Residue-free tomatoes - a proven approach

In response to steadily growing consumer demand for residue free tomatoes, growers are rising to the challenge − according to Biobest, a leader in natural crop care systems. Based on good results in France and Benelux countries, other markets are now showing great interest in this technology.

"Intensive scouting and monitoring programmes are the bedrock of residue free production," says Sam Gui, crop management specialist at Biobest. "Our approach relies on knowing when pests first appear in the crop and in taking immediate reaction with the right biological strategy. Delay the start, or employ the wrong strategy, and spraying may become inevitable with everything that this entails. Another prerequisite is good pre-crop hygiene."

Residue free glasshouse whitefly control relies on a preventative approach. "Employing Bug-Scan yellow sticky traps to monitor the emergence of the first whitefly enables growers to make prompt introductions of our Encarsia-System," explains Sam Gui. "The parasitic wasp Encarsia formosa can establish and start to build up in a crop when pest levels are very low. As the season progresses the parasite is in a strong position to keep on top of the rising pest population.

"Our Macrolophus-System, employing the generalist predator Macrolophus pygmaeus, also plays a key role in the strategy. There is the option to use it in combination with our Nutrimac extra protein-rich food source to accelerate establishment. By starting early and having a stable population in place, growers are achieving season long whitefly control without spraying. Should the pest population exceed the damage threshold, residue free botanical pesticides can be used correctively."

Phytoseiulus persimilis remains the backbone of integrated pest control strategies for spider mite. A curative control, careful scouting is a must as this predator cannot survive in the absence of the pest.

"Our Macrolophus-N-System can also play a vital role," says Sam Gui. "Containing various nymph stages, when released into spider mite hotspots these predators start feeding straight away."

As resistance builds to bifenazate containing miticides, growers employing conventional chemical control programmes are increasingly turning to these tried and tested biocontrol solutions.

Aphid control can prove particularly challenging in residue-free crops. According to Sam Gui success again hinges on taking a preventative approach, employing careful scouting and early predator establishment ahead of the pest. "Our strategy in tomato crops centers on Aphidoletes aphidimyza," he explains. "The pupae of this predatory gnat are unable to hatch in dry areas. We therefore recommend growers inoculate into specially designed release buckets providing the required moist medium." 

When the first aphid hotspots are detected, Biobest recommends introducing supplementary parasitoids such as Aphidius colemani (Colemani-System) and Aphidius ervi (Ervi-System).

Sam summarises: "A suite of tailor-made biological strategies for each of the main tomato pests, that’s what helps our growers succeed in residue-free tomato production."