Preventing Yield Loss from Flea Beetles

Flea beetles are a common crop pest of crucifers in Ontario and overwinter as adults near the soil surface in debris and stubble from the previous crop. They typically become active with the first extended period of warm weather in the early spring as the leaf litter begins to thaw. The beetles feed on weeds throughout the field and have the ability to fly on calm days and will attack brassica seedlings as they emerge or transplants as they are planted.

Females will begin laying eggs in soil for about 30 days. Flea beetle larvae will hatch from eggs 12 days later and feed on the root hairs and taproots of seedlings. Left unchecked, adults will feed on leaves of transplants and the larvae will burrowing into the plant near the juncture of the root and stem. Randomly inspect 25 plants and record the number of beetles on each plant and divide by 25 to get an ‘average’ number of beetles per plant. The threshold for treatment is 1 flea beetle per plant up to the 6-leaf stage. After this stage, feeding will not interfere with plant growth however damage at later stages may have an impact on marketability and quality. Optimum flea beetle management is a combination of insecticide timing and insecticide selection.

Figure 1. Flea Beetle damage on broccoli.
Figure 1. Flea Beetle damage on broccoli.

To prevent the development of resistance, it is essential to always rotate between different insecticide groups and/or tank mix with a broad spectrum insecticide. Current products registered for flea beetle management are listed by insecticide group below.

Group 1A
Carbaryl

Sevin XLR
Rate PHI Notes
1.25–2.5 L/ha
(0.5–1 L/acre)
5 Kohlrabi. See label for restricted entry intervals.
21 Chinese cabbage and mustard greens. See label for restricted entry intervals.

Group 3A
cypermethrin

Mako
Rate PHI Notes
87.5–125 mL/ha
(35–51 mL/acre)
3 Broccoli, Brussels sprouts, cabbage and cauliflower. Do not apply to muck soils.

deltamethrin

Decis 5 EC
Rate PHI Notes
150–200 mL/ha
(61–81 mL/acre
3 Cabbage only. Do not apply after August 1. See label for precautions on high organic content soils.

lambda-cyhalothrin

Matador 120EC, Silencer 120 EC
Rate PHI Notes
42 mL/ha
(17 mL/acre)
1 Cabbage. 24-hr restricted entry interval.
3 Broccoli, Brussels sprouts and cauliflower. 24-hr restricted entry interval.

permethrin

Ambush 500EC
Rate PHI Notes
70–140 mL/ha
(28–57 mL/acre)
3 Brussels sprouts, cabbage and cauliflower. See label for guidance on adjuvant use. Re-entry permitted once spray deposit has dried.
7 Broccoli. See label for guidance on adjuvant use. Re-entry permitted once spray deposit has dried.
Perm-UP
Rate PHI Notes
90–180 mL/ha
(36–73 mL/acre)
3 Brussels sprouts, cabbage and cauliflower. See label for guidance on adjuvant use. 12-hr restricted entry interval.
7 Broccoli. See label for guidance on adjuvant use. 12-hr restricted entry interval.
Pounce 384EC
Rate PHI Notes
90–180 mL/ha
(36–73 mL/acre)
3 Brussels sprouts, cabbage and cauliflower. See label for guidance on adjuvant use. Re-entry permitted once spray deposit has dried.
7 Broccoli. See label for guidance on adjuvant use. Re-entry permitted once spray deposit has dried.

Group 4A/3A
imidacloprid/deltamethrin

Concept
Rate PHI Notes
650 mL/ha
(263 mL/acre)
7 See label for complete list of brassica crops, including specialty brassicas. Do not apply foliar group 4 insecticides in the same season as a seed treatment, soil, in-furrow or transplant application. See label for rotational crop restrictions. 12-hr restricted entry interval.

Group 5
spinosyn

Entrust
Rate PHI Notes
364 mL/ha
(147 mL/acre)
3 See label for complete list of brassica crops, including specialty brassicas. Suppression. See label for restricted entry intervals.

Group 28
cyantraniliprole

Exirel
Rate PHI Notes
500-1000 mL/ha
(202-405 mL/acre)
1 See label for complete list of brassica crops, including specialty brassicas. See label for guidance on adjuvant use. Do not make a foliar application for a minimum of 60 days following a soil application of any group 28 insecticide. See label for tank-mix, crop tolerance information and rotational crop restrictions. 12-hr restricted entry interval.

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