Nematode, Dagger

Dagger nematodes live in soil and remain invisible to your eye, making this pest insidious compared to foliar diseases. The real concern with dagger nematodes in Western Washington, particularly in blueberry fields, is that they transmit tomato ringspot virus, which causes far more damage than the nematodes themselves. You won't see wilting or obvious root injury from the nematodes alone; instead, watch for stunted plants, yellowing leaves, or poor fruit production that correlates with virus presence. Soil sampling from December through March is your best window to detect them before they establish.

The critical thing to know is that dagger nematodes thrive in soil rich with moisture and vulnerable host plants, and virus transmission happens silently during spring and fall when soil conditions are optimal for nematode activity. Your one major move is to test soil before planting blueberries or other susceptible crops; if nematodes are detected, plant tolerant cultivars like Northwest, or use cover crops and fallow periods to disrupt the nematode life cycle. Because dagger nematodes have a narrow host range compared to other root-feeding types, choosing the right cover crop strategy can effectively starve them out before they transmit virus to your crop.