After a mild winter and a warm May, there is now a real chance of finding thrips in seed onions. Michiel van Mol and Kees Jacobs emphasize the importance of an early approach to this small but very harmful insect. "You only win the battle at the beginning of the season."
"Don't be misled by the position of the crop. Thrips don't look at that either!" onion experts Kees Jacobs and Michiel van Mol cannot emphasize it enough. "Starting early in tackling thrips is crucial. You have to make sure that the numbers of thrips remain low at the start of the season. If you don't do that, you won't win the battle later in the season. The power of combat is really in an early start. And those thrips will definitely come in early June."
Inspect regularly
According to Jacobs and van Mol, the circumstances give sufficient reason to inspect the seed onion crop regularly and accurately from the beginning of June. "We had a mild winter and so many thrips will have survived in the bushes. They become active quickly," says Jacobs. "And the warm month of May ensures that the pupae in the ground can continue their development quickly. Before you know it, thrips larvae can be found. And the earlier the cycle starts, the more trouble you can get later in the season. expect if you don't intervene in time." The onion experts at Syngenta Seeds also point out that thrips have already been found in onion sets. "And onion sets are no longer alone in the Southwest."
Incidentally, the conditions for the onion plants are also favourable, says Van Mol. "Now that the rain has fallen, the onions are well on their way to growth. The relatively high temperatures of the past period also help. A well-growing crop without stress is the best remedy against damage caused by thrips. But that does not affect the fact that you can and aim for zero tolerance for this insect by mid-July."
Selective resources
According to Jacobs and van Mol, there is little room for discussion about tackling thrips. "Spray in time with selective systemic agents. They are strong on thrips and spare the natural enemies, such as rove beetles." According to the onion cultivation experts, the fact that these products need a week to 10 days before the entire onion plant is protected is an extra reason to spray on time. "Seeing thrips means spraying", says van Mol. According to him, a reduced dosage is only an option for very small crops. "But then you also have to come back earlier and in practice people sometimes forget that."
sustain growth
In the coming month, according to the Syngenta onion experts, the growers must do everything they can to maintain the growth of the onions. "Not only to keep the crop resistant to thrips, but also to form a good leaf apparatus. Because that happens in June and is the basis for a good yield. If the soil becomes dry again, start irrigating on time. And make sure the fertilization status is in order."
The focus on thrips should certainly not wane until July, conclude Jacobs and Van Mol. "And be extra alert if alfalfa, grass seed or flax is grown near your onions. When harvesting those crops, large flights of thrips can sometimes be released."