There is limited information on site preparation herbicides for pine plantations in Alabama. This Extension publication will help forest landowners and forestry professionals gain a better perspective on forestry herbicides available for site preparation. We compiled a list of site preparation herbicides and included: rates to apply them, species of pine, target species, resistant species, time of year for application, soil activity, and when to replant pine seedlings.
It is important to control competing vegetation prior to planting pine seedlings. Competition control will improve seeding survival and growth, along with future wood quality of pine plantations. If no competition control measure is conducted prior to planting, pine seedlings will be competing for nutrients, water, and sunlight with grasses, hardwoods, natural pine seedlings, other broadleaf species, and invasive plants. This can reduce the future economic value of the pine plantation. Chemical site preparation is a competition control measure and involves the application of herbicides. Herbicides are an effective method to control competition prior to planting pine seedlings and have been found to be cost-effective in pine plantation management. Remember, a pine is not just a pine. Be sure to follow herbicide recommendations for the pine species you are planting. Herbicides are often used in conjunction with prescribed burning to reduce competition and woody debris during site preparation. When planting longleaf pine, oftentimes you can apply the lower application rate for the herbicides recommended for longleaf plantings because prescribed fire can be used after planting. Longleaf can tolerate prescribed fire at a young age, whereas loblolly, slash, and shortleaf cannot tolerate fire at a young age.
Most forestry herbicides are non-restricted and can be purchased at local farm stores. It is important to read the label of each herbicide prior to every use and to keep records of application date, method of application, herbicide, and rate. Herbicide labels provide a list of the personal protective equipment (PPE) required, active ingredient, rate of application, soil activity (effects replanting timeframe), target and resistant plant species, time of year for application, and if a surfactant is recommended. Herbicide labels are found on each herbicide container but can also be found online at www.cdms.net. This website is very helpful to review herbicides prior to purchasing. After going to the website, click on the Label Database+ link, enter the herbicide trade name in the search bar, click on the herbicide, and select label.
It has been found that when the correct herbicide(s) are applied at the proper rate, pine seedlings will have increased survival and growth after planting. When utilizing a tank mix of herbicides, be sure the labels do not prohibit mixing and follow the most restrictive label. The label is the law. For a better understanding of forestry herbicides to use for site preparation of pine plantations, we have compiled a table of herbicides to make it easier to know which herbicide(s) to select and rates to apply them (Table 1).
Table 1. Site Preparation of Pine Plantations
Adapted from: 2017 Quick Guide to Forestry Herbicides Used for Softwood and Hardwood Site Preparation and Release. NC State Extension
|Active Ingredient||Herbicide Trade Name(s)||Time of Year||Pine Species||Rates||Surfactant||Soil Activity||Target Plants||Resistant Plants||Notes||Replanting Timeframe|
|Imazapyr||2 lb. Arsenal, Chopper Gen 2 4 lb. Arsenal AC, Polaris AC||Growing season once full leaf expansion of target species||Loblolly, Longleaf, Slash, Shortleaf||Loblolly, Longleaf, Shortleaf 2 lb. - 48 - 80 oz/ac 4 lb. - 24 - 40 oz/ac|
Slash 2 lb. 40 - 64 oz/ac 4 lb. 20 - 32 oz/ac
