This season is shaping upto be one of the worst for Potato Cyst Nematode (PCN) damage and growers mustidentify affected areas now in order to plan future control strategies.
That is the warning fromleading agronomy firm Hutchinsons, which sponsored a new event in Scotlandearlier this month examining how growers can tackle the mounting PCN threat.
Thefirms potato specialist Darryl Shailes says there have been massivedifferences in PCN treatment response trials this year, with up to a 50% reductionin canopy cover recorded in untreated plots compared with treated crops.
Itsdefinitely a big year for PCN. The mild and wet weather we had earlier in theyear resulted in a lot of soil moisture, good egg hatch and a lot of PCNactivity.
Therehas been considerable juvenile activity in particular, and its these whichcause the damage. Juveniles get into the roots and feed off the plant resultingin retarded growth and potentially a big loss of yield. A 50% reduction incanopy is likely to result in more than 50% loss of yield by the time we get toharvest.
MrShailes says now is a good point in the season to inspect crops for signs ofPCN damage, as visual effects are most pronounced.
Ascrops get into flowering patches of retarded growth may be easier to identify.If you suspect PCN, dig up a few plants and look for the cysts which are juststarting to form, he advises.
Cystswill be cream coloured bead-like objects attached to the roots.
IfPCN is found, Mr Shailes acknowledges there is little that growers can do interms of control this season, but says that adding a little extra foliarnitrogen, phosphate and trace elements to affected crops may help mitigateyield impact by boosting ailing growth.
Itllnever turn it into a great crop, but may at least keep plants going a bitlonger. The most important action is to record any affected areas andcross-check them with your regular PCN mapping.
Ifyou do have patches of PCN, they need to be managed proactively with catchcrops or maybe soil sterilants, before growing potatoes on that land again.