Infestation pattern of foliar nematode,Aphelenchoides ritzemabosi(Nematoda: Aphelenchoididae), on boysenberry

Abstract

Abstract Infestation behaviour of the foliar nematode, Aphelenchoides ritzemabosi on boysenberry (Rugus strigosus) plants was studied in 2 commercial gardens at Motueka, South Island, New Zealand. Nematodes overwintered in the pruned stubs of old fruited canes, then invaded primocanes (new growth produced before winter) in early spring when plants broke dormancy, causing a brown streaking and epidermal peeling on stems. The nematode feeding site was directly beneath the cane epidermis, and conductive tissue remained protected by tough cork cambium. In well managed gardens infestation was restricted to the lower 1 m of the plant regardless of population density. Despite infestation, yields were high and no plant death, cane die-back, or bud death was noted. One garden had a disease symptomatic of crown gall, and a close association was found between the distribution of cane galling and nematode infestation within plants. Gall tissue yielded very high numbers of A. ritzemabosi. The behaviour of the nematode in relation to crop husbandry practices is considered in this paper and the need for cultural control methods is discussed.