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