New Potato Cyst Nematode policy forces growers to look ahead CULTIVATION AND TECHNOLOGY PLANT PROTECTION SERVICE INCREASE IN INFECTED AREA IS STILL AN UNKNOWN FACTOR With bigger samples and broader definitions, it is plausible that the infected area will become greater than the current 5,000 hectares in the coming years. How much bigger, Frans Janssen, sector manager for arable crops of the Plant Protection Service cannot say. ‘You can carry out several calculations based on the different factors. For example, the effect of a bigger sample is calculated at a 12 percent increase and the broader definitions at over 50 percent. The longer infection period also provides an increase. But the ultimate effect is not a matter of simple calculations. What you see is that growers often have tests carried out on a voluntary basis and are taking action. As a result, the infection pressure is decreasing and the increase in the number of infections is stagnating.’ Without mentioning real figures, NAK-Agro was able to say that the number of test samplings had increased by one third. It will cost money Although Bruin and Hoogland have done all they could to get their soil clean on the basis of intensive sampling, they expect that the new Potato Cyst Nematode policy is going to cost a lot of money. ‘If you are now officially declared infected, you have a greater problem than under the old rules’, says Bruin. ‘If, under the new rules, one live cyst is found, you have lost 1.5 hectares straightaway. In addition, we are now going from a 1:3 to a 1:6 rotation schedule. That’s because we lease out our land to bulb growers once every six years. You can, of course, take measures and start growing seed again in the fourth year, but that turns your complete cropping plan upside down.’ Hoogland is not going to change his crop rotation schedule. He would rather use that year lost to the cultivation of seed potatoes for growing a resistant consumption potato variety. ‘But you must then be lucky enough for the test to show that there is only one nematode type. That’s why I think it so important that, on a voluntary basis, an intensive test is carried out straight after the harvest, including the determination of types of nematode. Only if you have that information, can you start combating the infection.’ Risk perception Other growers also see that need. Last year, significantly more voluntary testing was carried out, the advisors noted. Without mentioning real figures, NAKAgro was able to say that the number of test samplings had increased by onethird, for example. Beyond that, the growers are taking the trouble to remain within the 600 ml of test sampling. The Dutch General Inspection Service for Agricultural Seed and Seed Potatoes (NAK) expects approximately 2000 ha more registrations before 1 July for official test sampling than in previous years. There is one part for which the seed potato growers cannot prepare themselves yet. If, under the new rules, one live cyst is found in attached soil, a lot of seed potatoes will be declared contaminated. It is not clear what exactly a lot is and – in simple terms – how many boxes a grower will have lost. For that the Plant Protection Service (PD) will have to take a decision before 1 July. ● Egbert Jonkheer Potato World 2010 • number 3 13 Pagina 12
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