Phytotoxicity of tolylfluanid in tomatoes.

The use of Euparen Multi (tolylfluanid) for controlling Botrytis cinerea in tomatoes has been decreased the last decade for several reasons. Because of the lack of different fungicides with a good efficacy it is important that growers can use different fungicides to prevent development of resistance of Botrytis cinerea against many fungicides. Tolylfluanid has negative side effects on some insect populations that are used for biological control. It is known that Euparen Multi and Euparen can have a negative effect on some predatory mites (Schmidt and Zeller, 1998) such as Phytoseiulus persimilis and some parasitic wasps like Encarsia formosa, Eretmocerus eremicus, Diglyphus isaea and Dacnusa sibirica. Recently investigation indicates that this fungicide is harmless for the predatory bug Macrolophus caliginosus (Biobest, 2006) frequently used in the cultivation of tomatoes as a predator for whitefly (Trialeurodes vaporariorum). To investigate if tolylfluanid has a phytotoxic effect on tomato plants an experiment was performed. Young tomato plants were used, who are more sensitive. These plants were subdivided in different groups, from which each one was sprayed with a different concentration of tolylfluanid. The highest concentrations of tolylfluanid were used to stimulate the visibility of the possible phytotoxic effects. Results of this experiment demonstrate that there wasn't a difference between the different groups that were sprayed with tolylfluanid or the control group. This indicates that tolylfluanid doesn't seem to be phytotoxic. It is also important to mention that this experiment was done in the fall when the intensity of the sunlight was decreasing. There still exists the possibility that extreme irradiation in combination with tolylfluanid can provoke a phototoxic effect on young tomato plants.