CONTROL OF POTATO PALE CYST-NEMATODE, GLOBODERA-PALLIDA, WITH A GRANULAR NEMATICIDE AND PARTIALLY RESISTANT POTATOES

The effects of oxamyl applied to the seedbed and growing partially resistant potatoes in controlling potato pale cyst-nematode, Globodera pallida, were assessed in eleven field experiments on sandy, peaty and silty loam soils in England from 1986 to 1988. Standardised procedures allowed valid comparisons to be made between data from the three experiments in 1987 and from the seven experiments in 1988. In soil moderately or heavily infested with G. pallida, oxamyl frequently increased tuber yields of susceptible cv. Desiree and of partially resistant potatoes and lessened crude nematode increase (Pf/Pi) significantly at some sites but not at others. Although 2.8 kg oxamyl ha-1 often increased tuber yields significantly, it was significantly less effective than 5.6 kg in controlling G. pallida at one site and at another site G. pallida increased more than in untreated plots. Potatoes partially resistant to G. pallida were more effective that oxamyl in controlling nematode increase at some sites but not at others. Combined use of oxamyl and partially resistant potatoes was generally more effective in controlling G. pallida than either measure alone. As measured by a 'control coefficient' (weight of tubers over 40 mm diameter (t ha-1) divided-by crude nematode increase (Pf/Pi)), the most effective integrated control of G. pallida was obtained by growing cvs Glenna, Morag or Sante in soil treated with 5.6 kg oxamyl ha-1.