Dealing with insect pests of seedlings

A termite walks into a bar and asks, “Where is the bar tender?”

This joke right here is a witty reminder that insects love tender plant parts. Seedlings fit the profile perfectly. They are tender, succulent, close to the ground and are easy pickings for a host of insect pests. If left unchecked, these insects have no problem turning our farm into their stomping ground as they feast on our precious crops while singing their version of Weevil Weevil Rock You!

Insects can cause two major kinds of damage to growing crops. First, there is direct injury when insects eat leaves or burrow into stems. Then, there is indirect damage when an insect transmits a disease-causing organism into a crop. Early damage to seedlings produces uneven plant stands, and eventual yield loss. However, the presence of insects in a crop does not mean that there will be significant crop loss. The density of the insects has to reach a threshold that causes major concern. An economic threshold is the insect’s population level or extent of crop damage at which the value of the crop destroyed exceeds the cost of controlling the insect. In other words, if controlling the insect will cost you more money than the damage they’d cause, you should…choose the lesser of two weevils. In canola, for example, treatment is recommended when there is 25% defoliation in the presence of flea beetles.

Keeping insect infestations below significant levels is the goal. Effective control starts with effective monitoring. Every field should be monitored on a regular basis to estimate the populations of specific insect pests. A good understanding of an insect’s behaviour will help to know how best to scout for it. For example, cutworms, can be found first on hilltops because they prefer drier and warmer soils. They will eventually move to low-lying areas when their population increases.

If insect populations exceed economic thresholds, then it’s a good idea to control them using the appropriate methods. Biological control involves the use of the insect’s natural enemies. The northern field cricket (Gryllus pennsylvanicus), for example, is known to prey on flea beetles. In some cases, cultural control of insect pests using good agronomic practices such as effective weed control and crop rotation will help to manage certain insect pests. Chemical control using a good seed treatment or a post-emergent foliar application will also be effective.  So, take the sting out of problems with insect pests and talk to your SynergyAg rep about scouting and suitable solutions.

-Ikenna Mbakwe, PhD, PAg
Head of Research


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