Integrated pest management can result in savings

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By Elmer Kaskiw

Farm Production Advisor, MAFRD

Many of us are likely familiar with the term Integrated Pest Management but not many of us have likely actively implemented a planned IPM program. A planned IPM program recognizes that your crop and varietal selection is an important consideration when planning your fertility program, which is a significant part of your weed control program, which in turn impacts your disease and insect control program. These decisions are all part of a large ecosystem with lots of interactions that need to be considered or managed collectively. 

IPM is important on several fronts. Public image is one of them, as producers must demonstrate that they are actively trying to minimize pesticide use wherever possible. This does not mean that IPM means no pesticide use but instead, the strategic use of pesticides as a tool in managing pest outbreaks when necessary. Sometimes, our management decisions can create our own problems, especially when we have limited choices in regards to cropping options.  

Over the better part of the last two decades much of the Parkland region has been stuck financially and agronomically in a wheat, canola, wheat rotation. This has led to new and more virulent strains of disease and an ever increasing list of herbicide resistant weeds. Crop diversity will need to become an important IPM component in the future if we hope to overcome these production issues.

Insect control is likely where we see the greatest potential for IPM control measures. Many damaging insects have natural predators that help keep populations at manageable or below threshold levels. The use of an insecticide at below threshold levels will in many cases not only kill the targeted insect but will also take out the beneficial predator resulting in an insect pest populations at just below threshold levels. 

This is the typical result when an insecticide is used for the control of wheat midge. The insecticide kills both the wheat midge and its natural predator resulting in an ongoing spray program to keep populations just below thresholds. The best control of wheat midge populations is to use culture control by planning to seed wheat early, allowing the crop to flower prior to peak wheat midge numbers and preventing the midge from laying their eggs and affecting wheat heads. 

The same holds true with bertha armyworms affecting canola.  Every time there is an outbreak in bertha armyworm, there is an increase in beneficial insects and an increase in a disease that affects them. If we spray these fields when we don’t have to, then we artificially keep the bertha armyworm levels down at around threshold levels and we don’t get a build up of the beneficial insects or disease which results in a cycle of always having to spray. 

Another example of disease as a beneficial control occurs in grasshoppers. A fungal disease can kill grasshoppers, and nature has given the fungal disease a helping hand with something in the fungal reaction that makes the grasshopper climb to the top of the plant to die. This helps to disperse the spores to spread to other grasshoppers. 

There are time however when the beneficial insects are overwhelmed by the insect pest and can cause significant crop damage. This is when the sprayer and thresholds becomes part of the IPM solution. Thresholds are tied to a point in time of the lifecycle of the insect and the stage of the crop. Twenty bertha armyworm larvae per square metre have to happen when the canola has pods. If you have 100 larvae on the leaves and no pods then they won’t do any damage. The other consideration regarding thresholds is that you can’t scout fields from your truck or base your decision on what your neighbour is doing. Every year spray decisions are made because of the neighbours’ and every year some fields are sprayed that didn’t need to be. Fields need boots on the ground for accurate threshold calculations and then a determination if the judicial use of an insecticide if warranted. 

In a year of tight grain and oilseed margins, there are substantial dollars to be saved by implementing an IPM program for your farm. The key is to make it an integral component of all your crop planning and pest management decisions from seeding to harvest.