|If not already included: Non-ionic surfactant 0.25% v/v OR Methylated Seed Oil - 1.5 to 2 pt/ac||High||Most hardwoods, annual and perennial grasses and forbs, Bermuda, fescue, crabgrass, dog fennel, pigweed, greenbriar, morning glory||Elms, woody legumes, wax myrtle, croton spp., rubus, buckeye, baccharis, pine, hickory||Rates may be excessive on well drained sites. On cutover sites, 48 oz or less may be sufficient. If treating old-fields sites with improved forages, 64 (32) oz/ac+ may be needed; expect a retreatment with glyphosate on resprouting improved forages.||Delay planting at least 60 days after imazapyr application. May need longer on sandy sites or when less than normal rainfall has occurred.|
|Glyphosate||Accord XRT II, Rodeo, Touchdown Total, Glyphosate 5.4, Touchdown Pro, Glyphosate 4 Plus||Growing season once full leaf expansion of target species||Loblolly, Longleaf, Slash, Shortleaf||4 lb. 1.5 - 8 qt/ac|
3 lb. 2 - 10.6 qt/ac
|If not already included, Non-ionic surfactant 0.25% v/v||None||Natural pine seedlings, most hardwoods (black locust, persimmon, sassafras, sumac, sweetgum, yellow-poplar), most annual and perennial grasses, and forbs||Red maple, oaks, ash, hickory, dogwood, rubus, greenbriar, Virginia creeper, trumpet vine||For good results, add to a tank mix for site-prep||Recommended to wait 3-7 days after application|
|Triclopyr||Element, Garlon 3A, Garlon 4,||During periods of active growth||Loblolly, Longleaf, Slash, Shortleaf||6.3 lb - 2.5 - 4 qt/ac|
4 lb. 4 - 6 qt/ac
3 lb. up to 2 gal/ac
|Non-ionic surfactant 0.25-0.5% v/v||Low||Most hardwoods, southern pine (natural pine), waxy species such as bay, gallberry, wax myrtle, and yaupon, forbs, dog fennel, pigweed, greenbriar, and morning glory, rubus||Grasses||Can be applied throughout the growing season, including late in the growing season. Wait 4-6 weeks after application for conducting a site- prep burn.||Wait at least 30 days to avoid conifer seedling injury|
|Metsulfuron Methyl||Escort XP, MSM-60||Apply after weeds have emerged or after undesirable hardwoods have broken winter dormancy and have reached the point of full leaf expansion||Loblolly, Slash||up to 4 oz/ac||Non-ionic surfactant 0.25 v/v||High||Wide range of annual and perennial broadleaf weeds and woody plants, kudzu, multiflora rose||Grasses, yellow poplar, loblolly pine||Longleaf not listed on label but not prohibited. Label states "In the absence of prior experience, in order to avoid unacceptable injury, other species should be planted on a small scale to determine safety before large-scale plantings are made."||Planting season following herbicide application|
|Sulfometuron Methyl||Oust XP||Before herbaceous weeds emerge or shortly thereafter||Loblolly, Longleaf, Slash||2 to 8 oz/ac||Non-ionic surfactant 0.25 v/v||Low||Annual grasses and forbs and certain perennial herbs||Bermuda, broomsedge, croton spp., trumpet vine, panicum's, natural pines, most hardwoods||Use a low rate on coarse-textured soils (i.e. loamy sands, sandy loams) and a higher rate on fine-textured soils (i.e. sandy clay loams and silty clay loams).||Planting season following herbicide application|
|Sulfometuron Methyl + Metsulfuron Methyl||Oust Extra||Before herbaceous weeds emerge or shortly thereafter||Loblolly, Longleaf, Slash||Longleaf and Slash 3-4 qt/ac|
Loblolly 3-5.5 qt/ac
|Non-ionic surfactant 0.25 v/v||High||Undesirable woody plants, vines, and many broadleaf weeds and grasses||Loblolly||Can be tank mixed with glyphosate, imazapyr, and triclopyr for applications in late summer to broaden undesirable hardwood control||Planting season following herbicide application|
