Plant protection with inorganic ions.

Gradients of salts of the specific ion repellents for Meloidogyne incognita -- NH, K, Cl, and NO -- have been demonstrated to shield tomato roots from infestation in soil. The strategy of these greenhouse experiments was to interpose a salt barrier in a soil column between the plant roots and the nematodes. The relative effectiveness of the salts as a barrier to infective second-stage juveniles in a sandy loam was NHNO, NHCl > KNO > KCl. Some of these ions are beneficial to plant growth, and the results suggest that a new environmentally tolerable means of plant protection is possible.