Title: Chemical control of nematodes: efficiency and side-effects
Headings: Chemical control of nematodes: efficiency and side-effects
Chemical control of nematodes: efficiency and side-effects
S.R. Gowen
Introduction
Chemical control of nematodes
The demand
Efficacy
TABLE 1
Nematicides currently available on world markets
TABLE 2
Examples of recommended nematicidal dosages and treatments for some important crops1
Side-effects
Future developments
References

Content: Oxamyl, a systemic compound that is translocated basipetally, is the only commercial product that is used as a foliar treatment, but its use as a liquid formulation is restricted in many countries for toxicological reasons. There are several nematicides that can be used effectively for nematode pests of annual crops (van Berkum and Hoestra,1979), but there appears to be little prospect for management of nematodes in many susceptible perennial crops without repeated application of nematicides (Tables 1 and 2). Only in certain cases will such treatments be justified economically. Since the discovery and wide-scale use of fumigant nematicides 50 to 60 years ago, a number of products and formulations (Table 1) have been developed for use against several nematode pests, and these are available in most regions of the world (Hague and Gowen, 1987). Only in comparatively recent times have the dangers associated with the manufacture and use of these products become apparent. This has resulted in restrictions on use and sometimes withdrawal from the market. It seems that the age of the traditional fumigants and nematicides has passed, and the opportunity for managing nematodes with synthetic chemicals with broad biocidal activity is declining. The development of new classes of nematicides with novel activity, that are effective when used in soil or applied directly to crops and are environmentally benign and specific to target pests, is perhaps an idealistic hope. Such compounds will, by definition, require considerable research effort, and if they are specific only to certain nematodes are unlikely to be considered an economic proposition for the traditional agrochemical company. Chemical control of nematodes
The demand
The elimination of nematodes from some crops is essential for certain export requirements, particularly of high-value horticultural products.