The effect of potato trap crops and fallow on decline of Globodera rostochiensis

Abstract

SUMMARYThe effects of 1 to 6 wk growth of resistant and susceptible potato cultivars on Globodera rostochiensis population decline were studied in pot and microplot experiments. In pot experiments, potato plants were hand pulled or killed with glyphosate herbicide at weekly intervals for 4 or 6 wk after shoot emergence. In microplot experiments, potato plants were killed with glyphosate herbicide weekly for 4 wk after shoot emergence. After 4 wk the number of viable eggs had declined more in pots where potato plants were grown (66–87%) than in pots of fallow soil (35%). Although decline in numbers of viable eggs under resistant and susceptible cultivars did not differ significantly, there was a trend towards greater decline under resistant plants. Duration of plant growth was positively correlated with decline in viable eggs when plants were killed with glyphosate but not when they were hand pulled. However, in microplot experiments using glyphosate, decline in viable eggs after 1 wk of potato plant growth (55%) was not different from that after 4 wk (57%). Numbers of viable eggs in fallow soil declined less 5 cm deep (34%) than 15 cm deep (50%). All of the viable eggs contained in cysts on the soil surface died within 5 months, probably due to high temperature.