DISEASES OP PLANTS. 53. 



South Wales of the American corn smut (Ustilago maydis) on Funk Yellow 

 Dent, an American variety of corn. The smut was fotmd on a few plants at 

 the Bathurst Experiment Farm, and occurred on the stems, leaves, tassels, 

 and ears. 



Studies In plant diseases, B. F. Lutman (Vermont 8ta. Bui. 159, pp. 216- 

 225). — Brief accounts are given of some of the common diseases observed in 

 Vermont, together with a description of experiments conducted in spraying pota- 

 toes to determine the effect of the treatment upon the plants. 



Earlier investigations indicated that Bordeaux mixture has a stimulating 

 effect upon the plant in addition to a protective one, and in previous trials (E. 

 S. R., 24. p. 447) an attempt was made to determine what constituent of Bor- 

 deaux mixture produced the stimulus. In the present paper the results are 

 given of experiments carried on with Bordeaux mixture and Bordeaux mixture 

 to which iron sulphate was added. Different plats were sprayed with these 

 fungicides, and in one lot only the lower part of the plants received the fungi- 

 cide. The potatoes were harvested at different times, and before maturity the 

 weight of the plants was determined. 



From the results obtained it was found that the plants to which Bordeaux 

 mixture had been applied stored more starch than those not so treated. Where 

 iron sulphate was added to the Bordeaux mixture it seemed to have practically 

 the same stimulating effect as the ordinary Bordeaux. As there was little or 

 no disease present the fungicidal value of this mixture was not determined. 



Potato diseases and the weather, B. F. Lutman {Vermont Sta. Bui. 159, pp. 

 248-296, dgms. 20). — ^The author gives a discussion of the relation of potato 

 diseases to weather conditions, based on the data obtained by the station during 

 the period covered by the 20 years' experiments on spraying for the control of 

 potato diseases (see below). 



During this period two severe blight infestations are noted and two periods 

 when there is little or no disease. Rainfall is said to have much to do with the 

 spread of the disease, and in general a rainy season is likely to be accompanied 

 by an epidemic of blight and rot. However, in 1901 the rainfall was small, and 

 it was one of the worst seasons on record, both as to the damage done to the 

 foliage and to the tubers. 



In connection with the reappearance of disease there is always to be borne in 

 mind the manner in which the fungus causing it is perpetuated from year to 

 year, and this brings up the hypothesis of the existence of some type of resting 

 spore, as claimed by Jones (E. S. R., 22, p. 346). 



Twenty years' spraying for potato diseases, B. F. Lutman {Vermont Sta. 

 Bui. 159, pp. 225-247). — A summary account is given of the experiments which 

 have been carried on for 20 years by the station on the control of potato diseases 

 by spraying. The methods of applying fungicides and the results are given 

 for the different seasons, and summarizing the work for the entire period 

 the author states that by the application of Bordeaux mixture there was an 

 average increase for the 20 years of 105 bu. per acre, or 64 per cent gain. The 

 extreme range was 18 per cent gain in 1910. when there was no disease, as 

 compared with 215 per cent in 1901. when diseases were very prevalent. 



[On the primary infection of potatoes by late blight], G. H. Pethybkidge 

 {Scd. Proc. Roy. Dublin Soc, n. ser., 13 {1911), No. 2, pp. i2-27).— This is prin- 

 cipally a controversial article on the infection of the potato crop with late 

 blight (Phytophthora infestans) by means of mycelium derived directly from the 

 planted tubers. 



After a general discussion of the theories of A'arious investigators on this 

 subject and a statement of the results obtained from his own experiments, the 



