| | Pest management is recognizing and reducing insect, disease, weed, and animal problems to an economically acceptable level. Pest management in a nursery, as in any crop situation, is an important component in obtaining a quality marketable product. Cultural, biological, and chemical controls should all be used in pest management. Pesticides must be used carefully in accordance with label instructions. An Integrated Pest Management (IPM) program promotes a responsible use of pesticides in combination with nonchemical controls and results in economical, long-term results.
Identification
In order to put any control program into practice, it is most important to properly identify the pest or pests targeted. Control options cannot be determined without this knowledge. Several texts on insect, disease, and weed identification are available and some have been referenced in this document (Appendix A).
Monitoring
Regular monitoring of the crop to determine pest populations will determine what pests are present and at what population levels as well as the population levels of the beneficial organisms. Monitoring the nursery may consist of setting out traps or checking 'hot spots', or areas more prone to the pest, and performing counts or assessing damage. Weather monitoring may be important for pests which thrive under certain climatic conditions. Monitoring is necessary to determine a control decision as well as to evaluate how effective the controls are.
Thresholds
Control guidelines, or thresholds, will determine when control methods need to be applied to prevent economic losses. The threshold is the amount of damage that will reduce the value of the crop beyond the cost of the control method used. Consider using cultural and biological control methods first, then if these are inadequate, pesticides are can be used. The most economical and reliable way to deal with pest problems is to avoid them when possible.
Cultural control
Cultural control can prevent or reduce pest problems. Cover crops between rows and mulching within rows can reduce weed problems. Choosing to grow trees which are not susceptible to a prevalent pest may avoid a problem. Pruning can remove infections of some tree diseases or remove overwintering insects. Sanitation, or removing fallen leaves and branches, can reduce overwintering insects and disease sources. Fencing the perimeter of the nursery may be the only feasible control for deer. Maintaining healthy plants will reduce the likelihood of infection.
Biological control
Biological control can also reduce pest problems. Encouraging beneficials, or the pests natural enemies, by providing environments for them to overwinter will assist in control. Predatory insects may be released and should become part of the nursery monitoring program to determine if they persist. Predatory organisms available in pesticide form, such as Bacillus thuringiensis (Bt), are usually very selective and will not harm beneficials. Timing and environmental conditions are extremely important considerations when applying biological controls.
Chemical control
When cultural and biological control methods are impractical or ineffective, chemical pesticides are usually used. Repeated use of a pesticide can result in chemical resistance in the pest. Resistance can also occur when pesticides are used at lower than recommended rates or on a continuous basis. To reduce resistance, pesticides should only be used when needed and at recommended rates. Pesticides can be alternated by using ones with different modes of action and to be effective all pesticides should be applied at the appropriate time when the pest is most vulnerable. Detailed pesticide recommendations for chemical pest control can be obtained in the Nursery Production Guides from British Columbia and Ontario and the Alberta Agriculture and Forestry publication, Crop Protection with Chemicals (Appendix A).
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