Early crop root destruction for management of tobacco cyst nematodes.

Prompt tillage after crop harvest was investigated as a cultural control for the tobacco cyst nematode, Globodera tabacum tabacum, on stalk-cut broadleaf cigar wrapper tobacco. Stalk stumps and roots remaining after harvest were destroyed by tilling immediately or from 2 to 6 wk after harvest in field experiments over 4 yr. Cyst nematode Pf/Pi ratios ranged from 0.65 to 1.62 when plants were tilled immediately after harvest and 1.13 to 5.88 when tillage was delayed. Nematode population development was monitored by inoculating plants in pots placed in fields with J2 in eggs and sampling over time (8 to 18 wk). Three generations per year were observed, and G. t. tabacum generation time was as short as 6 wk for each generation. Destroying stalks and root systems remaining after harvesting stalk-cut broadleaf cigar wrapper tobacco removes the host to preclude development of nematodes at the end of the second and entire third generation. Early tillage resulted in consistently lower tobacco cyst nematode populations than allowing viable roots to remain in fields for an additional 8 to 18 wk. This management tactic reduces the need for nematicide application to slow nematode population increases over time and can reduce losses due to infection by G. t. tabacum.