• Blog
    • General Gardening
    • Gardening for Children
    • Gardening Videos
    • Insect Pests
    • Landscape Design
    • Trees
    • Vegetables & Fruits
    • Weeds
  • Events
    • Upcoming Events
    • Event Announcements
  • Gardening Videos
  • Resources
    • Western North Carolina Gardening Guide
    • Online Resources
      • Soil Testing Information for Home Gardeners
    • Speakers Bureau
  • Garden Helpline
    • Collecting Samples of Plants and Insects
  • The Learning Garden
  • About Us
    • About Us
      • How to Become an Extension Master GardenerSM Volunteer
    • The Association
    • Contact Us
    • Speakers Bureau
    • Sponsors
      • Sponsors: 2019 WNC Gardening Symposium
    • Donate
Extension Master GardenerSM Volunteers of Buncombe County

pest control

Two Insects to Watch for on your Rhododendrons

May 19, 2014

Probably the first insect of the season to show up on your Rhodos will be the Black Vine Weevil…so-called because grape vines are among the various plants on which it’s found.   The adult is a small, 3/8″, black beetle that emerges in late spring.  They feed at night, chewing on the edges of the leaves and dropping to hide in the litter below during the day. 

courtesy of the University of Maine
courtesy of the University of Maine
the CULPRIT...courtesy of the University of Maine
the CULPRIT…courtesy of the University of Maine

You want to distinguish between damage that occurred last year and that caused by the current generation.  If you’re into nocturnal adventure, in late May start scouting for them with a flashlight after dark. Look for those notches  particularly,  on the lower leaves. Or, you could lay sheets of cardboard beneath the shrubs and check under the sheets for the beetles’ presence during the day. 

Unfortunately the vine weevil larva, small white grubs with brown heads, will soon be feeding on the plants’ roots, limiting their ability to take up moisture or nutrients. Your rhodos may be getting a double whammy and that would show up as chlorotic, yellowing, leaves.

If you do identify the black vine beetle as the culprit, Beauveria bassiana, a naturally-occurring fungus that causes a disease in the insect, is registered for its control. Read the label to see how to apply.

The presence of the Rhododendron borer will be signaled by the wilting, curling and eventual dying of the leaves, so by that time you see it, it’s too late to mount an effective attack. The objective is to catch the culprit before they can do significant damage and that means checking below the branches looking for frass or sawdust expelled by the insect as it bores his, or hers, entry hole.  The frass signals that the Borer is inside the stem above that point working its way downward. Identify the branch by locating the small, quarter-inch entry hole.

courtesy of University of Maryland
courtesy of University of Maryland

Now how far down has the critter gotten?  We can determine by cutting off successively lower parts of that branch until we find a section with no hole bored in the center.  The borer hasn’t gotten that far so now remove all of that branch down to where it joins the next stem.  Make a clean cut so that it will heal quickly. Dispose of the pieces removed.  Bury them, trash them, somehow get them out of the garden.

Rhodo Borer2

Article written by Glenn Palmer, Extension Master Gardener Volunteer.

Share this:

  • Click to share on Facebook (Opens in new window)
  • Click to share on Pinterest (Opens in new window)
  • Click to share on Twitter (Opens in new window)
  • Click to share on Pocket (Opens in new window)
  • Click to email a link to a friend (Opens in new window)

Categories Insect Pests, Shrubs Tags black vine weevil, borer, pest control, rhododendron

Japanese Beetles

February 24, 2013

beetle adultFirst reported in North America in 1916, the Japanese beetle now occurs in most of the eastern United States. About 1/2 inch long, Japanese beetles are a shiny, metallic green with coppery brown wing covers that extend almost to the tip of the abdomen. Small tufts of white hairs occur at the tip of the abdomen and along each side. Eggs are translucent white to cream and elliptical and about 1/16 inch in diameter when first laid. In a few days, the egg becomes more spherical and doubles in size. Grubs are white, slightly curled and have yellow-brown heads. Grubs are about 1 inch long when mature. Unlike other grubs found in turf, it has two rows of spines which form a “V” on the underside of the last abdominal segment. The pupa is approximately 1/2 inch long and 1/4 inch wide, and it gradually turns light brown and then develops a metallic green cast.

