Leafminer showing up on garden mums

Mich. St. Univ. Extension educator Jeanne Himmelein reports that there are some parts of Michigan where leafminers (Liriomyza trifolii) have been identified on garden mums. The pest has a fairly short life cycle of 21-28 days under hot, humid conditions, which many parts of the country have recently experienced. She said this allows multiple generations to occur during the summer.  Once the temperature exceeds 83°F, the larvae begin to die.

The primary damage caused by leafminers on mums is the mining of the leaves by the larvae. The adults can be monitored using yellow sticky cards. The females prefer to lay their eggs on older leaf surfaces and tend to deposit them in the middle of the plant.

Mich/ St. Univ. entomologist David Smitley recommends Avid and Citation for control purposes. If adult flies are identified, control applications should be made to reduce female activity. 

 

Pictured: Michigan growers have reported increased activity of leafminers on their fall garden mum crops.

Photos courtesy of Ontario Ministry of Agriculture, Food and Rural Affairs