Extension Master GardenerSM Volunteers of Buncombe County

Pest Management

Weeds Overwhelming? How to Cope!

Warm, wet weather equals a wealth of weeds. Despite many of us being home more of the time this summer, we can’t seem to keep up with the weeds! Fortunately, there are weed scientists who can help!

 

 

Weeds compete with your vegetable garden crops


Why care about weeds?
Maybe you are hoping to just peacefully coexist with your weeds, but according to Kira Sims, a Ph. D. candidate and graduate teaching and research assistant in the North Carolina State University Horticultural Science program, weeds:

  • Compete for resources—such, as nutrients, space and sunlight—with more desirable plants.
  • Can reduce crop yields.
  • Adversely affect human health—some weeds such as ragweed and poison ivy can cause allergic reactions.
  • Alter ecosystems—weeds can crowd out native plants or even make soil less hospitable to natives through altering pH, for example.

What can you do about weeds? IWM!
Integrated Weed Management is “Science-based, socially acceptable, environmentally responsible and economically practical crop protection against pests” says Sims, using all of the tools in your toolbox!

What’s in the toolbox?
Sims advocates the PAMS approach:

  • Prevention tools include:
    • Using clean (weed-free) compost, mulch, seeds, topsoil, transplants.
    • Don’t let weeds reproduce—by setting seed, suckering and so on.
    • Water desirable plants not weeds.
    • Clean equipment that might transport weeds
    • Remember you and your pets can transport weed seeds!
  • Avoidance tools include:
    • Clearly define where you want to exclude weeds
    • Help your desirable plants outcompete the weeds by:
    • Choosing appropriate plants
    • Plant at the correct time
    • Fertilize appropriately
    • Rotate crops
  • Monitoring tools:
    • Scout for weeds regularly
    • Keep records of crops and the weeds that cause problems
    • Test soil to determine appropriate fertilization
  • Suppression tools for when you can’t prevent or avoid all weeds:
    • Reduce tilling—which brings up weed seeds
    • Use narrow row spacing to shade out weeds
    • Use cover crops and/or mulch over bare soil
    • Manage irrigation

                                    

                                          Article by Buncombe County Extension Master GardenerSM Volunteers

For more information:

Weed publications from NCSU, including specific links on managing crabgrass, Japanese stiltgrass, and ragweed:

https://content.ces.ncsu.edu/catalog/?keywords=weed-management

 

 

 

 

 

Managing Garden Pests: Insecticidal Soap?

 

Insecticidal Soap example-No Product Endorsement is intended.

Do you prefer organic pest control? Have you seen lots of homemade pest remedies on Facebook or gardening websites that you wonder if you should try? Then you’ve probably heard of insecticidal soap! What you may not know is that:

  • Many things we think of as “soaps” aren’t really soaps
  • Not all soaps are effective as insect killers
  • Many soaps may damage or even kill your plants rather than your pests!

So what ARE insecticidal soaps?

Insecticidal soaps are soap products registered as insecticides. According to Raymond Cloyd, Extension Entomologist, Kansas State University, they are “‘reduced risk’ insecticides…used in certain situations because they leave minimal residues, are less toxic to humans, and are short-lived in the environment because they degrade rapidly.” He notes that “Soap is a general term for the salts of fatty acids.”

The Environmental Protection Agency only registers potassium salts of fatty acids as active ingredients of insecticidal soaps. Why does this matter? Other salts and other fatty acids in soaps aren’t necessarily effective as insecticides—and may be harmful to plants!

Should you use an insecticidal soap for pest control?

First, identify your pest! Not all insects are pests and not all pests are controlled with insecticidal soaps. Then decide if your plants will benefit from using insecticidal soap:

  • Will the affected plants tolerate insecticidal soap? Read the label to be sure the product is registered for use on the garden plants that pests are threatening.

  • Insecticidal soap label.
  • Do your plants need intervention—how much pest damage can you—and your plants—tolerate?

  • Adult Ladybug eating an aphid. Do you need an insecticide?

Commercially produced insecticidal soap sprays can effectively kill “soft-bodied” pests they come in contact with, such as:

  • Aphids,
  • Leafhoppers,
  • Mealybugs,
  • Mites,
  • Scales,
  • Thrips, and
  • Whiteflies
  • Thrip damage on onions. Is this sufficient to warrant use of an insecticide?

