844 EXPERIMENT STATION RECORD. [Vol.43 



a spray containing 0.6 per cent copper sulphate did not injure the fruit or foliage 

 of the apple. 



The results of this investigation are presented as a basis for further studies 

 to be conducted in various parts of the country. 



How the protection of plants has progressed in Quebec, G. Mahettx 

 (Ann. Rpt. Quebec Soc. Protect. Plants [etc.], 11 (1918-19), pp. 56-58).— The 

 author deals concretely vv'ith the use of fungicides and insecticides with a few 

 crops, notably wheat and potatoes, both of which showed, striking net gains due 

 to protective treatments. 



Flag smut and take-all, G. M. Reed and G. H. Dungan {IUin<yis Sta. Circ. 

 242 {1920). pp. 1{, fig. 1). — Results are given of an extensive survey of the wheat 

 fields in the vicinity of Granite City, 111., where flag smut made its appearance 

 in 1919. Flag smut is reported as having been found in 111 fields, comprising 

 2,500 acres, but so far has not been found outside this area. The authors give 

 a brief discussion of the appearance and methods of control of the disease, the 

 most promising control measures being the treatment of seed grain, burning of 

 straw, and planting of resistant varieties. 



The same measures are recommended for the control of take-all, and precau- 

 tionary measures are also being taken to prevent the further spread of this 

 disease. 



A comparative morphological study of aecia of four different rusts found 

 upon barberries in North America, H. R. Rosen and R. S. Kirby {Phyto- 

 pathology, 9 {1919), No. 12, pp. 569-574, Pls. 2, fig. 1). — Results are given of 

 morphological studies of Puccinia fendleri, P. oxalidis, P. graminis, and Mcidium 

 butlerianum, heteroecious rusts which produce secia on barberries. The last 

 species is described as new. 



Presoak method of seed treatment: A means of preventing seed injury 

 due to chemical disinfectants and of increasing germicidal efficiency, 

 H. Braun {Jour. Agr. Research [TJ. S.], 19 {1920), No. 8, pp. 363-392, pis. 14, 

 figs. 9). — According to the author, the use of formalin and copper sulphate as 

 now practiced usually causes retardation and injury to seed germination. 

 Greenhouse and field experiments, carried on by the Bureau of Plant Industry, 

 U. S. Department of Agriculture, have shown that this detrimental effect can 

 be eliminated for standard varieties of wheat by allowing the seeds to absorb 

 water for six hours before submitting them to treatment with formalin or 

 copper sulphate. Soaking for a short period (10 minutes) and covering for 6 

 hours is said to be better than leaving the seed in water for 6 hours. Similar 

 results were obtained in experiments with barley, oats, and oorn. 



The saturation of the seed cells and cell walls with water during the presoak 

 period is thought to be the factor counteracting the injurious effect upon seed 

 germination by diluting the disinfectant beyond the point of injury. Actual 

 stimulation of germination is said to have been observed in presoak-treated .seeds, 

 a factor which by shortening germination minimizes the danger of exposure to 

 the attack of soil organisms during the susceptible period. 



The use of the presoak method is said to increase the efficiency of the disin- 

 fectant, in that the presoaking stimulates dormant bacteria and pos.sibly fungi 

 into vegetative activity, thereby rendering them extremely susceptible to the 

 subsequent action of the disinfectant. 



In applying the principles stated by the author to other seeds, the determina- 

 tion of the length of time for the presoak period and the subsequent disinfectant 

 treatment is governed by the rate of absorption of water by the seed, the sus- 

 ceptibility of the seeds and pathogens to the disinfectant, and the periods neces- 

 sary for the beginning of seed germination and of vegetative activity on the 

 part of the pathogen. 



