DAMAGE TO FLUE-CURED TOBACCO BY THE NEEDLE NEMATODE LONGIDORUS ELONGATUS
The ectoparasitic nematode (Longidorus elongatus (de Man 1876) Thorne and Swanger 1936) was associated with severe stunting of flue-cured tobacco (Nicotiana tabacum L.) at Delhi, Ontario in early June 1971. Foliar applications of the nematicide Vydate ((S-methylcarbamoyl)-N-[(methylcarbamoyl oxy)] thioformimidate) to the stunted plants reduced the number of L. elongatus in the soil around the roots but did not improve plant growth. A pot test in a greenhouse indicated that flue-cured tobacco, rye (Secale cereale L.), and winter wheat (Triticum aestivum L.) were poor hosts for the nematode whereas sweet corn (Zea mays L.) and sorghum (Sorghum vulgare Pers.) were good hosts. Apparently, in the field the small numbers of L. elongatus that had been subsisting in the soil had multiplied to damaging levels on a crop of sorghum grown in the previous year. Because of the rare occurrence of Longidorus spp. in soils of the tobacco-growing areas of Ontario and the crop rotation and soil fumigation in use by most growers of flue-cured tobacco, it is unlikely that any specific control measures will be required to prevent damage to tobacco by L. elongatus.