|Imazapyr + Metsulfuron Methyl||Lineage Clearstand||Growing season once full leaf expansion of target species||Loblolly, Slash||up to 25 oz/ac but for target plants listed 8-16 oz/ac||Non-ionic surfactant 0.25% v/v OR Methylated Seed Oil - 1.5 to 2 pt/ac||High||Ash, blackgum, cherry, hawthorn, honeysuckle, hophornbeam, persimmon, oaks, sassafras, sweetgum, and vaccinium species. Suppresses blackberry, dogwood, elms, myrtle dahoon, hickory, and red maple||Burn only after adequate rainfall to allow for proper movement of herbicide into the soil||Planting season following herbicide application|
|Aminopyralid||Milestone||Anytime during the growing season||Loblolly, Longleaf, Slash, Shortleaf||up to 7 oz/ac||Non-ionic surfactant 0.25-0.5% v/v||Moderate||Rubus, morning glory, horseweed, pigweed, sicklepod, ragweed, wilding pines, boxelder, cherry, cottonwood, elm, maple, poplar, oak, hackberry, Russian and Autumn olive, salt-cedar, thistle, natural pines (except longleaf)||Grasses||Good natural pine control. Use caution when treating areas adjacent to susceptible and desirable species to avoid root uptake and possible injury when using Milestone or other soil active herbicides||Planting season following herbicide application|
|Clopyralid||Transline||Anytime during the growing season||Loblolly, Longleaf, Slash, Shortleaf||1/4 - 1 1/3 pt/ac||Non-ionic surfactant 0.25-0.5% v/v||Low||Certain broadleaf weeds including thistle, kudzu, sicklepod, morning glory, ragweed, coffeeweed, most legume specie||Most established grasses, woody plants, mustards, henbit, chickweed, kochia, lamb- squarters, pigweed, Russian thistle and field bindweed.||Use caution when wanting to retain plants in the legume family (such as locust, redbud, mimosa and lupine) and box elder, persimmon or sassafras||Planting season following herbicide application|
|Hexazinone||Velpar L, Velpar DF, Pronone Power Pellet||Early spring to early summer after bud break but before the foliage has hardened off||Loblolly, Longleaf, Slash, Shortleaf||Liquid-4-10qt/acDF -22/3-62/3lb./ac Power Pellet - 1,700 - 5,800 pellets/ac||Not advised||High||Most hardwoods, rubus, crabgrass, fescue, lespedeza, horseweed, dog fennel, annual and perennial rye grass, black cherry, blackgum, dogwood, elm, hawthorn, hickory, oaks, red maple, sweetgum and sumac||Yellow-poplar, eastern redcedar, sassafras, blackgum, hollies, American beautyberry, bermuda grass, white snakeroot, broomsedge, Johnson grass, sicklepod, trumpet vine, morning glory||Herbicide applied to the soil. Application rates are dependent on soil texture. Use the lower rates on coarse textured soils and soils low in organic matter. Requires 1/4 - 1/2 inch of rainfall to activate. Allow foliage to defoliate twice before conducting a site- prep burn or drum chopping.||Planting season following herbicide application|
|Dicamba||Vanquish||During periods of active growth||Loblolly, Longleaf, Slash, Shortleaf||1 qt/ac maximum||Non-ionic surfactant 0.25-0.5% v/v||Moderate||Undesirable conifers, annual and perennial broadleaf weeds, woody brush, multiflora rose (when dormant)||Planting season following herbicide application|
|Fosamine||Krenite S||Apply during the growing season; after full leaf out before fall coloration||Loblolly, Longleaf, Slash, Shortleaf||2-4qt/acwhen burning is allowed. 4-6 qt/ac with no burn||Non-ionic surfactant 0.25 v/v||Low||Postharvest control of natural pine and hardwood species for southern pine planting site preparation||Non-woody plants (usually) and waxy leafed species||Based on label recommendation of tank mixed product|
|Picloram||Tordon K, Trooper 22K (Restricted Use)||During periods of active growth||Loblolly, Longleaf, Slash, Shortleaf||2 qt/ac||Non-ionic surfactant 0.25-0.5% v/v||High||Annual and perennial broadleaf weeds, woody plants especially legumes and southern pine species (natural pines) and vines||Most grasses are resistant||Allow at least 6 months after treatment before planting pines|