[The Effect of Fungus Diseases On Integrated Pest-control in Glasshouses]

In glasshouse crops, more and more natural enemies are being introduced to control the development of the major pests. A new biological control strategy in tomato crop is studied in our center which consists of using only predators and parasitoids instead of insecticides and acaricides. But it could be that this reduction of pesticides - only fungicides are still necessary - has some impact on aerial fungi development and thus makes it necessary to increase the number of treatments against these. To test this assumption we have grown tomatoes in glasshouses that were divided into two identical parts so that a classical control by use of acaricides and insecticides is applied in one part and a biological control, only by release of natural auxiliaries in the other. The development in the crop of powdery mildew (Leveillula taurica) and grey mould (Botrytis cinerea) was determined in the two cases in view of the fact that an equal number of treatments against these fungi was applied on both sides. As a result we observe a more extent development of these fungi in the crop where biological pest control is applied. It would appear that insecticides and acaricides have an effect on these fungi and their application would reduce these fungal diseases problems in a crop. In conclusion, it seems necessary to find alternative methods of fungal control; if not, the benefits of fewer pesticides use will be lost.