Basal fertiliser application method, tuber initiation nitrogen, foliar NPKand the tolerance of potatoes to infection by the potato cyst nematodes Globodera rostochiensis and G-pallida

The effects of broadcast granular, placed liquid and foliar fertilisers on the tolerance of potatoes to infection by potato cyst nematodes were invest igated. The tolerance of the potato cv. Pentland Dell was not significantly improved by fertiliser application type but placed liquid fertiliser, with or without foliar applications, increased the concentrations of N, P and K measured in whole plant dry matter of PCN infected plants. The tolerance o f the potato cv. Sante was not statistically improved by altering the balan ce of fertiliser nitrogen applications between planting and tuber initiatio n or by applying foliar nitrogen. Nitrogen applications of 120 kg N ha(-1) at planting and a further 120 kg N ha(-1) at tuber initiation supplemented with foliar N, however, achieved a larger tuber yield than the same nitroge n programme without foliar N and gave a significantly greater yield than th e application of 240 kg N ha(-1) at planting plus foliar N. The emergence o f both cultivars was delayed in the absence of oxamyl. N, P and K concentra tions within whole plant dry matter were significantly higher in plants fro m oxamyl treated plots and both N and K concentrations were significantly i ncreased by increasing the quantity of N at planting, at 56 DAP. Splitting the fertiliser N between planting and tuber initiation appears to be import ant in maintaining the availability of this nutrient to PCN infected plants throughout the season.