Flea beetle damage is most severe the first two weeks
after canola seedling emergence.
At the three- or four-leaf stage,
the plants are generally established and can outgrow the feeding damage.
Seed treatments provide protection
for 3-4 weeks from time of planting, so in some cases control may have run out
before canola is past the critical 3 to 4- leaf stage.
Flea beetles can damage plants
very quickly in warm, sunny weather.
The economic threshold for flea
beetle feeding on canola is when there is 25% damage. (see attached photo).
25% flea beetle
damage
If heavy flea beetle damage nears
threshold levels and high numbers of flea beetles are noticed in the field,
apply foliar sprays as soon as possible, since flea beetles can cause
substantial damage quickly.
Before spraying for weeds, check
fields for flea beetle activity, so flea beetle control can be applied at the
same time.
When scouting fields for flea
beetle damage, it is important to understand that flea beetles generally invade
canola fields from the field edges. Flea beetle damage and the number of flea
beetles may be higher at the field edge than farther into the field. If this
appears to be the situation, a foliar spray around the field edge may provide
sufficient protection.
Apply sprays when it is sunny and warm, and the beetles are active and exposed on plants and soil.
Please let us know about the flea beetle activity you have found in your fields.
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