Abstract

A pot experiment indicated that in a soil with a replant problem some raspberry cultivars (e.g. Glen Moy and Glen Clova) grew better and showed smaller growth responses to a fungicide (benomyl) and a nematicide (aldicarb) treatment than others (e.g. 'Malling Promise' and 'Malling Jewel'). However, although untreated 'Glen Moy' grew slightly larger in a field trial than untreated 'Glen Clova' and 'Malling Jewel', all 3 cultivars showed similar large increases in cane growth in plots treated with dazomet. A crop rotation in which raspberry followed a 3-year break of cereals, strawberry or fallow did not improve the growth of the replanted raspberry compared with raspberry following raspberry. Nor was the increased growth response to replanting treatments with either full or half rates of dazomet influenced by crop history. Populations of Pratylenchus penetrans were low after planting treatments (-1 soil), and, from the lack of a growth response to aldicarb treatments, they appeared to be causing little or no damage in either field trial. Also, there was little growth response to an additional nitrogen treatment. Hence, the main part of the dazomet effect is attributed to control of unknown soilborne fungi. Pot tests indicated that the beneficial effects of dazomet treatment persisted only for 1 or 2 years.