AbstractIn an attempt to evaluate the occurrence and economic importance of plant-parasitic nematodes in organic farming in Germany, a survey was conducted with the main emphasis on vegetable and cereal production systems. For vegetables, the survey included quantification and identification of plant-parasitic nematodes in soil samples and a questionnaire for growers querying production factors and damage levels. For cereals, the survey focused on quantification and identification of plant-parasitic nematodes in soil and plant samples. Overall, Pratylenchus and Tylenchorhynchus were the most prominent nematode genera under both production systems with an incidence of over 90% of the samples. Meloidogyne was detected in 51% of the samples in both systems. Other nematode genera showed differences between the two production systems. In production systems with a high frequency of vegetables, Paratylenchus was detected in 56% of the samples and Heterodera in 15%, whereas in rotations with a high cropping frequency of cereals, incidences of plant-parasitic nematodes were 56% for Heterodera, 47% for Trichodorus and 45% for Paratylenchus. Yield losses could exceed 50% on carrots, onions and cereals and were most pronounced on sandy soils. In many cases, nematode problems started 5 to 10 years after conversion to organic farming. The survey indicated that plant-parasitic nematodes are widely spread in organic farming in Germany and can cause severe damage which may result in complete loss of the crop.
Occurence of plant parasitic nematodes and factors that enhance population build-up in cereal-based cropping systems in Uganda
