56 BOOT-KNOT AND ITS CONTROL. 



harmless. Abbey also recommends 3 ounces of Little's soluble phenyl 

 in 3 gallons of water applied around affected roots. Dyke^ and 

 Iggulden ^ also tried the latter, but Dyke found it a failure, claiming, 

 however, that kainit was effective. 



FERTILIZERS. 



Closely related to the use of chemicals may be considered the effect 

 of various fertilizers on the development of root-knot. At Monetta, 

 S. C, the following fertihzers were tested in 1906, mostly in one- 

 twentieth acre plats separated by ditches (or rather very deep furrows) 

 2 feet ^vide, the numbers in parentheses referring to the field numbers 

 of the plats: (12) Kainit, 1,000 pounds per acre; (13) ammonium sul- 

 phate, 667 pounds per acre; (14) kainit, 500 pounds per acre; (15) 

 high-grade potassium sulphate, 1,000 pounds per acre; (16) check; (17) 

 high-grade potassium sulphate, 500 pounds per acre; (18) 17 per cent 

 acid phosphate, 1,000 pounds per acre; (19) 17 per cent acid phosphate, 

 1 ton per acre; (20) check. In 1907 the following tests were made: 

 (1) Kainit, 1,000 pounds per acre; (2) kainit, 1,500 pounds per acre; 

 (3) high-grade potassium sulphate, 667 pounds per acre; (4) high-grade 

 potassium sulphate, 1,333 pounds per acre; (5) ammonium sulphate, 

 1,000 pounds per acre; (6) muriate of potash, 1,000 pounds per acre; 

 (7) potassium magnesium carbonate, 667 pounds per acre; (8) potas- 

 sium magnesium carbonate, 1,333 pounds per acre. The checks 

 received no numbers in 1907. The plats of that year and the checks 

 were planted to tomatoes, okra, beans, and New Era cowpeas, all of 

 which are very susceptible to root-knot. The last year's plats (1906 

 experiments) were also replanted in 1907 \vdth these four plants. In 

 1906 the fertihzer plats were planted with New Era cowpeas and 

 summer squashes. To all of the fields was applied each 3'ear, at the 

 rate of 500 pounds per acre, a special brand of commercial fertilizer 

 in common use in that vicinity, the soil being so poor that without 

 some complete fertilizer nothing would grow well. The experiments 

 were intended to show the effect, if any, of an excess of some par- 

 ticular fertilizer over the normal quantity applied. 



The 1906 plats showed plainly the beneficial effects of potash fer- 

 tilizers on the sandy soil of the experimental field. All the plats 

 treated with kainit and potassium sulphate were darker green and the 

 plants were far more vigorous than on the other plats. In fact, plats 

 12 and 15, respectively, kainit and potassium sulphate, both 1,000 

 pounds to the acre, were, so far as the cowpeas were concerned, hard 

 to excel anywhere. The squashes did not show much difference in 

 any of the plats. They were badly infested with the squash bug, 



1 Dyke, 1897. » Iggulden, 1898. 



217 



