Virus prevention in seed potatoes is becoming a bigger challenge every year. This is partly due to the further narrowing of the resources package for lice control. Ko and Wim de Kraker from Zaamslag have now adapted their strategy to this. By starting with Olie-H early and providing their field sprayer with an extra row of nozzles, they give lice and virus less chance.
Every year fewer products are authorized to combat aphids that infect crops, such as potatoes, with viruses. However, the brothers Ko and Wim de Kraker can deal with this soberly. They have traditionally been used to rowing with the oars they have and adjusting where possible. Also in seed potato cultivation, although that is not always easy. "Standards are strict, the choice of insecticides is limited and aphids appear to be less sensitive to some pyrethroids. The effectiveness of aphid control with these agents decreases as a result," the seed potato growers know.
Taking the above challenges into account, the brothers are now opting for a different approach in their 40 hectare seed potato cultivation. The adjusted strategy was determined in consultation with cultivation advisor Karel Steijaert of CZAV from Wemeldinge. The first measure remained unchanged: starting with clean starting material. "We always purchase high-quality S material," says Ko. "Then we can check these again and we will immediately have our own virus check, before we can hopefully deliver the seed potatoes virus-free in class SE."
Start earlier with Olie-H
The next and modified measure is to start earlier with the use of Olie-H. "Lice flights start earlier, because of the changes in the climate and cultural landscape. Lice are often present in large numbers on and around the seed potato plots before the emergence of the potato plants," experience the seed potato growers in Zeeland. "Our advice is to carry out the first spraying with Olie-H as soon as 30% of the plants have emerged," adds Steijaert. "The more evenly the crop emerges, the more effective the first treatment is. You protect more plants and less product is lost."
The seed potato growers do their best to achieve the desired uniform emergence for their crops, although this is not always easy. "The soil conditions in the spring have a lot of influence," explains Ko de Kraker. "Especially in dry weather and after a mild winter, the emergence can be uneven. In order to control this, we carry out the definitive ridge construction immediately during planting. In our experience, this gives a more even emergence than late milling."
Extra nozzles
To make the first spraying(s) with Olie-H even more effective, the brothers have equipped their young CHD sprayer with a set of extra nozzles. These are therefore 25 centimeters apart on the boom instead of the more usual 50 centimeters. "The advantage of this is that for spraying on young, newly emerged plants you only need to turn on the nozzles directly above the middle of the ridges. You don't have to spray between the rows yet," says Wim de Kraker. "The early spraying is therefore not only more effective, but also more efficient. We have had experience with this for two seasons now and we like it very much."