Biologygrub
Adult Japanese beetles sometimes emerge as early as mid May in eastern North Carolina. Peak emergence occurs mid-late June in most areas and lasts a few weeks. The beetles attack the foliage, flowers and fruit of many plants. Japanese beetles feed on over 275 different kinds of shade and fruit trees, shrubs, flowers, small fruits, garden crops, and weeds. Some of their favorites are roses, crape myrtle, linden, grapes, as well as ornamental and other fruit trees. They typically feed on the upper leaf surface eating tissue between leaf veins giving leaves a lacy appearance. Beetles will generally consume entire petals of roses and other flowers.

Japanese beetles aggregate in response to odor released by damaged plants and a pheromone released by female beetles. This aggregation and mass feeding can result in severe defoliation of plants.

Soon after emerging, female beetles burrow 2 to 3 inches into damp soil and deposit 40 to 60 eggs in small batches. During dry periods, adults may be more attracted to low lying and irrigated areas to lay eggs where soil moisture is higher. In extremely dry weather, many eggs and larvae perish. In warm, wet summers, eggs hatch in about 2 weeks. The newly emerged larvae feed until cold weather forces them into hibernation. One generation occurs each year.

The beetle grubs are only occasional pests of the roots of grasses and shrubs. Japanese beetle grubs occur in lawns, golf courses, pastures and even wooded areas. They burrow through the soil feeding on roots. Areas of dead grass may appear when large numbers of grubs are present especially during dry spells in September or early October. The grubs overwinter in cells about 6 inches deep. In spring, they move almost to ground level, where they complete feeding and then pupate. Japanese beetle grubs rarely do enough damage in a home lawn to warrent treatment. The threshold is approximately 12+ grubs per square foot.

Scouting/Monitoring
Japanese beetles adults generally become active in late May or early June in North Carolina depending on location and weather. Peak abundance and feeding occurs in late June or early July. Monitoring can easily be done with commercially available bag-type Japanese beetle traps. You can also monitor highly attractive plant species such as roses for the appearance of beetles. Traps are commercially available. The traps are much more effective in attracting Japanese beetles than in trapping them. Consequently, traps should be placed as far away from the plants to be protected as possible. If traps are used, place far away from susceptible plants. Traps, alone, are not likely to give satisfactory protection to plants being eaten by adult Japanese beetles and pesticides may be required, anyway.

Decision Making
Deciding when and how to manage Japanese beetles will depend on beetle activity in your area and the value and vulnerability of plants on your property. A number of plant species and varieties are unlikely to be attacked or heavily damaged by Japanese beetles and thus would not require intervention. However, highly susceptible plant species such as roses could suffer severe damage and warrant some sort of intervention.

Commercial nursery and landscape operators will have less tolerance for damage in order to keep plants salable and presentable in the landscape. Commercial operators should reference Insect Note xx “Management of Adult Japanese Beetles for Commercial Nursery and Landscape Operations” for more information.

Intervention/Control
Flowers and ornamental plants can be protected by dusting or spraying foliage with pesticide. However, there are a number of options for reducing damage to landscape plants that do not rely entirely on pesticide applications. Many plants are not significantly bothered by Japanese beetles. There are also varieties of their favorites that are less preferred than others. For a list of susceptibility of certain woody ornamentals to Japanese beetle damage see the Mississippi State study.

Homeowners can take advantage of the beetles’ aggregation behavior by shaking plants to dislodge beetles each morning. Without beetles already on a plant, it is less likely that beetles will aggregate there later in the day. Picking beetles off by hand will also reduce the accumulation of beetles that results in severe damage. They can be easily knocked into a widemouth jar of soapy water. In some settings, flowers or plants can be protected with cheesecloth or other fine mesh.

If insecticides are desired to protect plants in the landscape, there are a number of products available. For home use, carbaryl (Sevin), malathion, imidacloprid (Merit) are good choices. Many of the newer lawn and garden multi-insect products containing one of the pyrethrins are also effective. Pyrethrin containing chemicals are slightly more persistant. Sevin will protect foliage for about five days, weather permitting, so it would have to be reapplied. Pyrethroid based products may give up to two weeks of foliar protection per application. Spinosad and Neem based products are less effective, but are preferred by some gardeners seeking “softer” chemicals. Homemade concoctions and blended beetle cocktail repellants are slightly effective at best, and may need reapplication every one or two days.

