Observations on the control of the stem nematodeDitylenchus dipsaciof tulips with hot-water or thionazin treatment

Abstract

SUMMARYStem nematode (Ditylenchus dipsaci (Kühn) Filipjev) was controlled by either hot-water or thionazin treatment of lifted tulip bulbs, but some nematodes survived all the treatments. Hot-water treatment at 115 °F (46.1 °C) for one hour was less damaging to the bulbs than treatment at lower temperatures for longer periods of time, and treatment in July was less harmful than treatment in September; but the growth, of all except the most tolerant cultivars was checked so severely that the method would have only a limited use in commercial tulip production. Dipping the bulbs in the normal strength of thionazin, 2300 ppm, or in double this strength (4600 ppm), had no adverse effect on growth and flowering during the year after treatment, and the performance of bulbs treated in July or September was similar.