Arne van Aalst is soon to take up his position at Koppert Biological Systems. Van Aalst, who is now general director at the growers' association...
Swirskii as a beneficial to combat thrips
26 June 2010
The Dutch rose grower Paul de Groot – owner of a four-hectare large business, Flevoland Flowers – has absolutely no problems with whitefly or mealy bugs. But he does have a huge problem with thrips. He’s doing everything he can to keep the thrips under control. Consistently using Amblyseius swirskii should help him do just that.
For several years, Paul de Groot has been plagued by thrips in every season. They most likely fly in from arable crops in the surrounding area (or else they are present but dormant at the start of a new crop cycle), and they are resistant to most chemical agents.
Swirski-Mite (Amblyseius swirskii) enables him to attack the larvae. The rose grower does not want to use chemical agents, which he considers detrimental to growth, quality, and production. “I also came up against issues in terms of crop protection. Most chemical agents aren’t effective anymore against thrips. The agents which were available also killed all the natural enemies of spider mite. That doesn’t help at all.”
For this reason, he switched to Swirski-Mite last year to combat thrips. Research carried out by Wageningen University Greenhouse Horticulture indicates that swirskii is easier to control than cucumeris and as a result is more effective, and it also attacks spider mites.
Like a boomerang
Koppert is carrying out extensive tests on a large number of Dutch rose-growing companies, with the help of bi-weekly sticky trap counts, in order to develop an effective method of combating thrips. In 2009, at Paul de Groot’s company, much better results were achieved by using integrated methods than had been achieved with chemical agents in 2009. The grower distributed fifty Swirski-Mites per square metre over the entire crop every two weeks, and in highly infested areas he released as many as 100 to 300 per square metre. Conserve (Spinosad) or Match (Lufenuron) were used to extinguish thrips hot-spots as needed.
This year, he will be releasing fifty mites per square metre every week, in the hopes of reducing the population even further. The standard procedure seems to be working rather well. In that part of the greenhouse where Koppert has been taking long-term measurements, good results on thrips have been achieved.
In another part of the greenhouse, there have been some problems with thrips this year. According to Paul, this is the result of misplaced frugality. “The areas where we are now having problems are the areas where last year we temporarily tried decreasing the dosage to twenty-five swirskii mites per metre every two weeks. That didn’t turn out well. That frugality is now hitting us in the face like a boomerang. The solution for this year is very simple: fifty beneficials per square metre per week, fifty-two weeks a year, even after we’ve sprayed for other insect pests.”
Putting all the chips on swirskii
Paul de Groot has complete faith in Amblyseius swirskii. He achieved good results last year, and besides, he doesn’t see any attractive alternatives. “We’ll continue to put all our chips on swirskii, and we’ll apply it over the entire crop. In addition, we’ll keep scouting for them and we’ll hang up a lot of sticky traps.”
For more information visit: www.allaboutswirkii.com