Japanese beetle traps may catch up to 75% of the beetles that approach them. However, they are not control devices. Traps may lower beetle populations slightly, but only if placed throughout an entire neighborhood at very high density. This will not be enough to significantly reduce damage on your prized garden foliage. The trapped beetles must be emptied from the traps every one to two days to prevent them from rotting and releasing ammonia which is repellant to other Japanese beetles. The traps are much more effective in attracting Japanese beetles than in trapping them. Consequently, traps should be placed as far away from the plants to be protected as possible. If traps are used, place far away from susceptible plants. Traps, alone, are not likely to give satisfactory protection to plants being eaten by adult Japanese beetles and pesticides may be required, anyway.

For commercial operations, a number of systemic products such as imidacloprid are effective and protect trees for longer periods of time. Commercial operators should reference Insect Note 147 “Management of Adult Japanese Beetles for Commercial Nursery and Landscape Operations” for more information.

Grub control
Commercial soil treatment preparations of the Bacillus popilliae (milky spore disease) offer very little benefit. These spores infect and kill only Japanese beetle grubs. The spores are released into the soil and infect new grubs as they come in contact with the bacterial spores. Milky spore preparations can be applied from July until the first hard freeze to areas of turf grass that are mowed to 2 to 3 inches tall. These areas are preferred egg laying sites for adults and here, during the warm months, grubs feed close to the soil surface. Results of milky spore have been disappointing, however, and generally do not justify the expenditure. Milky spore treatment also provides little relief for the homeowner from the onslaught of foliage feeding by the highly mobile adults which fly into the area. Japanese beetle grub populations rarely reach economic threshold levels as turf pests in home lawns. A general threshold is 10 grubs per square foot (fewer on commercial turf) before turf damage becomes an issue. In addition, only small areas of the turf may be infested, so do not assume the entire area is infested. Heterorhabditis species of nematodes may be a more viable non-chemical alternative for turf protection, but application directions must be carefully followed. Remember, home lawns rarely need Japanese beetle grub intervention.

Soil insecticides for grub control are available, but rarely needed or justified for home owners. Imidacloprid-based insecticide applications any time from late spring through summer are fairly effective. The residual life of the soil applied chemicals varies, so follow the label instructions. Killing all grubs in a lawn will not protect your shrubs from Japanese beetle adult feeding so grub insecticides for adult beetle control are an unnecessary use of pesticide.

No matter which product or approach is selected, be sure to follow label directions. Recommendations for insecticides approved for control of these insects in home lawns can be found under the “White Grubs” listing in the Insect Control in Home Lawns section of the NC Agricultural Chemicals Manual. Recommendations for insecticides approved for use on sod farms, golf courses or other commercial sites can be found in the Commercial Turf Insect Control section of the NC Agricultural Chemicals Manual.

Useful References

  • APHIS Japanese Beetle Homeowners Manual
  • Minnesota note http://www.extension.umn.edu/distribution/horticulture/DG7664.html
  • Relative Susceptibility of Woody Landscape Plants to Japanese Beetle. David Held, Mississippi State University. Journal of Arboriculture 30(6) November 2004. http://www.treelink.org/joa/2004/nov/held11-04.pdf
  • Redmond, C. T. and D. A. Potter. 1995. Lack of efficacy of in vivo- and putatively in vitro-produced Bacillus popilliae against field populations of Japanese beetle grubs in Kentucky. J. Econ. Entomol. 88: 846-854.
  • Klein, M.G. 1992. Chapter 4. Use of Bacillus popilliae in Japanese Beetle Control, pp 179-190. In: Use of Pathogens in Scarab Pest Management. T.R. Glare & T.A. Jackson, eds., Intercept Ltd., Andover, England. 298pp.
  • White Grubs in Turf. NC Note http://www.ces.ncsu.edu/depts/ent/notes/O&T/lawn/note67/note67.html

Recommendations of specific chemicals are based upon information on the manufacturer’s label and performance in a limited number of trials. Because environmental conditions and methods of application by growers may vary widely, performance of the chemical will not always conform to the safety and pest control standards indicated by experimental data.

Recommendations for the use of chemicals are included in this publication as a convenience to the reader. The use of brand names and any mention or listing of commercial products or services in this publication does not imply endorsement by the North Carolina Cooperative Extension Service nor discrimination against similar products or services not mentioned. Individuals who use chemicals are responsible for ensuring that the intended use complies with current regulations and conforms to the product label. Be sure to obtain current information about usage and examine a current product label before applying any chemical.

Other Resources

  • Back to Insect Notes
  • Horticulture Information Leaflets(HILs)
  • Plant Disease Notes
  • North Carolina Agricultural Chemicals Manual
  • North Carolina Cooperative Extension Service

For assistance with a specific problem, contact your local North Carolina Cooperative Extension Service.

