What to do against nematodes?

摘要

Nematodes from the genus Meloidogyne, Pratylenchus, Ditylenchus and Paratylenchus are a problem in many vegetable crops in conventional and organic production systems. In organic rotations a high proportion of host plants (different vegetables, legumes, fertility building crops and weeds) compared to non-hosts (cereals) can increase the problem. A survey among 55 German organic farms during 2002-04 showed that in 87% of the area, yield reductions of 10% due to nematodes were observed. More then 50% of the nematodes were found in crops like carrots, celery and onions. Most of the problem fields had sandy soils. It is recommended that with a more careful rotational planning and better weed control, the problems with nematodes can be reduced. The growing of marigold as a nematode catch plant, the use of liming and fallow are also suggested. In field experiments the marigold species Tagetes patula was able to reduce nematode pressure by 90%. A high or optimum pH has good control effects on Pratylenchus crenatus..