ON THE CONTROL OF POTATO‐ROOT EELWORM (HETERODERA ROSTOCHIENSIS WOLLENW.) BY CHLORINATED PHENOL AND p‐m‐ CRESOL IN SOLUBILIZED FORM*

Abstract

Solubilized phenols and cresols, applied at the rate of 1s gal./sq.yd. at 5% strength on light sandy loam, have killed up to approximately half the population of potato‐root eelworm in the top 8 in of soil. When nematicide distribution was aided by rotavation on the same site, yields were approximately doubled compared with untreated areas. The eelworm population in the soil also increased, but not so much as that where no treatment had been applied.Under cold glasshouse conditions on light loam, high‐volume methods have greatly increased the yield of tomatoes compared with untreated plots, but the soil population of potato eelworm has also risen. 20 gal. to the square yard of 0·5%p‐m‐ cresol is better than 10 gal. of 1% by both criteria.There is evidence of a slow kill of cyst contents in soil samples stored in the laboratory.The high‐volume type of soil drench is shown to be highly effective under laboratory conditions. The importance of the initial water content of the soil is demonstrated. The superiority of the 20 gal. treatment over the 10 gal. one is confirmed.Investigations on kill in depth by very large applications of dilute nematicide in the same cold glasshouse have demonstrated the part played by the rate at which the material is applied. The degree of kill in the 6–12 in. soil layer is still inadequate.The practical applications of this type of nematicide are briefly discussed.

OBSERVATIONS ON THE CONTROL OF POTATO‐ROOT EELWORM (HETERODERA ROSTOCHIENSIS WOLLENW.) UNDER GLASS BY D‐D* AND SOLUBILIZED p‐m CRESOL†

“…It seems likely that in some soils, almost ideal conditions for D-D can be provided in glasshouses. By contrast, the performance of solubilized nematicides in the field is markedly inferior to that obtained in the laboratory (Stone, 1956). When combined treatments are used, the bulk of the larvae escaping treatment are still in the surface layers.…”

“…It has been shown (Stone, 1956) that, in practice, solubilized chemicals achieve a high degree of kill of potato-root eelworm in the surface layers of soil, but that the rate of kill falls off with depth. This mode of action is complementary to that of soil fumigants such as D-D. Peters (1955) has shown this on a laboratory scale, where he found no evidence of interaction between the two types of nematicide when they are used together.…”

The efficacy of fumigation of nematode‐infested soil following different methods of soil sealing

“…Increased nematode control by incorporation of a second toxicant in the surface of fumigated soil has been reported by several workers. Peters (1955) and Stone (1956Stone ( , 1957 improved control of potato cyst nematode with dichloropropane-dichloropropene by drenching the soil with a water-soluble nonvolatile chemical, p-m-cresol. Because of difficulty in handling this material and the large volume of water needed for drenching, the method has not been widely used.…”

“…Large amounts of water are needed for sealing the surface and as with rolling wetting is diflicult to practise effectively. Methods of seahng chemically have included drenching the soil surface with solubilised ;7-w-cresol (Peters, 1955;Stone, 1956Stone, , 1957 and incorporating dazomet in the surface layer (Seinhorst, 1973;\yhitehead et al, 1973). This paper reports the effect of sealing fumigated soil surfaces with easily applied resin sprays and of incorporating dazomet with the Rumptstad Combiject during the injection of a liquid fumigant.…”