From a year with severe infestation with the tomato bronchitis virus and high thrips pressure to a cultivation season in which thrips prevention is well under control and no virus has occured. That is, in one sentence, the summary of the result of a new strategy in the biological crop protection, hygiene and disinfection at nursery Het Westland in Naaldwijk, the Netherlands. 

At the end of 2019, under the guidance of Royal Brinkman the strategy changed. For several years they had been struggling with thrips problems, resulting in the spread of the tomato bronchitis virus in one of the greenhouse section of the 2.7 hectares. The virus can be recognized by vein attack and chlorosis on leaves, stems and fruit. Entire plants fail and harvest losses are considerable. The tomato bronchitis virus is transmitted by adult thrips, but infections can occur very early in the year and it is then unlikely that thrips are already flying around outside the greenhouse. These thrips have survived the crop rotation.

​​​​- Thimo van Marrewijk, pepper grower at nursery Het Westland​​​

The risk of problems can be limited by taking the measures during the crop rotation and using biological thrip control. Chris Bos, responsible for the cultivation location Vlietweg at nursery Het Westland: "Last cultivation season we had serious tomato bronchitis virus infestation in one greenhouse section of 2.7 hectares of the total of 4.2 hectares sweet peppers. Recommended by Royal Brinkman, during the crop rotation at the end of 2019, we started cleaning the gutters and the ground cover with the foam disinfection Menno te Forte. This has killed the green attack and apparently also had an effect on thripwings. Under the guidance of crop protection specialist Martijn Maat of Royal Brinkman we started the new strategy to control the thrip." The biological control with montdorensis has been applied at nursery Het Westland from the beginning. Instead of one montdorensis bag for every 6th plant, a strategy with a montdorensis dose for every plant has been applied. Martijn Maat: "We choose for a pot introduction; in each rockwool pot, a mix of montdorensis and Power Food was introduced from week 4 with the application of a spoon (5 ml). Substrate proved to be the ideal habitat for the further development of predatory mites and feeding mites, the population structure went well and we immediately found predatory mites on every stem. Until May 2020, we saw no thrips." Chris Bos adds: "It went very well. Of course this method is more labour-intensive, because of the spreading per individual plant, but this strategy succeeded and we benefited a lot from it.” 

The Orius predatory bug is known as trusted controller of adult thrips in sweet pepper cultivation. However, in recent years, nursery Het Westland was not satisfied with the population structure and the control effect of this Orius. Royal Brinkman suggested testing Orius in combination with the new Power Food Plus in a late planting of sweet peppers from week 12 at the location Vlietweg in Naaldwijk. The supplier Agrobío has worked hard to formulate a powerful supplementary diet for Orius; several ingredients have been mixed in the new Power Food Plus. The first predatory bugs were introduced in March and the trial was set up in week 12 and 13 with Orius and Power Food Plus and with Artemenia at nursery Het Westland. Chris Bos: "We applied the Orius in sweet pepper halfway through the crop on the pepper leaf, and the Power Food Plus and Artemia over the head. Martijn Maat of Royal Brinkman did the counting."

During the trial, the results showed that the number of nymphs was the highest in which the combination of Orius and Power Food Plus was applied. Martijn Maat: "The trial has shown that we realised an acceleration by a factor of 3 offering a supplementary feed to the Orius predatory bug. That is a good acceleration of the structure of the total population. Power Food Plus is a strong supplementation product that supports Orius to quickly reach strength in the crop. It was also noticeable that the montdorensis with Power Food Plus had developed much stronger and had therefore also benefited from this extra food.”

​​​​- Martijn Maat, Royal Brinkman​​​

The results of the new strategy for thrips control at nursery Het Westland were excellent last cultivation season. No problems with thrips also meant no burden of the tomato bronchitis virus. Chris Bot: "Not only the thrip control went well, in all areas the biological control went well, including white fly, red spider mite and aphids.”

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