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homeowner formulations of imidacloprid, which are limited by the label to one applica- tion per year. Homeowners wishing to protect trees larger than 15-inch DBH shouid con- sider having their trees professionally treated. Treatment programs must comply with any limits specified on the label regarding the maximum amount of insecticide that can be applied per acre during a given year. Syst,;,'!"n:c ir'~J(;ct1cid;:",?, Emamectin benzoate. In several inten- sive studies conducted by MSU and OSU researchers, a single injection of emamectin benzoate in mid-Mayor early June pro- vided excellent control of EAB for at least two years, even under high pest pressure. For example, in a highly-replicated study conducted on trees ranging in size from 5- to 20-inch DBH at three sites in Michigan, untreated trees had an average of 68 to 132 EAB larvae per m' of bark surface, which represents high pest pressure. In contrast, trees treated with emamectin benzoate had, on average, only 0.2 larvae per m', a reduc- tion of > 99 percent. When additional trees were felled and debarked two years after the emamectin benzoate injection, there were still virtually no larvae in the treated trees, while adjacent, untreated trees at the same sites had hundreds of larvae. In two OSU studies conducted in Toledo with street trees ranging in size from 15- to 25-inch D8H, a single application of emamectin benzoate also provided excel- lent control for two years. There was no sign of canopy decline in treated trees and very few emergence holes, while the canopies of adjacent, untreated trees exhibited severe decline and extremely high numbers of emer- gence holes. One study suggests that a single injection of emamectin benzoate may even control EAB for three years. Additional studies to further evaluate the long-term effectiveness of emamect;n benzoate are underway. To date, this is the only product that controls EAB for more than one year with a single application. In addition, in side-by-side comparisons with other systemic products (neonicotinoids), emamectin benzoate was more effective. Herms. McCullough, Smitley, Sadof, Williamson, Nixon Imidacloprld . Trunk injections with imidaclo- prid products have provided varying degrees of EAB control in trials conducted at different sites in Ohio and Michigan. In an MSU study, larval density in trees treated with Imicide" injections were reduced by 60 percent to 96 percent, compared to untreated controls. There was no apparent relationship between efficacy and trunk diameter or infestation pressure. In another MSU trial, imidacloprid trunk injections made in late May were more effective than those made in mid-July, and IMA-jet" injections provided higher levels of control than did Imicide", perhaps because the IMA-jet" label calls for a greater amount of active ingredient to be applied on large trees. In an OSU study in Toledo, IMA-jet" provided excellent control of EAB on 1 S- to 25-inch trees under high pest pressure when trees were injected annually. However, trees that were injected every other year were not consistently protected. In a discouraging study conducted in Michi- gan, ash trees continued to decline from one year to the next despite being injected in both years with either Bidrin (Inject-A-Cide B"l or imidacloprid. The imidacloprid treat- ments consisted of two consecutive years of Imicide" (10% imidacloprid) applied using Mauget" micro-injection capsules, or an experimental 12% formulation of imidaclo- prid in the first year followed by PointerTM (5% imidacloprid) in the second year with both applied using the Wedgle™ Direct- Inject™ System. All three treatment regimes suppressed EAB infestation levels in both years, with Imicide" generally providing best control under high pest pressure in both small (six-inch DBH) and larger (16-inch DBHl caliper trees. However, larval density increased in treated and untreated trees from one year to the next. Furthermore, canopy dieback increased by at least 67 percent in all treated trees (although this was substantially less than the amount of dieback observed in untreated trees). Even consecutive years of these treatments only slowed ash decline under severe pest pressure. In another MSU study, ACECAP" trunk implants (active ingre- dient is acephate) did not adequately protect large trees (greater than 15-inch DBH) under high pest pressure. EAB larvae damage the vascular system ofcthe tree as they feed, which interferes with movement of systemic insecticides in the tree. -'