CONTROL OF ROOT-KNOT. 55 



ammonia, which that author supposed might have value in destroy- 

 ing the pest. The writer's experiments at Monetta, S. C, were as 

 follows: Plats of nematode-infested land 10 feet by 70 feet and 10 by 

 140 feet were laid off, separated from one another by ditches 2 feet 

 wide. The chemicals were scattered on the surface and worked in 

 with a cultivator or hoe. The rate per acre of the applications is 

 here given, not the actual quantity put on the particular plats. 

 (1) Water-slaked lime (quicklime put in a hole in the damp earth and 

 left several days until slaked to a powder) 2 tons per acre, ammonium 

 sulphate 1 ton per acre; (2) quicklime 2 tons, ammonium sulphate 

 1 ton; (3) slaked lime 2 tons; (4) quicklime 2 tons; (5) check. Sum- 

 mer squashes were planted on one half of each plat and New Era 

 cowpeas on the other half, both these crops being very susceptible to 

 nematodes. 



Plats 3 and 4, respectively, slaked lime and quicklime, showed a 

 very great abundance of root-knot, even more than plat 5, the check. 

 The plants were pale in color and weak. Evidently lime in the 

 quantities used is not effective against root-knot. In plats 1 and 2, 

 ammonium sulphate plus slaked lime and quicklime, respectively, the 

 squash roots were fairly badly knotted, especially in plat 1, but not 

 nearly so badly as in plats 3 and 4 or in the check plat (5). The cow- 

 peas were very dark green in color and very vigorous, and only moder- 

 ately affected with root-knot, far less than plats 3 or 4, perhaps 

 about like the check. The two plats with ammonium sulphate 

 ripened their seed earlier than any other of the experimental plats. 

 The next year these plats were again planted, this time to cowpeas, 

 okra, tomatoes, and beans. The chemicals were not added, but 

 observations were made to determine whether any beneficial effect 

 might show the second year. The ammonium-sulphate plats were 

 distinctly better than the check or those with lime alone, and were 

 only moderately affected with root-knot, although by no means free 

 from it. 



Experiments similar to these but on a very much smaller scale were 

 made in Miami, Fla. Quicklime, even at the rate of 5 tons to the acre, 

 did not suffice to prevent nematode injury, while root-knot was quite 

 abundant in a plat treated Avith quicklime at the rate of 2 tons per acre 

 with 2 tons per acre of ammonium sulphate dissolved and poured over 

 the surface. 



We must then conclude that these chemicals are not of special value 

 for the combating of nematodes. 



Abbey * recommends using silicofluorid of ammonium at the rate 

 of 1 ounce to a square yard. It must not be applied to soil containing 

 living plants, as it will kill them. It soon decomposes and then is 



1 Abbey, 1898 and 1899. 

 217 