Article written by Patsy McNatt, Extension Master Gardener Volunteer.

Share this:

  • Click to share on Facebook (Opens in new window)
  • Click to share on Pinterest (Opens in new window)
  • Click to share on Twitter (Opens in new window)
  • Click to share on Pocket (Opens in new window)
  • Click to email a link to a friend (Opens in new window)

Categories Insect Pests Tags grubs, Japanese beetles, pest control

Want to Get Rid of Your Hemlock Woolly Adelgids?

February 5, 2013

Photo of Hemlock Wooly Adelgids on plant

The hemlock woolly adelgid is a difficult insect to control because the fluffy white secretion protects its eggs from pesticides. A good time to attempt control it is in October when the second generation begins to develop.

The insecticidal soap and the horticultural oil sprays seem to be very effective for adelgid control with minimal harm to natural predators and parasites of this pest. Trees that are heavily infested and are showing symptoms of decline should probably be sprayed. Horticultural spray oil can be applied during the winter and before new growth emerges in spring. Oil sprays may damage hemlock during the growing season, especially in dry weather.

Registered pesticides containing imidacloprid or dinotefuran may be useful for specimen trees located away from water sources. These insecticides are systemic and are often applied as soil injection. Dinotefuran may be applied as a trunk spray. Dinotefuran has a faster uptake, and imidacloprid has a longer residual protection. For additional pesticides, consult the North Carolina Agricultural Chemicals Manual, “Trees and Woody Ornamentals” Section, Adelgids.

Researchers with NCSU, in cooperation with the NC Dept. Agriculture and Consumer Services, are conducting biological control strategies using releases of a tiny Japanese lady beetle, Sasajiscymnus tsugae (formerly Pseudosymnus tsugae) in hopes of reducing the damage this pest causes to hemlocks. Scymnus sinuanodulus and Scymnus ningshanensis are two additional lady beetles recently introduced. Laricobius nigrinus, a native beetle from western North America is being tested. Similar programs in other states have shown good results.

Share this:

  • Click to share on Facebook (Opens in new window)
  • Click to share on Pinterest (Opens in new window)
  • Click to share on Twitter (Opens in new window)
  • Click to share on Pocket (Opens in new window)
  • Click to email a link to a friend (Opens in new window)

Categories Insect Pests, Trees Tags adelgids, hemlocks, pest control, woolly adelgid

  • « Previous Page
  • 1
  • 2
  • 3
  • 4

NC Cooperative Extension; Empowering People, Providing Solutions

Blog posts written and published by Extension Master GardenerSM volunteers in Buncombe County.

Subscribe via Email

Enter your email address to subscribe to our blog and receive notifications of new posts by email.

Join 3,716 other subscribers

Recent Posts

  • Saturday Seminar: Pruning Tools Workshop—Tool Selection and Sharpening, February 18
  • Online Seminar: Fruit Trees for Home Gardens February 16
  • Dramatic Winter Damage? What Should I Do?
  • What’s THAT Evergreen? Can I grow it?
  • A Gardening Guide for Our Mountains: The Perfect Holiday Stocking Stuffer

Categories

  • Events
    • Extension in Buncombe County
    • Extension Master Gardener Plant Clinic
    • Lectures & Seminars
    • Plant Sales
    • School Garden Grants
  • Flowers
    • Bulbs
    • Perennials & Biennials
    • Roses
    • Wildflowers
  • Gardening for Children
  • Gardening Videos
  • General Gardening
    • Installation & Planting
    • Mulch
    • Native Plants
    • Propagation
    • Seasonal Chores
    • Soils & Fertilizers
  • Houseplants
  • Landscaping
    • Firewise Landscaping
    • Landscape Design
    • Site Conditions
    • Water Management
  • Lawns
  • Pest Management
    • Integrated Pest Management (IPM)
    • Invasive Plants
    • Pesticides
    • Weeds
  • Plant Diseases
  • Plant Insects
    • Beneficial Insects
    • Insect Pests
    • Invasive Insects
  • Shrubs
  • Special Gardens
    • Container Gardens
    • Herb Gardens
    • Pollinator Gardens
    • Rain Gardens
    • Shade Gardens
  • Trees
  • Vegetables & Fruits
  • Wildlife

Contact Us

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

Events

Keep up with our events by subscribing to the blog or checking our Events Calendar.

Explore the Archives

Back to Top

Copyright © 2023 Extension Master Gardeners of Buncombe County. Privacy Policy.