Extension Master GardenerSM Volunteers of Buncombe County

herbicides

Non-Native Invasive Plants: Tree of Heaven

Once you learn about non-native invasive plants they seem to be everywhere! One of the worst of these—Ailanthus altissima—has the misleading common name “Tree of Heaven.” Introduced as an ornamental, Ailanthus is an attractive, fast-growing tree—but when cut back it can sprout up more than 10 feet a year! Water and wind can spread seeds that will grow new trees as tall as 6 feet their first year.

Ailanthus trees produce a lot of pollen and all parts of the tree can produce skin irritation in some individuals. If that doesn’t give you pause, we now have a new reason to double down on eliminating this invader: it is the preferred host tree for an exceedingly destructive insect, the spotted lanternfly (Lycorma delicatula), which may be making its way south! Removing Ailanthus now will make North Carolina less hospitable to this planthopper, which is a major pest of many fruits, including apples and grapes.

Adult Male Lanternfly

How to know if you have tree of heaven?

Characteristics to look for:

  • Bark: Smooth bark that looks somewhat like cantaloupe skin.
  • Leaves: Each leaf has from 10 to 40 leaflets with smooth edges, except for 1 to 2 “teeth” at the bottom of each leaflet. Leaves have a very strong peanut-butter odor.
  • Flowers: Yellowish flowers April through June.
  • Seeds: Winged seed pods in large clusters that may stay on the trees in winter.

Management
Tree of heaven is difficult to control because of its extensive root system and re-sprouting ability. Success depends on treatment timing and following up the next year. Be sure to wear gloves and other protective clothing when removing tree of heaven because of the possibility of allergic reactions.

Mechanical

  • Hand-pull young seedlings as soon as they are large enough to grasp. They are best pulled after a rain loosens the soil.
  • Remove the entire root because small root fragments are capable of generating new shoots.
  • Note that root suckers are easily confused with seedlings and are nearly impossible to pull by hand.
  • Although cutting down a tree of heaven will cause it to re-sprout and sucker, you may want to prune out limbs during the winter after leaf fall.
  • If seed clusters are present on cut limbs, collect, bag, and dispose of in heavy trash bags so they will not sprout have a chance to sprout.

Chemical

  • Herbicides containing the active ingredient triclopyr are effective. Apply all chemical treatments between July 1 and when the tree begins to show fall colors.
  • When removing a tree of heaven, use foliar herbicide sprays where tree height and distribution allow effective coverage without unacceptable contact with nearby desirable plants.
  • Treat the foliage with an herbicide first, allow 30 days for it to take effect before cutting the tree down.

 Native alternatives for Ailanthus altissima

Suggested by NCSU’s “Going Native” website:

  • Hickories (Carya)
  • Fringetree (Chionanthus virginicus)
  • Green Ash (Fraxinus pennsylvanica)
  • Smooth Sumac (Rhus glabra)

                              Article by Debbie Green, Extension Master GardenerSM Volunteer

 For more information:

Identifying:
https://projects.ncsu.edu/goingnative/howto/mapping/invexse/treeofhe.html

More on landscaping with native alternatives:
https://projects.ncsu.edu/goingnative/index.html

Spotted lanternfly watch:
https://ipm.ces.ncsu.edu/wp-content/uploads/2018/10/SpottedLanternflyPestWatch.pdf?fwd=no

 

Investigate Before You Invest in Any Pesticide

Deciding among the plenitude of pesticides on garden center shelves, all in colorful packages with large print promises, can be challenging. When buying a pesticide, you’re making an investment. And, as in making any purchase, you want to know what you’re investing in before you put your money down.

Oregon Dept of Agriculture_Pesticide Inspection_CC BY-NC-ND 2.0_Flickr
Investigate before deciding if, when, what, and how to use a pesticide.

Plan ahead before you buy
Are you sure you have a problem that a pesticide can solve? Have you identified the real cause? Weather can lead to some strange plant/environmental reactions, so make sure you have the correct problem identified. An insecticide won’t do you much good against a fungus! If you’ve experienced the problem in the past, investigate and exhaust alternative solutions before you start searching the pesticide shelves.

Read the label before you invest
The pesticide label is the contract between you and the product’s supplier. The label tells you what the product will do and what you must do to make it work effectively.

