Many potato growers are still not testing landintensely enough for potato cyst nematode (PCN), warns John Keer fromindependent agronomy and analysis firm Richard Austin Agriculture.
Soilsampling is vital to identify PCN hotspots and develop an effective nematicidestrategy, and the optimum testing intensity should be one sample per hectare,he says. Most forward-thinking growers are already testing at this intensity,but there are still many in the industry only taking one sample per field orone sample per 4ha. Thats simply not enough and means you can easilyunderestimate or miss problems completely.
Robustsoil sampling is even worthwhile on land you may think is clean and free fromPCN, he adds.
Theoverall cost of GPS sampling and PCN analysis is around 30/ha, which isnt alot on a crop thats costing over 6,000/ha to grow, yet the impact of a PCNproblem can be massive if you get it wrong.
Hutchinsonsroot crop specialist Darryl Shailes says even low levels of PCN can have asignificant impact on crop health, increasing susceptibility to key diseasessuch as alternaria and ultimately reducing yield and tuber quality.
Heagrees that a testing intensity of one PCN test per hectare should be aimedfor, with the soil sample taken from an aggregate soil sample made up of asmany individual soil cores as practically possible. The more soil samples youtake, the better youre chance of identifying any PCN hotspots. Ideally we aimfor 50 soil cores per hectare.
MrShailes says soil sampling and PCN testing forms just part of a long-termintegrated plan for protecting land for future potato growing, alongside otherfactors such as variety choice, bio-fumigation, nematicide choice and croprotation. Controlling PCN is not just about the effects on the following crop.Good potato land is expensive to buy or rent and not easy to find, so we allhave a responsibility to protect it as best we can for the future.
Pressureon the existing armoury of nematicides also means it is vital that products aretargeted as accurately as possible to keep on top of any potential threat, DrKeer adds. Weve all got to ensure PCN levels are kept as low as possible togrow the crop sustainably in the future. We believe that PCN sampling once ahectare gives the optimum balance between time, cost and providing enoughinformation to control PCN effectively.