SCIENTISTS are questioning the possibility of a link between nematodes and the incidence of scab in potatoes, after studies in Norway linked the root lesion nematode Pratylenchus penetrans to common scab. Food and Environment Research Agency (Fera) nematologist Tom Prior said it was not yet known if the presence of these nematodes can be linked to the incidence of scab in UK crops. “The nematodes can cause scab-like symptoms. Pratylenchus penetrans is native to the UK, is particularly pathogenic and has more than 350 recorded host crops, including potatoes. This nematode penetrates, lives and feeds in the root and the damage thresholds on potato are reported as low as 1-2 nematodes/g soil,” he said.