Novel approaches to integrated pest and disease control in glasshouse vegetables in the Netherlands

Abstract

As a result of government policy and consumers' attitudes to environmentally compatible growing systems, research is focused on reduction of pesticide input into the environment. This aim is approached in different ways. With so‐called “closed growing systems”, soil fumigants are no longer needed, resulting in an estimated 60% reduction in the total use of pesticides. Further, far smaller quantities of (systemic) pesticides need to be added to plants, via the nutrient solution, than with soil‐grown crops. Water disinfestation is essential to minimize the spread of diseases and heat treatment and ozonization are already used under commercial conditions. Filtration appears to be neither reliable nor practical. Other disinfestation methods are under investigation. Ventilators may be provided with insect‐proof screens to minimize infection pressure, especially on young plant material. Air filters in combination with mechanical ventilation may be an option for the future to raise healthy plants. A further reduction in the use of pesticides can be achieved by developing biological and integrated control of insects and fungi. Simultaneous application of several biocontrol methods in the fruit vegetable area has increased the complexity of IPM. Open rearing systems of parasitoids on alternative hosts to control cotton aphids and leaf miners are promising. IPM is highly dependent on the availability of selective chemicals. Biological control of root‐infecting fungi in substrate crops shows promise. Integrated control of powdery mildew in cucumbers using a combination of nutritional and climatic management and varieties showing partial resistance will be studied. Improvement of application techniques for pesticides is being studied by plant pathologists in cooperation with technical experts. The aim is to reduce pesticide application rates, to minimize losses to the environment and to avoid health risks for the worker. By developing decision‐support systems for crop protection, optimal use of beneficial insects is achieved and unnecessary applications of chemicals are avoided. A programme to develop such a system for the sweet pepper crop is under way.

Climate change, agricultural insecticide exposure, and risk for freshwater communities

“…The Netherlands were omitted from the statistical analyses because, in this country, a substantial proportion of the total value of agricultural production is realized in greenhouses (∼20% [van Lenteren 2000]). This method of cultivation requires particularly high rates of pesticide application and therefore might bias the relationship between temperature and application rate (Vansteekelenburg 1992). We tested several climate descriptors (mean annual temperature for each country, sums of precipitation or average temperatures over different periods, the number of months in which certain thresholds were exceeded, or combinations of all of these), which were weighted by the proportion of arable area in each cell, and used log 10 ‐transformed rates of current insecticide application.…”