In the pilot project "Growing Tomatoes without Sulphur," two crop protection strategies (with and without Macrolophus) are being tested in unlit tomato greenhouses. The cultivation started in week four and is closely monitored for diseases, pests, and natural enemies. This pilot highlights the crucial role of Macrolophus pygmaeus in controlling a wide range of pests. Jeannette Vriend provides an update on behalf of Glastuinbouw Nederland.
Rapid Spread of Predatory Bug
The predatory bug, Macrolophus, was introduced in week ten in the middle row of one of the greenhouse compartments at a dosage of 2.5 per m². For six weeks, Artemia cysts (500 g/ha) were distributed weekly over the entire crop with a Nutrigun to feed the predatory bugs. The supplementary feeding was deliberately spread beyond the introduction row to ensure the predator dispersed rapidly. Macrolophus established itself well, and by week 22, we observed an average of one predatory bug per leaf.
Whitefly, Spider Mites, and Aphids
At the time of Macrolophus release, only a few spider mites were present, and whiteflies were absent. Despite introducing the predatory mite Phytoseiulus persimilis and the gall midge Feltiella acarisuga, the number of spider mites increased in both greenhouses. However, Macrolophus demonstrated its effectiveness not only against whiteflies in tomato cultivation but also against spider mites and aphids. In the greenhouse with Macrolophus, only seven spider mites were found, compared to 33 in the greenhouse without Macrolophus. Furthermore, no aphids were detected in the greenhouse with Macrolophus, while 12% of the greenhouse without Macrolophus was infested with a mixture of potato aphid and Persian aphid.
Deployment of Predatory Mite
The predatory mite Pronematus ubiquitus was deployed three times (25, 25, and 50 per stem) starting from week six and was supplemented weekly or biweekly with lime pollen (Nutrimite). This predatory mite acts preventively against tomato rust mite (Aculops lycopersici) and can also reduce powdery mildew when its population levels are high. The first mildew spots were observed early in week 14, when Pronematus had not yet established sufficient numbers (less than 0.5 predatory mites per leaf). To curb disease development, both greenhouses were treated with two sprays of Fungaflash (weeks 18 and 19) and two sprays of Ortiva (weeks 21 and 22). After these treatments, the predatory mites were still present, and their effect on tomato rust mite will be tested in July.
Funding of the Pilot
The pilot is part of the "Greenhouse as Ecosystem" program. It is funded equally by the practical program "Plant Health and Foundation Knowledge in Your Greenhouse" (KIJK) and the Tomato Crop Cooperative. Additionally, there is significant in-kind support from the involved parties (Biobest, Bioline, and Pats), who provide biological control agents, monitoring, and reporting. The demonstration is being conducted at Vertify, located at Demokwekerij Zwethlaan.
Source: Glastuinbouw Nederland