On the Development of the Citrus Nematode (Tylenchulus semipenetrans COBB) on Roots of Citrus Seedlings

Abstract

The citrus nematode and its development and multiplication on seedling roots of trifoliate orange, Citrus junos, and C. natsudaidai were studied. The largest number of nematode larvae and adult females was counted on the roots of C. natsudaidai followed by C. junos, and the smallest number was counted on the roots of trifoliate orange. From these results, it is considered that the trifoliate orange is not so resistant nor tolerant to citrus nematodes as reported so far from U.S.A., but appears to be somewhat unfavourable for nematode multiplication compared with the other two citrus species employed in this experiment. Between 20-26°C of soil temperature at 5cm deep, the egg-laying of the nematode takes place within 5-6 weeks on C. natsudaidai and C. junos, and somewhat later on trifoliate orange. Since the optimum temperature for the multiplication of this nematode appears to be at a range of 20-33°C under the condition of volcanic ash soil in Kanagawa Prefecture, it is considered that the period during which this nematode can multiply in the field is from late April to the end of September in this area.