The earliest seed onion plots are ready for MH spraying at the end of July; the masses follow in the weeks that follow. Onion experts Kees Jacobs and Michiel van Mol advise growers to keep a close eye on the spraying conditions. "In changeable weather you can just miss the most beautiful moment."
"In recent years we have had to deal with drought and heat, but this season we have to deal with wetness." Michiel van Mol summarizes it succinctly. He and his colleague Kees Jacobs see that the seed onions are generally in good shape. The backlog due to the cold spring has partly been made up due to the growing weather of the past period. And the thrips are well manageable this year. "We find a few everywhere, but thrips don't feel comfortable with precipitation and relatively low temperatures. The onions now grow well and are not stressed. And that is the best weapon against damage from thrips."
duality
Yet there are also differences. "In the Southwest, the onions haven't looked so good in years," Jacobs says. "However, in other parts of the country, hail, drift damage and excessive precipitation have caused localized ambivalence. We also see damage from nematodes and in all onion-growing areas there have been cases of damage due to excessive use of soil herbicides. On plots where these conditions are present. The timing of the MH spraying is difficult again." According to the onion experts at Syngenta Seeds, growers who are struggling with double crops should first decide whether the batch is suitable for longer storage. And if one decides to apply MH, the optimum spraying moment must be matched to the most developed onions.
The right spray moment
The grower has several points of reference for the timing of the MH spraying. "The most commonly used criterion is that 10% of the onions have been ironed," says Van Mol. "The ratio of the diameter of the sphere and the neck is also used. It must be at least 3 to 1. And if there is still doubt, you can squeeze the neck, just above the sphere. It should feel soft. " According to Van Mol, the latter criterion is particularly useful if there is doubt as to whether the onion has been ironed naturally or by the wind. In addition to the timing, good absorption of the MH is also crucial for the germination inhibition. “Always spray with plenty of water,” advises Jacobs. "At least 500 liters per hectare. And spray at a time when the crop remains dry for at least 10 hours. That could be the biggest challenge this year. After the MH spraying, you just need a long period of solid dry weather You may also want to consider adding a stitcher." If you are nevertheless surprised by a shower within a few hours, you will be faced with a difficult decision. "If you want to keep them for a long time, I would repeat the spraying," Jacobs advises. "Otherwise, you'd better say goodbye before Christmas."
fungal weather
After the MH spraying, the onions must remain green and vital for at least another 14 days so that the MH can enter the bulb via the sap flow. "So just continue with disease control," says Van Mol. "But you have to do that this season anyway. In previous years it was insect weather, this year it is a feast for fungal diseases. And we are also seeing leaf spots again. So don't leave any gaps in your spraying schedule." Places where water has stood are at extra risk. "There the onion is weakened and busy making new roots. And the conditions for the fungi are ideal," concludes Van Mol. Watch the video about applying MH below: