Herbicide site preparation isn’t always possible before establishing a new plantation due to factors like the timing of harvest completion, lack of competition, weather conditions, or scheduling conflicts. However, regardless of these obstacles, early pine release can provide an effective solution.
In young plantations, herbaceous weeds and woody competition can significantly impact the diameter and height growth of seedlings. While herbaceous weed control treatments are generally ineffective against woody species due to the low herbicide rates used, stump sprouts from species like oaks, sweetgum, and red maple can grow vigorously, fueled by their large root systems. Without adequate control of woody vegetation, pine seedlings can quickly become shaded and lose vigor as they compete for sunlight, water, and nutrients.
RESEARCH INSIGHTS
A comprehensive study conducted across the Southeast found that controlling hardwood vegetation at the time of planting (pine age zero) resulted in a gain of 1.6 m² of pine basal area for each square meter reduction in hardwood basal area by age eight. Although the increase in pine basal area per unit of hardwood controlled was less significant when treatments were applied at ages 1, 2, and 3, it still averaged 0.76 m². Pine responses to woody control at ages 4 and 5 were similar to those observed during site preparation at age eight, and these responses are expected to increase with the stand’s age. While pine response to herbaceous vegetation control is typically quick, the response to hardwood vegetation control is slower but continues to impact growth throughout the rotation.
A ten-year study in Virginia further demonstrated the long-term impact of hardwood control on loblolly pine growth. Herbicide release at age two increased pine volume productivity by 55% compared to no treatment. Although pine growth response was higher when site preparation was performed (65%), the release treatment still provided a significant boost in growth.
EARLY PINE RELEASE TREATMENTS
Early pine release treatments primarily target woody competition and are typically applied starting now through November, to stands 2 to 7 years after planting. These treatments are usually administered by helicopter, with a total spray volume of 10 gallons per acre. In smaller stands where woody competition is less than 10 feet tall, ground backpack applications can be used.
RECOMMENDED PRODUCTS
Several herbicides are well-suited for early pine release. Arsenal AC and Escort XP offer excellent control of a wide range of woody vegetation as well as herbaceous weeds, with loblolly pine showing high tolerance to these herbicides. However, slash and longleaf pines are less tolerant, requiring lower application rates. There are also age and timing restrictions when releasing longleaf and slash pine, so it is essential to read and follow label directions carefully to ensure the correct rates are applied.
Azelis A&ES has experienced representatives that can help you make the right decision for your land management objectives. We are ready to provide you with a safe and effective solution. Talk to one of our technical experts to get started today!