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Flea Beetles: A Common Enemy of Canola

If you are a grower of canola, you’ve most likely come across a flea beetle. Flea beetles are one of the most common pests of canola. In order to grow a successful crop, it is important to have a basic understanding of flea beetles and the management strategies needed to control these pests.

Flea Beetle Damage

Flea beetle damage from feeding may affect crop development depending on feeding intensity, crop stage, and part of the plant that has been damaged. Adult flea beetles may feed on the cotyledons, leaves, stems, and seed pods of canola, mustard and rapeseed. During the larval stages, flea beetles may feed on roots. Heavy populations of flea beetles have potential to cause extensive damage and delay maturity, causing a reduction in yield and seed quality. Yield losses around ten percent are common in areas with infestations.

Economic Threshold

The economic threshold in canola is when average leaf damage reaches 25%, if flea beetles are still present and feeding. At this point, a foliar applied insecticide is recommended. If beetles are present, it’s important to scout your newly emerging canola plants for damage daily as feeding can advance from 25% to 50% damage in less than a single day, especially in warm and calm weather conditions.

Source: Canola Council of Canada

Identification & Life Cycle

There are three known species that attack canola in Western Canada. These species include crucifer, striped, and hop flea beetles. Of these, the crucifer flea beetle is the most destructive and widespread. Adult flea beetles appear twice in one growing season.

Flea beetles have a single generation per year, overwintering as adults within debris. These overwintering adults begin feeding on canola seedlings when they emerge in spring. Offspring appear in the fall and feed on leaves, stems and seed pods.


Scouting

Scouting in early spring (May to June) is imperative to catching a flea beetle infestation as overwintering adults emerge to feed. Monitor entire fields, more frequently in warm/dry conditions. Examine cotyledons and leaves of 10 plants in five different locations within a field. Inspect for small, round holes (shot holes) in cotyledons and seedling leaves.


Preventative Measures

A few simple, good management practices can go a long way in the spring to help prevent, or at the very least reduce flea beetle damage to the crop. A good crop rotation helps promote a good, healthy crop establishment. With a good stand established there will be more plants to spread the impact of flea beetle feeding. Seeding depth is another fairly simple way to give your canola crop the best chance for success. Take the time and set your drill for optimal depth. Fast, even emergence gives the tiny canola plants the best chance to compensate for flea beetle feeding and grow through the most susceptible early cotyledon stages. Finally, canola seed treatments have been a proven method to help reduce flea beetle damage. Standard treatments such as Prosper Evergol and Helix Vibrance will provide some protection against flea beetles. For extended protection there are other treatment options including Fortenza Advanced and the very well-known Lumiderm.

It’s important to monitor your plants in the early spring as flea beetles can do a lot of damage to the emerging crop. Feeding can happen on cotyledons, leaves, stems, and seed pods of canola. Preventive measures can be taken to reduce flea beetle damage including crop rotation, seeding depth, and the careful consideration of canola seed treatments. For further information please contact the SynergyAG rep in your area!

Flea Beetles – Chewing Their Way Into June

As many people find themselves finishing up the seeding season, we also find ourselves at the beginning stages of the bug season. If you have been out and about in your fields you have probably noticed small black bugs that are the size of a pin head bouncing around. 

The striped and crucifer flea beetles are the two common species that feed on canola in the Canadian prairies. Hop flea beetles can also be found, but occur in low numbers throughout the prairies. All three species can vary in the way they look, how they feed, and when they emerge. 

When To Look For Them

Flea beetles emerge in early Spring, and can cause damage to your canola crop from emergence, up until the 3-4 leaf stage. They aren’t picky eaters, and are known to feed on the cotyledons, leaves, stems, roots or any fleshy tissue on the plant. Sunny, warm and dry weather is preferred by the beetles, but less ideal conditions don’t seem to slow them down either. They are known to increase below ground and underside of leaf feeding during the less than ideal conditions.

How To Manage Them

It is important to assess where the bugs are feeding and how much of it there is. Action threshold levels are when average leaf area loss is more than 25%, and it is considered economically beneficial to spray insecticide when the leaf area loss is above 50%. There are no established threshold levels for stem feeding, which is why it is so important to assess where the feeding is taking place. If the flea beetles are actively feeding on leaf tissue, stem tissue and/or the growing point, the action level might be lower. 

There are different control options and management practices to help mitigate the damage these guys can have on your canola crop. Seed treatment options like Prosper Evergol and Helix Vibrance are standard on your canola seed to protect against flea beetles, but you can enhance your protection by adding Lumiderm on your seed when you order it. There are also in-crop insecticide control options to cover you off if populations rise and leaf damage is above threshold levels. Lastly, there are cultural control methods such as seeding early to get crop establishment before the emergence of the flea beetles, allowing a higher tolerance to injury. The second practice is increasing your seeding rate, this can help you reduce the impact of the flea beetle damage by spreading it out over more plants allowing for easier recovery from the stress event. 

Don’t Fear Though

The sight of these pesky little bugs probably have you wondering a few different things. Such as, why your seed treatment isn’t working. The truth is, it is working. But, with the newer chemistries, the flea beetles have to feed on the plant to ingest the insecticide for it to work. Whereas older seed treatments were used as more of a deterrent or repellent. Also, seed treatments only give a 28-35 day protection window after the crop is seeded, in cooler, dry weather the crop could be slower growing and not past the 3-4 leaf stage so it is at risk for flea beetle damage. 

Contact our SynergyAG Agronomists and they can help you determine which is the right course of action against your flea beetles! 

 

Niki Beingessner CCA, PAg

Sales Agronomist – Yorkton