1256 EARLE V. HARDENBURG 



fore, may not be expected to show positive results. On the contrary, 

 positive influence on the yield from spraying with a fungicide for the 

 simultaneous control of late blight (Phytophthora infestans) , early blight 

 (Alternaria solani), and tipburn, as well as for the. control of flea beetles 

 (Epitrix cucumeris), may be expected in most potato regions every year 

 if the spraying is done thoroly. As a standard fungicide, bordeaux mix- 

 ture has been used for this purpose for about thirty-six years, the practice 

 having begun in France in 1885 (Macoun, 1905). Probably the first 

 systematic and continuous series of spraying experiments with bordeaux 

 conducted in this country, were begun by Jones at the Vermont station 

 in 1891. Lutman (1911) has reported a twenty-years summary of these 

 experiments. During this period, late blight occurred fifteen years out of 

 the twenty, the loss in yield from the resulting rot varying from year to 

 year. These tests showed a gain in yield every year from spraying, the 

 percentage of gain per acre ranging from 18 in a year of no blight, to 215 

 in a year of much blight, and the average gain per acre for the twenty 

 years being 64 per cent. Altho the frequency of spraying in these tests 

 varied from one to five times a season, the influence of spraying cannot be 

 studied because different frequencies were not used within any one year. 



Second in importance to the Vermont experiments are those of ten 

 years duration conducted by the New York station at Geneva, under the 

 direction of Stewart, French, and Sirrine (1912). These tests were dupli- 

 cated, one series being conducted on heavy clay loam soil at Geneva, and 

 the other on light sandy loam soil at Riverhead. During the test, late 

 blight occurred six years out of the ten at Geneva and only three years out 

 of the ten at Riverhead. As might be expected, therefore, the greater 

 average gain from spraying was obtained from the Geneva plots. How- 

 ever^ there was not one year out of the ten on either series of plots in which 

 a gain from spraying was not obtained. In years of no blight this gain 

 was attributed to the control of such factors as flea beetles, early blight, 

 bugs, and tipburn. Spraying every two weeks during the growing season 

 was each year compared to spraying but three times. With but one slight 

 exception, the more frequent spraying resulted in the higher yield. The 

 ten-years average difference in yield due to this difference in frequency of 

 spraying was 28.5 bushels per acre for Geneva, and 20.7 bushels per acre 

 for Riverhead. Spraying every two weeks gave a ten-years average gain 

 in yield of 97.5 bushels per acre at Geneva and 45.7 bushels per acre at 

 Riverhead. 



Clinton (1916) reported the results of spraying in a thirteen-years 

 test at the Connecticut station. Altho no data are presented on the 

 influence of the various frequencies of spraying, increased yields ranging 

 from 10 to 101 bushels per acre (the average being 38 bushels per acre) 

 were reported. At this station, also, increased yields due to spraying were 

 obtained every year, including years of no blight, in which the average 



