Forest
Stewardship News Release
June
21, 2005- For Immediate Release
Contact: Allyson
Muth , Phone: 814-863-0401 E-mail: abm173@psu.edu
Herbicides and Forest Vegetation Management
Written by: Dave Jackson, 814-355-4897, drj11@psu.edu
Across the state there are a number of problems that are increasing the need for vegetation management and the use of forestry herbicides. These problems include: vegetation that interferes with forest regeneration, poorly planned and executed timber harvesting practices, declining pulpwood markets, and increasing invasive plant species abundance. Herbicides, properly used, have become an important tool for forest landowners when managing their woodlots.
Herbicides are a proven safe and effective method for managing forest vegetation and are appropriate for achieving many objectives, including: regeneration establishment, elimination of competing trees for increased timber production, enhanced wildlife habitat, non-native plant control, and road and facility maintenance. When properly applied, herbicides can help to increase property value, productivity, aesthetics, and utility. However, understand that there are choices. A well-developed and implemented integrated pest management plan will include alternative vegetation control approaches.
No single herbicide, rate, or application method works for all vegetation management needs. Each situation requires advanced assessment to ensure that the safest, most efficient, and cost-effective control program is chosen. For a given situation the soil type, plant species, density, and size of vegetation to be removed affect the herbicide prescription. Additional factors such as time of year and weather conditions are important because they affect plant growth, herbicide uptake, and translocation. Always carefully read and follow the product label directions, precautions, and restrictions before applying any pesticide.
What follows is a summary of the most common forestry herbicide application methods and their uses.
Cut Surface
Treatments
1. Frill Girdle (Hack & Squirt)
Use hatchet, machete, or similar device to make a frill or cut at a downward
angle at proper spacing, following label recommendations. Cuts should
penetrate through the bark into living cambium tissue (the wood next to
the bark) and produce a cupping effect to hold herbicide. Spray, using
squirt bottle, measured quantity into cuts. Do not allow material to run
out of cut. Not recommended for use during heavy sap flow in spring.
Uses: Generally used to control individual trees over 5 inches in diameter
2. Cut Stump
For water soluble herbicide mixtures spray or paint the cambial area (the
wood next to the bark) of freshly cut stumps immediately after cutting.
If using an oil soluble mixture, treatments can be applied to stumps up
to one month following cutting. In the latter case, spray the sides of
the stump to the root collar and the cambium area around the entire circumference
of the cut surface until thoroughly wet, but not to the point of runoff.
Uses: Used to control re-sprouting of cut hardwood stumps
Basal Bark
Treatments
Using a low-pressure backpack sprayer, thoroughly wet the lower 12-15
inches of the stem completely around tree including the root collar area.
Do not spray to the point of runoff.
Uses: Generally used for controlling thin barked trees when they are less
than 6 inches in basal diameter
Foliar Broadcast
and Spot Treatments
Using aerial or ground spray application equipment, including helicopter,
skidder, or backpack sprayer, mist herbicide mixture onto the foliage
of targeted plants. Direct spray to evenly cover plant foliage. Do not
spray to the point of run-off.
Uses: Used to control many woody plants, herbaceous weeds, grasses, and
vines.
All of us need to be concerned about the long-term impacts of our forest management practices and the use of herbicides. After reviewing the chemical properties and product safety we can draw the conclusion that proper use according to the label may improve forest productivity and not adversely affect biodiversity. Used properly the environmental impacts of forestry herbicide applications are minimal because:
1. Forestry herbicides are applied at very low rates (2 oz. to 2 qts.) per acre and on a very small percentage of the land annually.
2. Generally only one application is made over an 80 to 100 year rotation for hardwood regeneration establishment.
3. Forestry herbicides are very low in acute toxicity. Of 27 forestry herbicides examined, LD50 values ranged from 1000 to >5000 mgs/kg classifying them as either only slightly toxic or practically nontoxic.
4. Forestry herbicides do not bio-accumulate in the food chain. When ingested, these chemicals pass very quickly through the body and are excreted in urine and feces.
5. Forestry herbicides are biodegradable and do not persist in the environment. All of these chemicals have relatively short half-lives and undergo biological decomposition.
6. The potential human
health risks from forestry herbicides are negligible. They are safer than
manual and mechanical methods of vegetation control.
(Revised from: McNabb, K. 1997. Environmental Safety of Forestry Herbicides,
Alabama Cooperative Extension System)
These points support the proper use of forestry herbicides. Despite relatively low risk to humans, animals, and the environment it is essential to practice care and environmental stewardship during application to ensure continued product availability. Before applying any forestry labeled herbicide be sure to consult a natural resource professional and remember to always read and follow the label; it is a legal document.
The Pennsylvania Forest Stewardship Program provides publications on a variety of topics related to woodland management for private landowners. For a list of free publications, call 1-800-235-WISE (toll-free), send e-mail to , or write to: Forest Stewardship Program, Forest Resources Extension, The Pennsylvania State University, 320 Forest Resources Building, University Park, PA 16802. The Pennsylvania Bureau of Forestry and USDA Forest Service, in partnership with the Penn State's Forest Resources Extension, sponsor the Forest Stewardship Program in Pennsylvania.
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