De onion experts from Syngenta Seeds regard the longest day as an important switching moment in onion cultivation. "The pipes have been laid and the bulging will start soon. The onion must be in top condition to grow optimally in the next two months."
"Officially, it's all about the crop stage, but in practice it often coincides with the longest day," says Kees Jacobs. "The crop is now in place and the number of pipes will not change much, with perhaps an exception for the late sown fields. You can now dot the i's and cross the t's so that the onions are in top condition for the second part of the season. "
Together with colleague Michiel van Mol, Jacobs examines the most important points of attention, starting with the weeds. "If the weeds are not too bad, I would just weed a round by hand," says van Mol. "And then be especially careful with small ragworts. A hair root is enough for them to continue growing. I know growers who simply take them with them and remove them from the plot. And if you expect a lot of seed sprouts, now is the time for a final herbicide spray. Make sure you don't pester and stop the crop unnecessarily. So take a good look at what is already there and what you expect in terms of weeds. And take the weight of your soil into account."
To hoe or not
When you think of weeds, you may also think of hoeing. "The rule of thumb is that you can hoe until the onions touch each other in the row," says Jacobs. "Hoing provides more oxygen in the soil and onions usually respond positively to this. But there is also a risk of root damage and that can be an entry point for fusarium. So if you decide to hoe, do it as early as possible."
In practice, the start of the bulge is often also the time for the first fungicide spraying. "Downy mildew has already been observed in onion sets", warns van Mol, "so you know that it will also appear in the seed onions. If spores are present, one night of dew is enough for infection, but it can take another ten to twenty days after that. before you actually see the damage. With the resources we still have, intervention is no longer possible, so don't wait too long with the first preventive spraying."
Over-fertilization and thrips
The second half of June is also an excellent period for a final fertilization, according to the onion experts. "Keep in mind the state of your crop", Jacobs reminds. "If you miss 20% or more plants, the over-fertilization can be reduced by the same percentage. The fertilizer is expensive enough." Thrips control is also not cheap. "But doing nothing costs more," says van Mol. "In the past period the weather has been fertile and that is the best weapon against thrips. But you still have to be careful. At higher temperatures the cycle of the thrips goes much faster and surprises are lurking. So look a lot in your crop and spray as soon as you She sees."
sustain growth
With the precipitation of early June still fresh in their minds, not every grower will think about irrigating yet, but the first reels have already been spotted in the onions in the Southwest. "A good moisture supply is crucial to keep the crop growing," says Jacobs. "A crop that grows is more resilient. Growth also means a stronger foliage device and therefore a greater yield potential. And many crop protection products work better with growth due to the spread in the plant. So irrigating can be an important cultivation measure. And don't forget that in summer conditions you can , such as last weekend, just 20 to 30 millimeters per week evaporates, then the precipitation disappears quickly." Van Mol adds that the grower must continue to monitor the condition of the foliage. "If the foliage wears out or becomes ironed, it becomes more susceptible to fungal infections. That's a good time to stop watering."
The last point of attention is the MH spraying. Jacobs: "It will take some time before that, but anyone who has a thin or irregular position of his onions, as you unfortunately regularly see on clay plots, should seriously ask himself whether the batch can be stored and whether an MH spraying is therefore necessary. makes sense. Think about it carefully in the coming period and discuss it with your advisor."