ANNUAL REPORT, 1947-48 13 



Tests of Spray Materials for the Control of Late Blight of Potatoes. (C. V. 



Kightlinger and H. M. Yegian.) It is the object of this investigation to compare 

 the effectiveness of some of the newer fungicides with the standard Bordeaux 

 mixture for controlling late blight of potatoes, and to determine the effect of 

 these materials on vine growth and production. 



In 1947 the investigation was confined to the use of Bordeaux mixture, neutral 

 copper (COCS), Dithane 14, and Dithane 278. Test plots of one-thirtieth acre 

 were established for each kind of fungicide and for one check treatment where no 

 fungicide was used. The plots were all replicated four times and were randomized. 

 Green Mountain potatoes were used as the test crop and were sprayed with 

 recommended rates of fungicide at weekly intervals from mid-June until frost 

 killed the vines in late September. Insects were controlled as needed with sprays 

 containing DDT and nicotine. 



Late blight occurred too lightly in 1947 to make the results conclusive; how- 

 ever, the more evident observations can be summarized as follows: 



1. Bordeaux mixture was the most effective of the fungicides tested for con- 

 trolling late blight, but it caused a noticeable depression in the growth of the 

 plants. 



2. Neutral copper, Dithane 14, and Dithane 278 were about equally effective 

 in controlling late blight, but were less efficient than the Bordeaux mixture. 

 These materials did not depress the growth of the vines significantly. 



3. With all of these fungicides, spraying at weekly intervals was not sufficient 

 to completely control the blight during the time the plants were growing the 

 fastest. 



Potato Variety Trials. (Karol J. Kucinski and Ralph W. Donaldson.) Eight 

 potato varieties commonly grown in this region have been tested annually with 

 respect to their j'ielding qualities. Based on 10 to 14 year averages, the varieties 

 rank themselves in the following order: Green Mountain, 436 bushels; Chippewa, 

 368; Russet Rural, 364; Houma, 342; Warba, 336; Irish Cobbler, 308; and 

 Sebago, 305 bushels. 



Soil Conservation Research Projects. In cooperation with the Research 

 Division of the Soil Conservation Service, United States Department of Agri- 

 culture. (Karol J. Kucinski, Project Supervisor.) 



A Survey of Erosion Problems Arising from Changes in Soil Use. The com- 

 mercial growing of potatoes in the western foothills and plateaus of Massachu- 

 setts has become well established during the past few years. Old sod and pasture 

 lands which have not been plowed for as many as thirty years are now being 

 cleared and put into potato production. Since the potato fields are rather large 

 areas located on sloping hillsides, where the season does not permit the use of 

 winter cover crops, considerable soil erosion has taken place. Periodic analysis 

 of the soil taken from selected areas shows that in nearly all cases the organic 

 matter content has decreased more than 50 percent from what it was five or six 

 years ago. The farmers realize that their soils are deteriorating rapidly, and are 

 calling on the Soil Conservation Service "Operations" for technical aid in solving 

 their problems of erosion and soil depletion. Contour planting, terracing, and 

 rotation with green manure crops are the control measures recommended. 



Studies io Determine the Effects of Loss of Top Soil on Crop Yields. In order 

 to illustrate the value of top soil and organic matter, a field experiment was 

 initiated, in which the top soil (to plow depth) was totally removed from a plot 



