Weed Management Handbook

carfentrazone-ethyl (Aim EC or several trade names, 2 lb ai/gal)

Foliar active

Rate for the preplant timing application Up to 0.031 lb ai/A (2 fl oz/A carfentrazone-ethyl)

2,4-D ester (Weedone LV 6 and many others)

Rate For conifer release apply 0.95 lb ae/A to 2.75 lb ae/A (22 to 64 oz/A product). For site preparation apply 2.75 lb ae/A to 3.78 lb ae/A (44 to 88 oz/A product).

Time For conifer release apply before conifer budbreak in spring. See remarks for Douglas-fir release. For site preparation apply when susceptible plants are leafed out and developing.

Broadcast applications by helicopter, and in some cases backpack sprayer or ground equipment, can be the most effective and often least costly way to cover steep ground or tall vegetation. Uniform applications of precise herbicide rates per acre can result in good vegetation control during site preparation and safe conifer release with minimal injury potential.

triclopyr ester (Garlon 4 Ultra, Garlon 4, Element 4, Triclopyr 4, and others)

Rate 10-20% product v/v in oil carrier for low volume basal applications in an approximately 15-inch band on basal bark portions of tree or shrub stems. See remarks below for other rates and treatments.

glyphosate (Roundup Custom, Aquamaster and others)

Rate 50% product concentration v/v in water for stem and stump treatments. For stem treatments make at least one cut per inch of tree diameter with an ax or similar tool and apply one ml of solution per cut. For stump treatment apply a narrow band of solution completely around the cambium just inside the bark.

2,4-D ester (Weedone LV 6 and others)

Rate 5.5 pints/100 gal product v/v in water)

Time Apply when broadleaved weeds are small in the spring for best results. For woody plants treat when they are active from spring through summer. Avoid contact with conifers especially when they are actively growing.

In some instances, weeds and brush can be suppressed or controlled with non-herbicide treatments or used in addition to chemicals. Site preparation treatments such as machine scarification, slash piling, or prescribed burning can eliminate or temporarily suppress brush and weeds and set up conditions that allow for more conservative use of herbicides later in the life of a plantation.

The following is adapted from a Weed Report from University of California Weed Research and Information Center (2013) for control of tree of heaven (used by permission) https://wric.ucdavis.edu/information/natural%20areas/wr_A/Ailanthus.pdf.

Once native trees and shrubs are planted, it will be necessary to prevent growth of annual and perennial weeds for several years while the seedlings become established. Left unchecked, weeds emerging from the weed seed bank or encroaching from adjacent lands can rapidly reestablish. A rebounding weed community can compete with seedlings and reduce both survival and growth and also build up cover for voles, which can be very destructive to young plantings.

The purpose of site preparation is to clear the planting area of existing vegetation that will get in the way of planting and weed control activities, and to kill established perennial weeds that will compete with the new planting for water, light, space and nutrients.