li;:20] DISEASES OF PLANTS. 447 



to head, Including those known as rosette, tip burn, black heart, etc., have been 

 foiiiKl to be associated with a root rot apjiareiitly due to Fusarium sp. Soil 

 sterilization by use of steam or formaldehyde gave only partial control, and this 

 is thought to be due probably to incomplete sterilization of the lower layers of 

 the soil, — 



Potato spraying trial [Long Ashton] {Gard. Chron., S. scr., 66 (1919), 

 No. HIT), p. 2-3.i). — The report for 191S of the Agricultural and Horticultural 

 Research Station, Long Ashton, England, gives information regarding the 

 results of spraying potatoes with copper fungicides. No protection is afforded 

 by spraying unless the materials adhere to the leaf surface. 



Fiisariuni wilt of potato iu the Hudson Kiver Valley, New York, 

 1{. J. llASKKi.r. il'hi/toputhology, 9 (1919), No. 6, pp. 223-260, pis. 3).— Field 

 and laboratory studies are reported on a disease of tlie potato that assumed 

 .serious proportions in the Hudson lliver Valley, New York, in 1914. The 

 .symptoms of the di.sease are practically the same as described by other writers 

 for Fusarium wilt except that tlie tubers commonly exhibited a condition in which 

 the vascular system near the stem end was browned without the causal organism 

 being present. Experiments showed that Fusarium oxyspotum was the primary 

 cause of the disease, and an eflrort was made to discover the possible reasons 

 for a necrosis of the tuber in the absence of any organism. It is thought that 

 the apparently nonparasitic affection of the tuber accompanying Fusarium 

 wilt may be explained on the basis of the presence of toxins. 



Studies were made of the temperature relations of tlie fungus, and a distinct 

 correlation was found between the amount of disease and factors influencing 

 the soil temperature, such as altitude, exposure of fields, and shading of the 

 plants. Tlie most practical solution of the problem is believed to be the planting 

 of early potatoes very early in the season, so that the crop will be matured 

 before temperature conditions become favorable for the Fusarium wilt. 



Experiments with lime, acid phosphate, and soil fungicides on land 

 infested with root rot disease of tobacco, G. C. Routt {Abs. in Science, 

 n. ser., 52 {1920), No. 1332, p. H). — Experiments are reported in which an 

 attempt was made to control root rot disease by applications of lime, acid 

 phosphate, mixtures of lime and .sulphur, dilute sulphuric acid, land plaster, 

 copper sulphate, potassium polysulphid, gas lime, ferrous sulphate, and for- 

 maldehyde, but the results obtained led to tiie conclusion that the disease could 

 not be controlled in this way. 



A disease of tomato and other plants caused by a new species of 

 Phytophthora, G. H. Pethybridoe and H. A. Laffeety (Sci. Proc. Roy. Dublin 

 Sac, n. ser., 15 (1919), No. S5, pp. ^87-505, pis. S).—A disease attacked in 1916 

 nearly 50 per cent of young tomatoes in a Dublin nursery and appeared re- 

 cently at other points in Ireland, perhaps also in England. The attacking 

 fungus is considered as a new species, which is described under the name 

 Phytophthora cryptogca. A closely similar disease noted in Petunia yielded a 

 fungus which after being grown in pure cultures proved to be pathogenic to 

 this and other plants. Tlie disease harbors in the soil, working upward in 

 the plant to the ground level and causing a basal rot. Methods of control are 

 outlined. 



A comparison of the late blights of tomato and potato, N. J. Giddings 

 and A. Berg (Phytopathology, 9 (1919), No. 5, pp. 209, 210, pi. l.—A prelimi- 

 nary reiwrt is given of investigations which are believed to indicate that the 

 Phytophthora on the tomato is somewhat different biologically from that usually 

 found on the potato. The authors have been studying this problem for some 

 time, and during 1918-19 several series of inoculations were made on tomatoes 

 and potatoes with three strains of Phytophthora infestans, one of which was 