    Whiteflies: Does this infestation justify using an insecticide?

Insecticidal soaps are most effective on the early stages of pest development—such as larvae—and safest when applied only to plants listed on the product label when those plants are not under too much stress. In other words, use insecticidal soap when pests first start to appear in sufficient numbers to become a threat to your plants.

Ladybug larva eating aphids. Insecticidal soap will kill both the ladybug larva and the aphids.

Insecticidal soaps can’t:

  • Control soft-bodied insects after the spray dries on the plant—only spray when you can see the pests!
  • Control “hard-bodied” insects, such as beetles.
  • Distinguish between beneficial insects and pests!

Are all insecticidal soaps organic?

Check the Organic Materials Review Institute (OMRI) list for registered organic pesticides. Many pesticides that contain potassium salts of fatty acids contain other active ingredients that are not organic.

 What about those recipes for insecticidal soap?

Many “soaps” you have in your home are detergents, not soaps! These cleaning products may kill your plants rather than your pests. Even those soap products on your shelf that might have some insecticidal properties may damage your plants or may not be as effective as products registered for garden use. If asked, the makers of popular soap products will emphasize like we do—read the label! If the product isn’t registered for garden use, don’t use it!

Article by Buncombe County Extension Master GardenerSM Volunteers

For more information:

Raymond Cloyd, “Fundamentals of Using Soaps as Insecticides”:

https://blogs.k-state.edu/kansasbugs/2020/06/12/fundamentals-of-using-soaps-as-insecticides/

OMRI Products List: https://www.omri.org/omri-lists/download

How to choose a pesticide: http://npic.orst.edu/pest/select.html

Discussion of pest tolerance: https://extension.entm.purdue.edu/radicalbugs/default.php?page=decision_making

Organic gardening: https://content.ces.ncsu.edu/extension-gardener-handbook/17-organic-gardening#insects

 

 

Non-Native Invasive Plants: Japanese Spirea

Japanese Spirea

What is Japanese spirea?
Gardeners imported Japanese spirea (Spiraea japonica) to the United States in 1870 for use in Victorian-era landscapes. The easy-to-grow shrubs with the compact habit and pink flowers remained a favorite. Now Japanese spirea is one of many Asian shrubs threatening the ecosystems of our native southern forests.

Why is it a problem?
Japanese spirea has small seeds that wash away and rapidly take over disturbed areas; they are especially a problem when they reach stream banks. Seeds may also arrive in fill dirt used in home construction.

Once established, Japanese spirea forms dense stands that outcompete the native forest flora. Seeds from Japanese spirea can last for years in the soil, making the spread difficult to control. Note that although Japanese spirea is not yet on North Carolina’s statewide list of invasive plant species, it is specifically noted as an invasive plant in Buncombe County and the Great Smoky Mountains National Park.

Some cultivars of the invasive Japanese spirea have golden leaves like this ‘Goldflame’ spirea

How Can I Help?
Don’t plant Japanese spirea! Consider using native plants in your landscape. Some alternatives are:
• The native spireas, white meadowsweet (Spiraea alba),

The native meadowsweet has white flowers.

• sweet pepperbush (Clethra alnifolia),
• silky dogwood (Cornus amomum),
• leatherleaf (Dirca palustris),
• Virginia sweetspire (Itea virginica),
• ninebark (Physocarpus opulifolius).

This native clethra has pink flowers.

Consider removing existing plants.
If you can’t easily dig up your planting, cutting back and repeated mowing can help eliminate unwanted shrubs. Be sure to keep cutting back to prevent seed production!
For large infestations, herbicides containing triclopyr or glyphosate are effective. Be careful to follow label directions!

Article by Barbara Hayes, Extension Master GardenerSM Volunteer

For more information:
Weed of the Week:https://www.invasive.org/weedcd/pdfs/wow/japanese-spiraea.pdf

Distribution of Japanese spirea:https://www.invasiveplantatlas.org/subject.html?sub=3076

Invasive exotic plants in the Great Smoky Mountains National Park:https://www.nps.gov/grsm/learn/nature/non-natives.htm

Contact Us

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

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