Like any legal document, the label must carry some words that have very specific meanings. On every pesticide label, you’ll find one of these three words in large, bold print: 

  • CAUTION: The product is slightly toxic if eaten, absorbed through the skin, or inhaled, or it causes slight eye or skin irritation.
  • WARNING: The pesticide is moderately toxic if eaten, absorbed through the skin, or inhaled, or it causes moderate eye or skin irritation.
  • DANGER: This pesticide is highly toxic by at least one route of exposure. It may be corrosive, causing irreversible damage to the skin or eyes. Alternatively, it may be highly toxic if eaten, absorbed through the skin, or inhaled. If this is the case, then “POISON” must also be included in red letters on the front panel of the product label.

    Malathion Directions_by Chris_Alberti_CC BY 2.0_Flickr
    Pesticide label tells what product does, explains how to use effectively, and gives warnings.

Be knowledgeable about product application

  • Will you need to mix the product with water or do you want to spend a little more for the convenience of a ready-to-use concoction?
  • What equipment will you need? Rubber gloves? A sprayer? Make sure your sprayer is in good working order by testing it with water on the driveway . . . not on valuable plants!
  • If you need to measure, make sure you have a measuring cup used only for pesticides! And rinse well after every use. Even a tinge of herbicide can work havoc with roses!
  • Refresh your memory and adhere to the contract uses of the product. What does it say about application under certain weather conditions—wind, temperature, precipitation? Does the product advise on use near water bodies or when pollinators are present?

Keep a pesticide inventory
Take a rainy afternoon to inventory your pesticide collection! Check the expiration dates and plan environmentally safe disposal of out-of-date pesticides. Maintain a pesticide usage record, including plants, problems, timing, and effectiveness. Your attention to up-front investigation and appropriate usage is a good investment, not only in any pesticide but also in your garden. 

Article written by Glenn Palmer, Extension Master GardenerSM Volunteer.

Time to Maintain: Stop Crabgrass Before It Starts

Act now to stop dreaded crabgrass from invading your lawn this spring and summer. Late February to late March—around the time Bradford pear trees start to bloom, but before the dogwoods—is the ideal time to apply a pre-emergent herbicide. It’s important to spread the pre-emergent and to create an herbicide barrier for the roots and shoots of those crabgrass seeds before they germinate. If germination has occurred, applying a pre-emergent is not effective as a weed killer.

crab grass_wintersoul1_CC BY-NC-ND 2.0
Digitaria sanguinalis or crabgrass weed

A summer annual weed
Crabgrasses are summer annual weeds that germinate as temperatures warm up in the spring, grow through the summer, then set seed and die in the fall. Once established, crabgrasses can quickly spread and devastate your lawn.

Using a pre-emergent herbicide
An application of a pre-emergent herbicide will last about 6 to 12 weeks, depending on the chemical used. Oryzalin and trifluralin are common pre-emergent ingredients. In addition to crabgrass, these herbicides will also control other summer annual weeds such as cocklebur, goose grass, and purslane. You can use most pre-emergents available to homeowners around ornamental plantings and in vegetable gardens, but always read the label! The label instructions will also tell you if you can use the pre-emergent on newly seeded or sod lawns, and how long to wait before mowing.

Using a post-emergent, selective herbicide
You didn’t get your pre-emergent down in time and crabgrass is invading your lawn? Consider using a post-emergent, selective herbicide such as 2,4-D (Weed-B-Gon, All-In-One, and other brands). Spray directly on the crabgrass weed, just to the point of runoff, rather than broadcasting. A rain-free day when your lawn has not been recently mowed is best. Again, be sure to read the label.

Mechanical control
For ongoing crabgrass management, I like to simply hand-pull. A weekly walk over my lawn with my handy weed-digger tool, and an eagle-eye to spot emerging leaves, keeps crabgrass and other lawn weeds in check—and I appreciate the exercise bonus!

Chemicals and manual labor aside, a thick, healthy lawn, that denies weed seed from coming in contact with the soil and getting adequate light for germination, is the best defense against crabgrass.

Article written by Beth Leonard, Extension Master Gardener Volunteer.

 Resources
http://www.turffiles.ncsu.edu/alerts/weeds/preemergent-herbicides-for-summer-annual-weed-control-in-turfgrass

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Buncombe County Extension Office
49 Mount Carmel Road
Asheville, NC 28806
Helpline 828-255-5522

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