Pearl millet as a rotation crop with flue-cured tobacco for control of root-lesion nematodes in Ontario

摘要

In Ontario, flue-cured tobacco (Nicotiana tabacum L.) growers routinely fumigate their soils to control root-lesion nematodes (Pratylenchus pénétrons Cobb). Studies suggest that planting pearl millet (Pennisetum glaucum L.) as a rotation crop may control the nematodes; winter rye (Secale céréale L.), the crop commonly grown in rotation with tobacco, is susceptible to the nematodes. In 2002, plots of forage millet (var. CFPM 101), grain millet (var. CGPMH-1) and winter rye were established at three sites and in 2003, tobacco was grown at these sites in non-fumigated plots where the rotation crops grew, except for a winter rye/fumigation treatment. The goal was to evaluate P. pénétrons populations and tobacco yield and quality in the millet rotations relative to the traditional rye-fumigation system. In 2002, initial P. penetrans populations assessed in the spring were similar for all treatments; however, the final populations and consequently the ratios of final populations/initial populations(Pf/Pi) consistently differed among treatments. The Pf/Pi ratios ranged from 0.07 to 0.79 for forage millet, from 0.18 to 0.94 for grain millet and from 2.33 to 21.65 for rye. In 2003, P. penetrans populations in tobacco plots previously cropped to either type of millet were comparable with those detected in fumigated winter rye plots. Compared with tobacco following rye without fumigation, tobacco yield was 14 to 51% higher following rye with fumigation, 19 to 70% higher following forage millet and 18to 65% higher following grain millet. Grade index was unaffected. Results indicate that pearl millet offers an alternative to fumigants for the suppression of P. penetrans population and provides equivalent gross returns.