CULTIVATION AND TECHNOLOGY New Potato Cyst Nematode policy forces growers to look ahead story.’ To be able to deal with mixed populations, Hoogland has gained experience with using potatoes as a trap crop. For this purpose, he uses undersized seed, which he plants with an old bulb planter. You have to make a few adjustments, because the machine wasn’t exactly built for this type of work. The distribution of tubers in the longitudinal direction is therefore not very good. The distance between the rows – 25 cm – is okay, but the bed is only 120 cm wide. In order to work as economically as possible, Hoogland drives his planting machine with one wheel across the previous bed. ‘This is not ideal, but it works,’ he concludes. After 40 days, he must kill the crop with Roundup. That is a precise job, because the trap crop is between the regular seed. Nevertheless, the Frisian farmer thinks it is worth the trouble. Wherever he used this same working procedure earlier, he now has seed potatoes growing again. Problems with `Saturna plots’ Also on the farm of Jelle and his son Bart Bruin, in the village of Bant, infections are definitely the number one problem. They know exactly which nematodes they have in the fields. In the last couple of years, they have expended a lot of energy in clearing up the infections in the plots they have bought over the past ten years. There were quite a few ‘Saturna plots’ among them, as they call them. Or plots where Saturna was regularly grown because of its resistance to rostochiensis. That was not always thought through, because Pallida was able to develop without any problem. ‘We have taken drastic steps to get these plots clean again’, said Jelle Bruin. ‘Often even by using a method of applying soil decontamination and NEW POTATO CYST NEMATODE POLICY IN BRIEF The standard size of the soil sample is increased from 600 to 1,500 ml per hectare. This increases the possibility that an infection is found. On plots with a clean history, growers may continue to send in 600 ml samples; this means no potato crop for 6 years, or no live or dead cysts in the last test, or no live cysts in the past two tests. If a live cyst is found, a larger area will be declared contaminated. The demarcation (previously buffer zone) increased from 6 to 16 metres. There must be a minimum of 27 metres between two infections, so that there are going to be fewer barcodes or crossings. If you are officially declared infected, this applies to everything in the plot. When an infection is found, new test sampling may only be carried out after six years, or three years after applying decontamination measures. This means that the business must revert to a rotation schedule of 1:4. Loss of seed potato status if live cysts are found in attached soil. The definition of a ‘lot’ is not yet clear. For the moment, brushing or washing gives no consolation for being allowed to export the lot in question. New study must determine whether this measure works well. Instead of detection of bad spots by helicopter, annually, 0.5% of the area of consumption potatoes is tested every year to prevent Potato Cyst Nematode infections. ‘We have taken drastic steps to get these plots clean again. Often even by using a method of applying soil decontamination and the cultivation of resistant varieties’, says seed potato grower Jelle Bruin. the cultivation of resistant varieties. However, we know from experience that soil decontamination is not enough if the infection is severe.’ In recent years, the Bruin family has expanded considerably in cultivating starch varieties with Pallida resistance. They have looked for these varieties and are now growing them for a few trading companies. It gives them more flexibility and makes it easier to lease plots. Jan Hoogland has been growing a few hectares of Seresta for a few years, which he rotates in fields where Pallida was found. Both growers see that there is a key role for resistant potato varieties where controlling Potato Cyst Nematode is concerned. They are worried, however, about availability. There is an enormous interest in them and the supply is limited. Moreover, there is the question as to whether the cultivation of starch potatoes in the Netherlands can continue to exist at its present number. 12 Potato World 2010 • number 3 Pagina 11
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