sublimate 

 being preferred. Where the seed tubers are soaked in these solutions and planted 

 in infested soils decided losses have been observed. The use of sulphur and lime 

 have been without any benefit. A detailed account of the experiments, together 

 with their results, completes the bulletin. 



Large potato vines and no potatoes, W. Paddock ( ( 'olorado Sta. Bui. 92 pp. 8, 

 ph. .'). — This bulletin contains a condensed and popularized statement of the work 

 on potato diseases at the Colorado Station, most of which has appeared in Bulletins 

 70 and 91 of the station (E. S. R., 14, p. 159; 16, p. ). 



Some diseases of cane considered in relation to the leaf-hopper pest and 

 to the stripping of cane, R. C. L. Perkins {Hawaiian Sugar Planters' Sta. Rpt. 

 1904, PP- 63-66). — A discussion is given of some of the diseases of sugarcane, particu- 

 lar attention being paid to the relationship between the stripping of cane and the 

 leaf-hopper pest and the distribution of the diseases. The principal diseases are the 

 different forms of Trichosphseria sacchari, of which the pineapple disease, root dis- 

 ease, and "cane spume" are described. 



In order to prevent the occurrence and spread of these diseases, the author sug- 

 gests that unless it is absolutely necessary for reasons of cultivation, no cane should 

 lie stripped so as to expose the joints while the rind is still soft. When stripping 

 is followed the leaf hoppers are able to deposit their eggs more readily, and through 

 these injuries the fungus may obtain entrance to the plants. 



Observations on the Botrytis rot and drop of lettuce, II. .1. Ramsey | Wiscon- 

 sin Sta. I<j>L 1904, pp- 279-28S, Jig*. 2). — An account is given of experiments with 

 head lettuce in the station greenhouses during the past winter. The experiments 

 for the most part were unsuccessful owing to attacks of disease. The house was new 

 and the soil fresh, and no trouble was anticipated, but after a period of vigorous 

 growth the tips of the leaves were found to be burned although no trace of any 

 organisms could be found. A few days after the appearance of the burning of the 

 plants the color turned to a buff brown and the characteristic mycelium of Botrytis 

 cinerea could be observed. The inner and more tender leaves of the head were the 

 first to be attacked, after which the progress of the fungus was very rapid. Soon 

 after the watery decay of the leaves began the characteristic gray mold appeared on 

 the surface. This same fungus was found on decaying organic matter where it was 

 living saprophvtically, but in the above cases it was truly parasitic. Numerous 

 experiments were made to inoculate healthy plants from the spores, but only when 

 the plants were placed under bell jars and kept very moist were any infections 

 secured. 



A disease termed black rot was observed in a few cases, the infection usually tak- 

 ing place where the leaves were in contact with the soil, and the mycelium growing 

 through the midrib and veins to the stem. Later the leaves fell from the stem, 

 leaving dark spots where they had been attached, and on account of this character 

 the disease has been termed the black rot. 



