Live Oak Midge Gall Infestation is a new problem in Louisiana. Scientists at SU Ag Center, Yadong Qi, professor of urban forestry and her doctoral graduate assistants, Vanessa Ferchaud, and Shong-sheng Li, have been monitoring the live oak midge gall infestation phenomenon in Baton Rouge since spring 2009.

"The gall infestation is caused by Arnoldiola atra Gagne, a tiny in-sect (about 2 mm long with a single pair of wings) called "gall midge." The pest was first discovered in Texas and described by R. J. Gagne and E. G. Riley in 1999 as a new species to America and its gall was considered as a new introduction into Texas as well as to the US. Now, this pest and its signature gall have shown up in our area," explains Qi.

The SU researchers first noticed this unusual gall in February 2009. They surveyed the SU campus and found that majority live oak trees have been infested by this gall.

"Though tiny, this pest appears to be quite aggressive and has caused a widespread and massive gall infestation on live oak trees throughout the Baton Rouge area. The lack of natural predators may have been the main reason for this pest to be as invasive as it has been," said Qi.

According to Brian Chandler, an Area Extension Forester at LSU, this live oak gall has been seen at least in six parishes in Louisiana.

"The gall midge population attacks the live oak buds and destroys them by making massive budlike cluster rosette galls. The galls are woody at the base. They compete for water and nutrients and add weight to the trees, causing die-back of branches and decline in tree vigor," said Qi.

Through a year of data collection, the SU researchers have gained a better understanding of the gall formation, biology and behavior of the gall midge, and its ecological impacts on the live oak trees.

They have presented their findings to the public through seminars and outreach programs. They have been providing technical consultation and working with urban forestry professionals at SUBR, LSU, BREC, LA Country Club, and chemical companies to develop effective management strategies to bring this pest under control. For more information please contact: Yadong Qi, Professor of Urban Forestry at 225-771-2262 ext 269 or yadong.qi@gmail.com

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