The onions are growing so protect them from harm

After a wet and cold spring and early summer, the onions are currently growing well. At the same time, thrips are lurking and downy mildew is spreading in more and more fields. In this cultivation journal, Kees Jacobs discusses the points to consider to keep the crop in condition for good production.

"If you drive past it seems like a lot, but if you stand in the middle of a plot, you see that the onions are thin or irregular in many plots. But fortunately we now have higher temperatures and still the occasional shower. the onions have been added considerably and they are now growing well." In a few sentences, Kees Jacobs, onion expert at Syngenta Seeds, aptly summarizes the situation as he finds it in practice. And he immediately adds that there are major differences. "There are also very beautiful plots, relatively many in Flevoland and the North, but in every region you have plots with a story." For the coming period, as far as Jacobs is concerned, attention must be fully focused on optimal growth of the crops. "It has to be done in the coming month. The weeks ahead are crucial for production."

Stay alert for thrips
The peak of problems caused by the onion and bean fly is now over, although Jacobs suspects that the onion fly is still active. "But the plants are now so big that they no longer collapse from a little bit of eating damage. I do think that eating spots could be entry points for fungi or bacteria, but I don't think that has ever been investigated." The advisor says that there is also local damage due to nematodes, but the most current problems are problems with thrips. Jacobs: "I have recently seen plots in several regions where control has been too careless. Then you peel open the pipes and the larvae come towards you, but no spraying has been done yet. The following applies to thrips: as soon as your larvae If you find it, spray immediately. Don't forget that it takes a few days for the products to work. And with a warm weekend ahead, there could be a peak in reproduction."

Mildew is the biggest concern
What the onion expert from Syngenta Seeds is currently most concerned about is downy mildew. "I hear from fellow advisors and from the trade that they find it everywhere and that the fungus is spreading locally. It started in the onion onions, but now you also see it in sowing onions. In Brabant there are examples of plots that are still have never dried properly and where the downy mildew situation is quite serious." Jacobs thinks that, given the weather forecast with occasional showers, conditions for downy mildew will remain favorable for the time being. "Inspect your crop regularly, twice a week as far as I'm concerned. And realize that if you find an affected plant, its neighbors are almost certainly already infected. Because downy mildew has a long incubation period. It can Current temperatures take about one and a half to two weeks before you see it. And spraying can only be done preventively, so keep your schedule closed."

What to do with MH later?
It still seems far away, but the very earliest plots will be ready for MH spraying at the beginning of August. Jacobs: "For plots that are thin or irregular, you will soon have to decide whether you are going to store the onions, for how long and whether MH spraying is useful. How vital is the crop and what is the chance of many thick necks causing problems? in storage? Or is there perhaps a lot of disease in the plot? These are all factors that can influence your decision about storage and the usefulness and necessity of MH spraying. I always advise not to make that decision on your own together with someone else, for example your cultivation advisor. He or she looks a little more objectively."

The last tip that Jacobs wants to give is mainly future-oriented: August 29 is again the national Onion Day of the Onion Information and Knowledge Center (UIKC) in Colijnsplaat. "The best event to stay informed of all new developments in and around onion cultivation. Syngenta is also there with information about our varieties, crop protection products, including biologicals and our special services such as the InterraScan soil scan. We would like to welcome you." Also see this link.