Non-chemical control of replant disease, caused by Pratylenchus penetrans, in apple orchards in the Netherlands

Abstract: Apple replant disease is considered a problem of increasing importance in apple growing regions in Europe. In the Netherlands chemical soil fumigation (metam sodium) is the standard method to control replant disease in apple orchards in sandy soils. This disease is mainly caused by the root-lesion nematode Pratylenchus penetrans. The negative impact of chemical control on the environment and ground water makes the development of alternative control measures necessary. In a multi-year project, alternative and biological treatments were tested. The trials were carried out in an orchard were the apple trees were removed due to severe infestations of P. penetrans. The trial consisted of the following soil treatments: (1) growing of marigold (Tagetes patula); (2) growing of marigold followed by Anaerobic Soil Disinfestation (ABSD); (3) growing of black oat (Avena strigosa) followed by a ‘late’ ABSD treatment; (4) growing of a biofumigation crop, Indian Mustard (Brassica juncea); (5) compost amended in the soil; (6) black fallow (control); and (7) Chemical Soil Disinfestation (CSD; control). After the treatments the plots were replanted with apple trees (cvs. ‘Elstar’ and ‘Boskoop’). CSD, ABSD and Tagetes controlled P. penetrans significantly. There was no effect of biofumigation in controlling P. penetrans.