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10 Arbor Age / June 2014 www.arborage.com TREE PEST MANAGEMENT TREE PEST MANAGEMENT B y R o b G o r d e n Managing invasive insects and diseases is of great importance to everyone in the plant health care fi eld, and to communities as well. While native tree species have co-evolved with native tree pests, reaching equilibrium over time, new pests and climate change have altered the norm. Native species are dying from pests that don't belong here or whose damaging impact has been enhanced by the changing climate. The National Invasive Species Council (NISC) defi nes invasive species as, "An alien species whose introduction is likely to cause economic or environmental harm, or harm to human health," adding that it is a species that is, "Non-native to the ecosystem under consideration." The emphasis is placed on risk of environmental harm, native species dislocation, or potential harm to humans or other native species. We must be better prepared with systems and processes to address invasive species and with our response when they arrive. Current state of affairs Invasive species are primarily introduced through the ac- tion of humans. According to Invasive.org, in 2010 there were 456 invasive insect species in the United States. That number has grown by 27 new species in just the last four years. Emerald ash borer (EAB), the most destructive tree pest ever brought to the United States, was identifi ed in 2002, but arrived as early as 1998 1 . New infestations may spread up to 14 miles annually. Gypsy Moths, which rampaged through New England in the 1980s, were controlled by fungi, wasps, and viruses. Other invaders include Rugose Spiraling Whitefl y in the southeast; Hemlock Woolly Adelgid (HWA); Japanese Beetle; Pinewood Nematode; and Polyphagous Shot Hole Borer, which attacks 200 species of trees including Sycamore, Avocado and Sweet Gum in California. Effects of climate change Our changing climate has allowed native and non-native tree pests to impact broader regions, to attack previously unaffected plant species, and to obtain highly destructive populations. Examples include the Mountain Pine Beetle, which has killed more trees than wildfi res; Spruce Beetle; Gold Spotted Oak Borer; Sudden Oak Death; and HWA. Increasing moisture in the east has amplifi ed the severity of leaf diseases, needle casts and assorted blights. Droughts in the west weaken native trees, permitting explosive insect damage. What is the role of science? The scientifi c community studying these invasive pests shoulders the burden of identifying the pest and its life cycle, and then concluding how to prevent it from destroying na- tive and urban forests. The challenges include research-funding limitations and delay in recognizing that a new pest has ar- rived. Pests have very specifi c annual life cycles, which must be studied. Experimentation with suitable treatment options, rates, and methods require years to reach scientifi cally verifi - able conclusions, while the destruction continues unabated. Do quarantines help? The USDA – APHIS (Animal and Plant Health Inspection Service) is the fi rst line of defense to prevent invasives from spreading in the United States. Their role is to eradicate these pests, not to manage them. If APHIS demonstrates success with containment and eradication, control remains with the agency. If the pest can't be eliminated, then management of the pest defers to local government, even if federal regulation continues. The Asian Longhorned Beetle (ALB) program has been one of APHIS's biggest successes. APHIS has treated 1.2 million trees against ALB, and removed many infested trees, eradicating it in several state outbreaks. The Emerald Ash Borer's life cycle makes detection dif- fi cult, and APHIS could not stop its spread. Quarantines were imposed, but its ability to hide in fi rewood means we are still enhancing its spread. It has hitchhiked across two-thirds of the United States in just 17 years. Enormous resources are applied to set up, manage, and educate on the "quarantine" for each new pest. Tree Pests Can we be better prepared for the next outbreak? The Challenge of Invasive