AUSTIN – If you live in South Central Texas and have noticed cedar trees turning brown, it is likely due to a new infestation of juniper budworms, said a Texas A&M AgriLife Extension Service entomologist.
“Many people in this area have noticed their Ashe juniper trees, commonly called cedar, turning brown,” said Wizzie Brown, AgriLife Extension integrated pest management program specialist for Travis County. “This most likely is being caused by juniper budworms. There was an outbreak of these insects in this area in 2002, and we have had another outbreak this year.”
The caterpillars feed on Ashe juniper foliage and build silken tubes on the branches of the trees, she explained. The tubes are typically on the tips of branches and are where the insect pupates.
Brown said while there had been no long-term damage to the trees resulting from the earlier outbreak, it is unknown what may happen to the trees due to the current outbreak.
“So far, I have had reports from Wimberley, Burnet, Austin, Bee Cave, Blanco, Oak Hill, Dripping Springs and thereabouts, so this outbreak seems to be mostly situated in the Hill Country area west of I-35,” she said.
Brown said Juniper budworms are a yellowish-green to green caterpillar with a brown head capsule.
Adult moths are a mottled brown color and blend well with dead Ashe juniper foliage.
“Adults rest on the host plant during the day and do not move unless disturbed,” she said. “Since the adults are moths, they can fly to a new area if need be, but tend to remain around the same tree unless something disturbs or threatens them.”
Drought may also play into any additional tree damage from this outbreak, she noted.
“The 2002 outbreak did not have lasting effects to the trees, but I’ve also seen samples that have had spider mites on them, which often pop up when conditions are dry. Usually when we have outbreaks of any insect it’s because certain environmental conditions favor the enlargement of that population. But if that may be the case with this juniper budworm proliferation, I’m unsure.”
Brown said if a pesticide treatment is desired, look for active ingredients such as Bacillus thuringiensis variety kurstaki, azadirachtin, also known as neem, or spinosad. It is also possible to removed infested branch tips by hand.
She suggested placing infested branches or tips into a bag and disposing of them instead of dropping them onto the ground where larvae and adults may continue to grow and reproduce.
“Products will work best on smaller caterpillars,” she said, adding that when using pesticides it is important to read and follow all label instructions. “In rural areas, it may not be feasible to manage the juniper budworms, especially on large parcels of land. Individual landowners may choose to treat prized trees on their property.”
For more information or help with identification, contact Brown at 512-854-96oo or firstname.lastname@example.org.