I used Bayer Advanced Tree and Shrub Control last year for the first time with excellent results for lacebug control on rhododendrons. Treating a large number of plants, however,is very expensive. The formulation I used was 1.47% imidacloprid. The recommended dilution for shrubs is 3 ounces per gallon per foot of height once a year. Another Bayer product contains .20% imidacloprid and the dosage is 1 ounce per quart per foot of height every six weeks.

The drawback of the .20 product is that it also contains a liquid fertilizer - unwise to use on rhodendrons after early July. I strongly believe that the 3 ounce per gallon per foot of 1.47% is unnecessary overkill for lacebugs, so I'm searching for information about what would be a more appropriate dilution for dealing solely with lacebug. Any help would be greatly appreciated.

Incidentally, last year I talked with one of the state entomologists as well as a local rhododendron nursery. Despite the best cultural practices, lacebug populations do seem to build up over time. Two years of good control seems to reduce the population to the point where treatment can be suspended for several years.