Tuesday, May 14, 2013

Are Hack-and-Squirt Treatments a Viable Option for the Control of Beech Understories

Dense understories of beech can
inhibit regeneration success.
This is follow-up to a recent post I made concerning control of understory tree species, in particular American beech (Fagus grandifolia).  In a post dated March 11, 2013 I highlighted a new fact sheet I recently published entitled Using Basal Bark Herbicide Applications to Control Understory Tree Species.  In the fact sheet I made note of findings of a basal bark herbicide rate study in which I found nearly 100% control of beech stems using a 5% concentration of triclopyr as Garlon 4.  As I put in this study and through some additional work on my own I began to wonder about the practicality, effectiveness, and cost of basal stem treatments as a means of controlling understory beech sprouts.  I began to wonder if it might not be more effective to utilize a hack and squirt method instead.  I began to look at published studies conducted by the Forest Service and others.  Below are the results of two such studies.  The results are quite telling.  Also see blog post Beech Control: Options for Management dated June 21, 2012.

In a 2004 Kochenderfer et. al. published a study entitled Preharvest Manual Herbicide Treatments for Controlling American Beech in Central West Virginia.  In this study researchers compared two basal area reduction methods; hack-and-squirt using a 50% solution of glyphosate as Accord and basal spraying with a 10% solution of triclopyr as Garlon 4.  All treatments were applied in late August.  One year after treatment almost complete control was achieved with both application methods.  Some of their findings include:
- Hack-and-squirt injection method was the cheapest and most target-specific way to control stems greater than 1 inch dbh.
- Hack-and-squirt of all trees greater than 6 in. dbh had the added advantage of controlling about half of existing beech stems less than 1 inch dbh and 21.6% of those 1-5.9 in. dbh.
- Basal spray applications are more costly but are better adapted for treating small stems, those less than 1 in.dbh.

In a follow-up study published in 2012 entitled, A Comparison of Two Stem Injection Treatments Applied to American Beech in Central West Virginia, Kochenderfer et. al. compared the efficacy of hack-and-squirt treatments using 50% glyphosate as Razor Pro and 6% imazapyr as Arsenal on injected trees and their associated root sprouts.  In this study the two hack-and-squirt treatments were applied to all beech stems 1 in. to 9.9 in. dbh at the rate of 1 incision per inch of dbh.  All treatments were applied in September to maximize translocation to roots.  The results were evaluated 1 year following treatment.  The findings of this study include:
- Both treatments controlled 100% of the treated stems.
- Arsenal (imazapyr) controlled 77% and Razor Pro (glyphosate) 64% of all untreated beech stems 1 ft. tall to .9 in. dbh.
- The average number of untreated beech stems controlled per treated stem was 33% higher for the Arsenal (imazapyr) plots.
- It cost almost twice as much to control each stem on the Razor Pro (glyphosate) plots.
- None of the black cherry or red maple crop trees were damaged by either of the treatments.

To summarize:  
Advantages of Hack-and-Squirt:
1. Considered one of the least expensive manual herbicide application methods.
2. Is a target specific treatment.
3. Can be used on all stems greater than 1 in. dbh.
4. Can be used on steep topography and on small ownerships.
5. Can be used without impacting advanced regeneration.
6. Treatments containing imazapyr or glyphosate will control a large proportion of attached root sprouts on root suckering species like American beech. 

Disadvantage of Hack-and-Squirt:
1. Use is restricted to the growing season, June 1 to Nov 1, as sap flow frequently occurs between Nov 1 and leaf out.

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