Be watchful for flea beetle feeding
Striped flea beetles (Phyllotreta striolata) have been emerging and feeding on volunteer canola since late March, provincial entomologist John Gavloski says in the first insect and disease report of the season issued April 27.
“We often see striped flea beetles emerge earlier than the crucifer flea beetle (Phyllotreta cruciferae) which can be the more damaging species of flea beetle in Manitoba,” Gavloski says.
Canola seed treatments generally last three to four weeks. When canola is seeded under conditions that result in quick germination and early growth the seed treatments can protect the plants from flea beetle feeding until the plants have several true leaves, after which they can compensate well for flea beetle feeding. Seeding under conditions that may result in slow emergence and slow early growth could mean that the seed treatment wears out while the seedlings are still vulnerable to flea beetle feeding. So the level of flea beetle feeding may be something to pay attention to if early-seeded canola takes a long time to get established.
Diamondback moths have also made an appearance as of late March, although their impact is still uncertain.