ANNUAL REPORT, 1938 61 



With S-S-50 Bordeaux With 5-3-50 Bordeaux 



Material 



Yield Percentage 



per Acre of Crop 



Bushels Grade 1 



Check (Bordeaux only) 478.3 78.4 



Derris (4 percent rotenone) 480 78.5 



Cube (4 percent rotenone) 471 . 6 75 . 1 



Commercial 2 percent rotenone. . . 457.5 83.1 



Calcium arsenate (Calrite) 45 1 . 6 72.3 



Calcium arsenate-arsenite 43 1 . 6 72.6 



Calcium arsenate (Calgreen) 416.6 75.2 



All of the materials gave slightly higher yields with the 5-5-50 Bordeaux. The 

 commercial calcium arsenate-arsenite mixture when used with 5-3-50 Bordeaux 

 caused severe burning of the foliage, which was reflected in the low yield. 



Two commercial brands of copper sprays designed for use on potatoes were 

 compared with 5-5-50 Bordeaux mixture. Tests were also made of the value of 

 excess lime with each of these materials. Ten applications were made during 

 the season. The relative value of the materials, based on yields, was as follows: 



Yield per Acre Percentage of Crop 

 Material . Bushels Grade 1 



Bordeaux 5-5-50 



Basic copper sulfate 4-Hme 



Basic copper sulfate 



Copper hydro +lime 



Copper hydro 



The addition of lime to the commercial materials in each case improved the 

 coverage and adhesiveness of the sprays. None of these spra\s, however, equaled 

 homemade Bordeaux in these qualities, and the superiority of the Bordeaux- 

 sprayed plots was apparent throughout the season. The correlation of increased 

 yields and superiority in coverage and persistence indicates that these were very 

 important factors in a year such as 1938 when the rainfafl during the spraying 

 season was more than double the normal. 



In the period of unsettled weather which culminated in the hurricane, there 

 was a total rainfall of approximately 12 inches which not only completely sat- 

 urated the soil but actually flooded parts of the experimental plots. The soil 

 dried very slowly, and in low areas still retained much moisture at the time the 

 potatoes were dug. The saturation of the soil prevented proper aeration and 

 exerted a smothering action on the tubers which led to internal breakdown. This 

 condition, which was noted in practically all of the plots regardless of treatment 

 and in fact was generally distributed throughout the entire Valley, materially re- 

 duced the net yield. The damage was much more severe in those low areas which 

 were submerged by the high water, and was another by-product of the hurricane. 



Control of Onion Thrips. (A. I. Bourne.) Weather conditions during late 

 spring and early summer were as a whole favorable for the onion crop. Moderate 

 temperatures and ample rainfall promoted rapid growth while thrips were some- 

 what late in appearing and developed slowly. The prolonged warm period from 

 June 18 to 24, with little or no precipitation, threatened the appearance of blast, 

 but the intervention of nearly 5 inches of rain on June 26 and 27 accompanied bj' 

 comparatively low temperature halted the blast and at the same time retarded 



