Many overwintering aphids have died due to the severe frost of the past week. This will reduce the problems with PVY in the coming season. That said researcher Klaas van Rozen of Wageningen UR on Tuesday evening during a webinar organized by the Seed Potato Academy and ZLTO.
“We had a few days with -7 degrees. This leads to a significant decrease in the number of aphids. A lot of people die at -3. ” The lice can survive at temperatures around freezing point. It will not be completely aphid-free. “The eggs do hibernate in the winter host. They will come later. ”
The fact that more fields of greenery enter the winter as a result of NKG or wintergreen fertilizers does not have to be a threat to the survival of aphids, Van Rozen said. “If the green manure is incorporated, the leaves die off. The aphids die, they are very delicate bugs. I don’t expect any more problems from those lice. ”
Within the Seed Potato Academy, several tests have been conducted in recent years in the field of aphids and virus. Among other things, it was investigated what the effects are of different spraying schedules. However, no unequivocal advice emerged from this, said Johnny Remijn. Looking at the results in the first selection round, only the untreated field stood out negatively. So doing something is much better than nothing. But no major differences were visible between the different drug combinations. It remains difficult. ”
Virus pressure is also high in Belgium
The virus pressure is also high in Belgium, Kürt Demeulemeester, arable research leader at Inagro, Belgium, said during the webinar. And that while, just like in the Netherlands, the range of resources is getting narrower. In 2018 and 2019 there were many problems with PVY in the Belgian starting material and there were more class decreases in the follow-up check. In 2019, 30 percent of the downgrades were due to virus. “I don’t have the figures for 2020 yet, but I expect the same picture.”
Trials have also been carried out in Belgium with alternative aphids, such as peppermint oil, or straw covering over the potato ridge. Both methods showed no added value in the demo fields, according to Demeulemeester. Mineral oil, on the other hand, worked well.
The potato virus Y causes considerable economic damage in potato cultivation. The number of batches infected with PVY during follow-up has increased sharply in recent years. PVY is transferred by aphids from sick to healthy plants.
