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New Survey of Southern Tree Pests

Steven D. Frank

N.C. State University

 

Tree care professionals are well acquainted with Integrated Pest Management and try to incorporate IPM into their practices. The problem is that they do not have many IPM tools to work with. Once you find pests, how many is too many? Is there a threshold? Probably not.

 

It takes research to develop scouting techniques and management thresholds based on pest density. Unfortunately, grant funds to study urban trees and develop IPM tactics are scarce. Therefore, it is important to document research priorities so when funding comes along we can use it to greatest benefit.

 

I conducted a survey of research, extension, and tree care professionals to identify the most important southern tree pests. Participants were also asked to identify research and extension priorities. You can read the complete report here. I will touch on results of the pest survey and address research and extension priorities in a future newsletter article.

 

The survey listed 6 pest categories: bark suckers, leaf suckers, defoliators, borers, gallers, and mites. Participants rated each pest category from 0 (non-pest) to 3 (severe pest) for 10 tree genera. Acer and Quercus had the most diverse pest complexes. The most severe group on Acer was scales like gloomy scale, Japanese maple scale, terrapin scale, and cottony maple scales.

 

On oak trees, scales were outranked by defoliators like cankerworms and orange-striped oakworms and by gallers. Galls like horned oak gall can be major problems but management is limited our poor understanding of their biology. Oaks also host an array of scale insects such as Lecanium spp., obscure scale, and oak eriococcid scale that can reduce their growth and condition.

 

Some tree genera,such as Lagerstroemia, Platanus, and Liriodendron, included a single tree species with few pests. Sometimes lone pests like tulip poplar aphids become very important pests, covering sidewalks with honeydew and prompting consumer complaints. Crape myrtles, which used to have one primary pest, crape myrtle aphid, now also have crape myrtle bark scale which is spreading throughout the south and is far more damaging.

 

More funding will require pressure from consumers and tree care industries to acquire. In the meantime, documented priorities help secure the limited funding that exists and use it efficiently.