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There has been some questions on herbicide options for newly planted pine sites.

I was asked about Longleaf pine, so listed below will be information base on this type. I will also attach some information on loblolly and slash. 

This information was discussed with Dr. David Clabo (UGA Silviculture Specialist)

There are a few good options for newly planted longleaf pine. Grass may be a serious competitor depending on what type of grass is present. Bermudagrass is a prime example. Another option that should be considered is dormant season burning, especially if the seedlings are in the grass stage and have not begun active height growth (silver looking candle present at the terminal bud). Longleaf pine seedlings in the grass stage are very tolerant of prescribed fire. Below is listed the herbicide, application rate, and highlighted weeds controlled by that herbicide or tank mix. All herbicides should be applied in 5-15 gal/acre of water unless stated otherwise. In addition these herbicides should be applied for herbaceous weed control during late winter or early spring before weeds reach a foot tall for optimum control.

  1. Oust XP (metsulfuron methyl)-apply at 2-4 oz/ac WITHOUT a surfactant, broad spectrum of broadleaf weeds including composites, weak on grasses. Do not use when soil pH is greater than or equal to 6.2.
  2.  Oust XP + Velpar L (hexazinone)-2-4 oz/ac Oust and 2-3 pints/ac Velpar without a surfactant, broad spectrum control of broadleaf weeds and most grasses but weak on bermudagrass and broomsedge. Again be careful of soil pH with Oust and the Velpar rate is dependent on soil texture (see label). Sandy soil textures are best for Velpar applications because less of it has to be used (it is fairly pricey).
  3. Milestone (aminopyralid)-apply at 7 oz/ac without a surfactant (fairly pricey herbicide). Controls blackberry, clover, coffeeweed, kudzu, marestail/horesweed, morning glory, partridge pea, pigweed spp., ragweed, sicklepod, vetch, wisteria.  Good on legumes. Some needle curing may be evident after application but seedlings grow out of it.
  4. Transline-(clopyralid)-apply at 11-21 oz/ac without a surfactant. May be applied later in the growing season over actively growing weeds (late spring into summer). Controls clover, coffeeweed, cocklebur, kudzu, marestail/horesweed, morning glory, partridge pea, ragweed, sicklepod, vetch, and wisteria.
  5. Arsenal AC (imazapyr) (be sure to purchase a 4 lb ai product WITHOUT a built-in surfactant: Arsenal AC and Polaris AC are two good options)-Apply 4-5 oz/ac without a surfactant. Grass and broadleaf weed control including, but not limited to: bahiagrass, barnyardgrass, bluegrass (annual, Kentucky), Bermudagrass, crabgrass, fescue, foxtail, Italian ryegrass, Johnsongrass, lovegrass, panicum (fall), sandbur, smooth brome, wild barley, wild oats, witchgrass, camphorweed, carpetweed, chickweed, clovers, cocklebur, dandelion, dogfennel, horseweed, goldenrod, knotweed, lambsquarters, milkweed, ragweed (common, giant), pepperweed, pigweed, plantain, pokeweed, purslane, pusley (Florida), shepard’s purse, stinging nettle, sowthistle, annual spurge, sunflower, tansymustard, wild carrot, wild parsnip, wild turnip. Be careful with application rates over-the-top of longleaf pine seedlings.

Here are some publications on each of the three pines for weed control