Jan., 1924] PROGRESS OF AGRICULTURAL EXPERIMENTS 



33 



1 . Effect of Corrosive Sublimate Treatment on Stand. 



The regulation treatment with corrosive subhmate, i.e., submersion of the 

 tubers, even after they have begun to sprout, in a solution containing 4 ounces 

 of corrosive sublimate in 30 gallons of water for 1| hours, was not found to 

 affect the stand. The treatment is entirely harmless whether the potatoes 

 treated are quite flabby or firm. Irregularities in stand sometimes complained 

 of by farmers who have used corrosive sublimate are due to other causes. 



Since corrosive sublimate dissolves more readily when mixed with its own 

 weight of common salt, this practice was also studied and found entirely 

 harmless. 



2. Effect of Spindling Sprout on Yield. 



Spindling sprout tubers were selected from seed placed to green in bright 

 diffuse light. The potatoes selected showed no signs of net-necrosis. The 

 sprouts were removed before the seed was planted. The stand obtained was 

 86.1 per cent perfect, and 93.5 per cent of the plants grown showed symptoms 

 of leaf-roll. The plants yielded on the average 0.42 pounds per hill, the crop 

 being composed mostly of tubers of non-marketable size. 



Thirtj'-one plants produced 13 pounds of tubers, which graded as follows: 



Tubers less than 2 ounces in weight, 67.3 per cent. 

 Tubers 2 to 12 ounces in weight, 32.7 per cent. 



3. Effect of Net-Necrosis on Development of Leaf-Roll and Yield. 



In this experiment tubers were selected from a random sample of Green 

 Mountain seed, in which about 20 per cent of the marketable tubers showed 

 net-necrosis. Four rows of the 36 hills each were planted as follows: 



Row 1. Bud-end of tubers showing net-necrosis only at the stem-end. 



Row 2. Bud-end tubers free from net-necrosis. 



Row 3. Stem-end of tubers, net-necrosis in each seed-piece. 



Row 4. Stem-end of tubers, seed-pieces free from net-necrosis. 



The figures given in the following table show that leaf-roll can be reduced 

 by eliminating tubers affected with net-necrosis, but that if net-necrosis is 

 present in a large percentage of tubers the stock should not be used for seed. 



Table XIII. — Effect of net-necrosis on stand, percentage of leaf-roll and yield. 



Row 1 

 Row 2 

 Row 3 . 

 Row 4 . 



Stand. 



Per cent. 



100.0 

 94.4 

 88.8 



100.0 



Leaf-roll. 



Per cent. 

 97.2 

 55.9 

 78.1 

 50.0 



Yield by 

 hill. 



Pounds. 

 0..59 

 1.03 

 0.81 

 0.82 



Tubers less 

 than 2 ounces 



Per cent. 

 33.72 

 18.43 

 16.35 

 17.80 



Tubers 2 to 12 

 ounces. 



Per cent. 

 66.28 

 81.57 

 83.65 

 82.20 



4. Relative Fertility of Seed Pieces from the Bud-End and Stem-End of the same 



Tuber. 



Certified Green Mountain seed potatoes were cut in half across the middle. 



The bud-ends and stem-ends were then cut into chunky seed pieces, but the 



work was done with no more than the usual care exercised in practice. The 



