The sustainable treatment method CATT has been used successfully for years to deal with quarantine insects on strawberry plants. However, CATT is not only useful to strawberry plant breeders; it is also effective in combatting pests in other plant products.
CATT (Controlled Atmosphere Temperature Treatment) was developed by two groups within Wageningen UR: Food & Biobased Research and the Applied Plant Research (PPO). The method involves placing plants in a gastight room for a specific period and treating them with a combination of raised temperatures and certain atmospheric conditions, such as oxygen and carbon dioxide concentrations. Humidity, packaging and other limiting factors may also be applied in the method. CATT is not only suitable for keeping plant material free of infestation; it is also useful as a quarantine treatment when importing or exporting.
Alternative for methyl bromide
According to Jan Verschoor, a researcher at Food & Biobased Research, breeders use CATT mainly as an alternative for methyl bromide. "This is an effective disinfectant but is now forbidden in Europe. CATT is a sustainable, non-chemical alternative. Strawberry growers have been using CATT for years to destroy the extremely damaging strawberry mite.”
Since the end of 2012 an amended form of the method has been used with success against two other undesirable guests: the root lesion nematode Pratylenchus penetrans and the northern root nodule nematode Meloidogyne hapla. If these are discovered during a check, the whole batch has to be destroyed. Verschoor: “CATT allows you to control the strawberry mite and the destructive nematodes in one go. That is why the method is of such value to plant breeders.”
At Wageningen UR, tests have been carried out on other insects and plants too. The results are promising. “We now have a useful list of pest-plant combinations for which CATT works well. For example, the western flower thrips and whitefly, two undesirable invaders in greenhouses. And we can control the tomato leaf miner effectively. We are also doing research into insects such as the fruit moth, the tulip mite, the Asian tiger mosquito and into the chitwoodi (rootknot nematode), a quarantine nematode you may come across in seed potatoes.”
Verschoor and his colleagues are usually quite good at predicting whether a method will work or not. "But if you’re planning to apply CATT in practice, thorough research is necessary. For example, you need to make cultures of every insect stage because certain stages are usually less susceptible to the treatment. However, you also need to look into how a CATT treatment affects the various varieties, sources and qualities of plant material. So, after treatment, we have to grow the plants on or determine the shelf life of the fruits.”
In other words, it is not that easy to find exactly the right CATT formula. "Each plant species requires specific conditions to survive. At Food & Biobased Research, we know a lot about the quality of fresh products from the moment of harvest right up to consumption. We also know how to put technology on the market. For a thorough knowledge of insects and nematodes, we work together with entomologists and nematologists from other institutes within Wageningen UR. This combination ensures we can rapidly develop the right solutions.”
Sticking our neck out
Verschoor is predicting a golden future for CATT. “Companies who still use chemical agents are at risk. Those agents could be taken off the market, with negative effects on operational reliability. CATT is a sustainable method, with no legislative restrictions. For new chemical pesticides, an expensive and long-drawn-out admission procedure is necessary. But not for CATT.”
Nevertheless, companies who want to succeed do have to stick their necks out because practical research is essential for development of a robust CATT-treatment. Organizing the intellectual property properly is also important. Experiences with CATT application against strawberry mites show that this can be realized by charging lower treatment fees for companies that invested in the development of CATT Verschoor says.