• Alex Savin
• March 14, 2022
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Biological and Integrated Pest Control in Greenhouses

The growth of popularity of greenhouses has been great in the recent past and growing vegetables in greenhouses have become a serious business. Pests always present problems even in greenhouses and people are trying to find ways of fighting them without endangering plants. In this article, we will talk about the experience of farmers in pest control.

Pest Control Basics

Pest control refers to the regulation or management of a species defined as a pest, usually because it is perceived to be detrimental to a person’s health, the ecology, or the economy.

Anthomyiidae_spA greenhouse (also called a glasshouse) is a building in which plants are grown. These structures range in size from small sheds to very large buildings. A miniature greenhouse is known as a cold frame. Greenhouses protect crops from too much heat or cold and help to keep out pests. Light and temperature control allow greenhouses to turn in arable land into arable land, thereby improving food production in marginal environments. Because greenhouses allow certain crops to be grown throughout the year, greenhouses are increasingly important in the food supply of high latitude countries. Greenhouses are often used for growing flowers, vegetables, fruits, and tobacco plants. Bumblebees are the pollinators of choice for most greenhouse pollination, although other types of bees have been used, as well as artificial pollination. Hydroponics can be used in greenhouses as well to make the most use of the interior space.

Pest Control in Greenhouses

The controlled environment of greenhouses, the high value of the crops, and the limited number of registered fungicides offer a unique niche for the biological control of plant diseases. During the past ten years, over 80 biocontrol products have been marketed worldwide. A large percentage of these have been developed for greenhouse crops. Products to control soilborne pathogens such as Sclerotinia, Pythium, Rhizoctonia, and Fusarium include Coniothyrium minitans, species of Gliocladium, Trichoderma, Streptomyces, and Bacillus, and nonpathogenic Fusarium. Products containing Trichoderma, Ampelomyces quisqualis, Bacillus, and Ulocladium are being developed to control the primary foliar diseases, Botrytis, and powdery mildew. The development of Pseudomonas for the control of Pythium diseases in hydroponics and Pseudozyma flocculosa for the control of powdery mildew by two Canadian research programs is presented. In the future, biological control of diseases in greenhouses could predominate over chemical pesticides, in the same way, that biological control of greenhouse insects predominates in the United Kingdom. The limitations in formulation, registration, and commercialization are discussed, along with suggested future research priorities.

European Experience in Pest Control

Crop protection in European greenhouses became strongly chemically oriented shortly after the Second World War in the 1950s. But an excellent climate for the fast reproduction of pests and diseases demanded high spray frequencies and, thus, resulted in the quick development of resistance against pesticides. This initiated a search for alternatives to chemical pesticides. The first natural enemies for control of pests in European greenhouse vegetables became available in the 1960s. A change from chemical control to very advanced integrated pest management programs (IPM) took place in a time span of about 20 years. Nowadays, growers worldwide annually introduce millions of natural enemies for pest control. About 100 species of beneficial organisms are commercially available for control of all-important insect and mite pests. In the main vegetable crops in northern Europe, most if not all insect problems can now be solved without the use of insecticides. The change to IPM was not based on idealism about a cleaner or healthier environment but was rooted in clear advantages for the grower. 

The development of biological control of diseases has started recently, and the first practical successes have been obtained. Integrated management of pests and diseases without conventional chemical pesticides is a goal that will be realized for most of the important vegetables in Europe within a decade. IPM is not limited to greenhouse vegetables but is increasingly used in ornamentals. New activities in plant breeding research aim at (1) combining aspects of host-plant resistance with biological control, (2) selecting plant cultivars that are able to attract natural enemies after they have been attacked by pest organisms, and (3) selecting plant cultivars that produce a better “working environment” for biological control agents. Because of the specific advantages of biological control for the growers, greenhouse crops will be produced without the need to use conventional pesticides in the very near future. At the same time, this results in a cleaner environment, in satisfying the demand of consumers for pesticide-free food, and in sustainable crop protection.

In Europe, commercial use of biological control has seen a very fast development during the past 30 years. Currently, Europe has 26 companies that produce more than 80 species of natural enemies. The 29 most commonly sold natural enemies are discussed in this survey. The recommended release rate, the unit of sale, the target pest(s), and the number of companies producing a certain natural enemy are specified. Large differences in prices for biological control agents exist between Europe and the United States. Many more species of natural enemies are commercially available in Europe than in the United States, mainly as a result of the much larger greenhouse industry in Europe.

Farmers Arms Race

A fight against pests is a never-ending one. All farmers are hoping to destroy pests without pesticides and save the health and good quality of their plants. Biological control is the thing that is talked about and scientific research is continuing in that area.