Impact of Pratylenchus penetrans on Establishment of Red Raspberry.

The plant-parasitic nematode, Pratylenchus penetrans, is a major constraint to red raspberry (Rubus idaeus) production. To determine the impact of P. penetrans on the establishment and productivity of eight raspberry cultivars, R. niveus, and R. leucodermis, plants were grown in fumigated and nonfumigated soil. Then, soil and root populations of P. penetrans and plant productivity (vigor, cane height, biomass, and yield) were monitored over 2 years. In a separate experiment, the role that soil type plays in mediating P. penetrans populations and raspberry establishment was investigated. At 6 and 12 months after planting, population densities of P. penetrans were lower in fumigated than in nonfumigated soil; this trend continued 18 months after planting. All cultivars and R. leucodermis were found to be extremely susceptible to damage caused by P. penetrans. By the end of the experiment, yield was the most sensitive indicator of plant productivity among cultivars, with losses in nonfumigated soil ranging from 63 to 100% of those observed in fumigated soil. However, there was no difference in the productivity of R. niveus plants grown in nonfumigated versus fumigated soils. Results also indicated that the damage potential of P. penetrans was greater on sandy loam versus silt loam soils. The total plant biomass of 'Meeker' raspberry was 46% lower in a sandy loam soil containing P. penetrans compared with soil without P. penetrans; this trend was not observed consistently in a silt loam soil. Despite the fact that soil fumigation is increasingly more limited by regulations, this study shows the utility of fumigation in reducing P. penetrans populations for a sufficient period of time to ensure that newly planted raspberry seedlings can become successfully established.