Brent from Richmond Va writes
I have approximately 150 feet of English Boxwood hedgerow that surrounds my side and back yard. Currently we are experiencing a white fly problem that is damaging the hedge. Ideally we would like to use an systemic Imidacloprid treatment solution (long lasting and pet safe). However all of the label instructions for products only indicate dosage based on height (ounces per height). It seems odd that a 5 foot tall shrub that is 1 foot in radius would take the exact same dosage as a 5 shrub that is 10 feet in radius. However, per the labels both are 4 feet high and get the same treatment - regardless of biomass. This problem extends to my hedge issue. How do I calculate the amount of product to use for a 5 foot tall hedge that is 150 feet long? Surely it is not all considered a single shrub? And surely each plant cannot be considered a separate shrub (approx 450 individual stems in that length). The former appears insufficient and the latter would be approaching the acreage limit of Imidacloprid per year. Thanks for your help.
You will need 0.1 to 0.2 fl. oz. (3 to 6 mL) of a product with imidacloprid, such as Adonis 2F, per foot of shrub height or 0.1 to 0.2 fl oz per inch of trunk diameter for trees. The amount of water that is used will vary depending on soil conditions and volumes that are easy for applicators to use. The minimum amount of water that should be used is 1 pint per foot of shrub height (or inch of trunk diameter for trees) but you may use 1 quart -1 gallon of water per foot of height (or inch of trunk diameter for trees) as well. Denser soils such as clay do not accept water as readily, so the lower volume of water is suggested. Since sandy soils can accept more water, using the higher volume of water is preferred. After the soil drench has been applied you should water it in with at east 1/2 inch of water. Note: Water simply acts as a carrier and it is important that even distribution of the product is achieved. Thus, more water may be used if the applicator feels runoff will not occur and proper penetration of the root zone is achieved. Insecticides applied to the soil are taken up by the roots and translocated throughout the tree or shrub. Root/soil drenches offer the advantage of requiring no special equipment to apply (other than a bucket or watering can). However, surface layers of organic matter, such as mulch or leaf litter, can bind the insecticide and reduce uptake. Before applying drenches, it is important to remove or pull back any mulch or dead leaves so the insecticide solution is poured directly on the mineral soil. It is also important to keep the soil around the tree or shrub moist for the next 7-10 days after applications to encourage uptake. We also recommend using a product with an active ingredient that is different than the soil drench for a foliage application while you are waiting for the Adonis to translocate through the hedges.
Answer last updated on: 05/21/2015
