Summer and early fall means that site preparation season is here for landowners interested in establishing new pine plantations during the fall and winter months.
Unwanted or volunteer pine seedlings and saplings are typically considered a nuisance on sites that have been clearcut and where planting of high-quality genetically improved pine seedlings is planned. A landowner has little control of density and stocking of volunteer pines and, if left on site, control may require costly precommercial thinning or woody release treatments. Cutover sites that previously had mature loblolly pine plantations with canopy gaps or clearcuts near to existing pine plantations can all be likely areas for volunteer pine establishment.
This is especially true if a periodic prescribed burning regime was not previously practiced in the stand that is to be regenerated. Pine seed can be spread by wind several hundred feet from mature loblolly pines due to their light weight and the winged design of the seed. Volunteer loblolly pine seedlings are the most frequently encountered pine species because the species is the most prolific seed producer of all the southern pines. Good seed crops typically occur every 3-6 years, and pure, well-stocked stands may produce 80,000 or more seeds per acre.
Another problematic species in north Georgia is Virginia pine. Virginia pine, while not as prolific of a seed producer as loblolly pine, can also have good seed crops as often as every three years and may have good crops in successive years. Seed crops typically range from 6,000-40,000 seeds per acre. Bare mineral soil exposure associated with timber harvest machinery, mechanical site preparation, and soil exposure after a prescribed fire can create good seed germination conditions for unwanted pine seedlings.
Herbicide options are more limited for controlling pines than hardwoods. Commonly used site preparation herbicides such as hexazinone (e.g. Velpar L) and imazapyr (e.g. Chopper Gen II or Arsenal AC) do not adversely affect volunteer pines. Triclopyr, glyphosate, fosamine, and saflufenacil are all appropriate herbicides for controlling volunteer pines.
New herbicides and tank mixes are also currently being tested.
- Triclopyr is labelled for pine control and can be tank mixed with imazapyr (only ester triclopyr formulations can be mixed with imazapyr) for improved hardwood control. Six-pound ester triclopyr products (e.g. Garlon XRT) should be applied at 2 qts/ac and four-pound products should be applied at 3.2 qts/ac.
- Glyphosate (e.g. Accord XRT II) is the most commonly used and cheapest herbicide used to control volunteer pine. In addition, glyphosate can be tank mixed with imazapyr or triclopyr to improve the spectrum of control. Glyphosate application rates for volunteer pine control range from 3.5-6 qts/ac depending on a product’s formulation.
- Fosamine (e.g. Krenite S) is another option for volunteer pine control. This herbicide must be applied at high rates of about 4-6 qts/ac for good volunteer pine control without burning making it a more expensive option compared to triclopyr and glyphosate.
- Saflufenacil (e.g. Detail) can be added at a rate of 2 oz/ac to glyphosate tank mixes to reduce the amount of glyphosate needed by about 20%. Saflufenacil is an expensive herbicide, but recent trials for volunteer loblolly pine control have been promising when it is tank-mixed with glyphosate.
Good foliage coverage is required for adequate control of volunteer pines. For aerial applications using a helicopter, 15 gal/ac of water should be used and for ground applications 25-30 gal/ac. In addition, a nonionic surfactant or methylated seed oil should be added to improve herbicide foliage absorption and penetration. When prescribed burning is not preferred or cannot be completed on a site due to state regulations or liability issues, herbicide options are available for volunteer pine control.
—David Clabo, Silviculture specialist
The information contained herein is for educational purposes only. Reference to commercial products or trade names is not an endorsement by the University of Georgia nor is any discrimination intended against other products which may also be suitable and have label clearance.