The placement, fate and effectiveness of granular nematicides in potato beds infested with the potato cyst nematode Globodera pallida (stone)

• Main Author: Woods, Simon Roger
• Published: Open University 1997
• Subjects: 631.8; Agricultural chemistry & fertilizers
• Online Access: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.298980

The chemical control of the potato cyst nematode (PCN) by granular nematicides when applied and incorporated into potato seed beds was investigated to assess problems connected with incorporation using bed cultivation machinery. Fluorescent tracer granule work using a range of granular nematicide incorporation methods suggested that differences exist between the incorporation methods in terms of placement of the fluorescent granules in the planted potato bed. Incorporation of tracer initially by a bed tiller followed by a second incorporation by a stone and clod separator produced a distribution of tracer greater than 40cm deep in the planted bed. Incorporation of tracer by a stone and clod separator with application of tracer halfway up the first web produced concentrated bands of tracer in the sides of the planted bed. No visible differences in tracer distribution occurred between other treatments. The differences observed between incorporation techniques during the fluorescent tracer granule work were shown not to be important in terms of PCN control or yield in the first year's field experiments. The second year of field experimentsa ssessedth e incorporation of the granular nematicide Vydate (10G) before, during or after stone and clod separation of potato beds. These field experiments suggested that timing of nematicide incorporation in relation to stone and clod separation had no effect on potato yield or control of PCN. As in the first year's experiments, significant differences occurred between plots treated or not treated with a granular nematicide, but not between incorporation methods. Work describing the field concentration of oxamyl immediately after planting showed similarities to the distribution of tracer granules observed in the soil hall studies. The subsequent distribution of oxamyl 3 weeks after planting showed no redistribution of the nematicide in the potato bed. The depth of potato planting is thought to be responsible for the uniformity of PCN control and crop response to nematicide treatment regardless of incorporation method as seed was planted below the nematicide treated layer. Evaluation of a diagnostic kit used for detecting oxamyl in soil showed that the kit was well suited for this purpose and its use is discussed in the light of the findings of this study.