Variation in hatch among pathotypes of the potato cyst nematodes, Globodera rostochiensis and G. pallida, in response to potato root diffusate from Solanum spp. I. Preliminary assessments to establish optimal testing conditions.

Potato cyst nematodes (PCN) hatch in response to the presence of root diffusate produced by host plants. Potato root diffusate (PRD) contains hatching factors that stimulate differential hatch between the two PCN species (Globodera rostochiensis and G. pallida) throughout the growing season. In order to clarify the role of PRD in wild potato clones resistant to PCN, a series of trials established optimal test conditions using a range of PCN populations on a representation of Solanum species (Solanum sanctae-rosae, S. sparsipilum, S. gourlayi, S. acaule, S. oplocense). Dilution tests showed that half strength PRD consistently stimulated highest levels of nematode hatch. PCN populations were treated with PRD collected weekly throughout the trials, mimicking the natural release of chemical stimulants from growing potato roots. Whilst the G. rostochiensis Ro1 population showed no variation in hatch, other populations displayed differences in hatch in the presence of the different Solanum PRD. This may reflect the different coevolutionary histories of nematodes and their Solanum hosts in South America. [ABSTRACT FROM AUTHOR]