Extension Master GardenerSM Volunteers of Buncombe County

insects

Galls in Your Garden? What to do!

Horned Oak Gall

Is there something weird growing in your landscape? I recently spotted this horned oak gall and knew I needed to find out what it was! Galls are something gardeners often notice—usually with alarm. What are they and do you need to do anything about them?

What are galls?
Unusual plant growths are often—but not always—galls.

  • Causes for gall growth include:
    • Critters—from adelgids and aphids to beetles, midges, mites, sawflies, and wasps
    • Bacteria and fungi
  • They affect many plants:
      • Trees
      • Shrubs
      • Perennials
  • And many plant parts:
    • Buds, flowers, and fruit
    • Leaves
    • Stems, twigs and branches
    • And even roots!
  • Galls may appear in different seasons, as well as change across seasons.
    • Azalea leaf gall - three stages of development. Photo by James H. Blake, courtesy of Clemson University Extension.
      Azalea leaf gall – three stages of development. Photo by James H. Blake, courtesy of Clemson University Extension.

      This spring you may have seen signs of azalea/camellia leaf galls (caused by Exobasidiumvaccinii/
      Exobasidium camelliae fungi) or maple eyespot galls (caused by Acericecis ocellaris midges) on your maple tree leaves.

    • Come summer you may have seen signs of crown gall (caused by soil bacterium Agrobacterium tumefaciens) on your roses, or oak apple galls (caused by wasps Amphibolips confluenta or quercusinanis) on your oaks.
    • As summer progresses, you may see evidence of life stages of horned oak galls (caused by Callirhytis cornigera wasps).
Horned Oak Gall leaf gall stage
    • Come fall and winter, goldenrod galls (caused by Eurosta solidagnis flies) are easy to spot.

 Which need attention?
It depends!

Aesthetics. Although galls may be fascinating, if you find them unsightly, you may want to remove them even if they will do no lasting harm to your plants.

Pros:

  • Removal may improve your plant’s appearance
  • Cleanup may help prevent further damage or disease.

Cons:

  • Removal may be impossible—think leaf galls that affect many leaves, such as Witch hazel cone galls.
  • Cleanup may remove the benefits to wildlife of some galls—birds feed on the larvae in goldenrod galls; birds, and some mammals, feast on the wasp larvae in oak apple galls.

Plant decline. Some galls left untreated will harm plants and may eventually kill them! Do not ignore Azalea/Camellia galls, crown galls, and horned oak galls.

What to do?

Prevention. When bacteria cause galls—crown galls, for example—there must be an opening to cause an infection. Careful handling to avoid wounding your plants as well as removing insect damage can help. Take care to clean and sanitize tools that might spread infection. Sanitation is also important for preventing fungal galls, such as Azalea/Camellia galls—dispose of diseased tissue in the trash, as well as clean any tools used.

Pruning is the answer to many aesthetic as well as more serious problems. Removing affected leaves or other plant parts may be all that is needed. In other cases, it may help, but it isn’t a cure-all. In the case of bacterial disease, for example, the cause of the gall is systemic and may or may not have a cure. Removal of early stages of horned oak gall wasp infestation can save trees.

Article by Buncombe County Extension Master GardenerSM Volunteers

 For more information:

Azalea/Camellia leaf galls: https://www.buncombemastergardener.org/time-maintain-remove-leaf-gall-azaleas-camellias/

Bacterial crown gall: https://extension.umd.edu/resource/bacterial-crown-gall-flowers

Horned oak gall wasp:

https://bygl.osu.edu/node/1019

http://joa.isa-arbor.com/request.asp?JournalID=1&ArticleID=2922&Type=2

Goldenrod gall fly:

https://hort.extension.wisc.edu/articles/goldenrod-gall-fly-eurosta-solidagnis/

Maple eyespot gall: https://content.ces.ncsu.edu/maple-eyespot-gall-midge-acericecis-ocellaris-osten-sacken-diptera-cecidomyiidae

Oak apple gall: https://bygl.osu.edu/node/344

Sampling of gall photos:

https://projects.ncsu.edu/cals/course/ent525/close/gallpix/

https://www.maine.gov/dacf/php/gotpests/diseases/galls.htm

Series of American Nurseryman articles on galls:

https://www.amerinursery.com/plants/plant-galls-myths-misconceptions/

https://www.amerinursery.com/pest-management/insect-and-mite-galls-myths-and-misconceptions/

https://www.amerinursery.com/american-nurseryman/managing-galls/

 

Kids Post: Good bugs!

Do you like bugs? Getting to know bugs can be a fun—and important—part of enjoying gardening. There are almost 1,000 different types of bugs that live in North Carolina—most of them won’t damage our gardens, and some actually help us!

What ARE bugs?
• Scientists call them “arthropods.”

From “Good Bugs and Bad Bugs”

• Most are insects with 6 legs and 3 main body parts: a head, a thorax, and an abdomen.

From “University of Kentucky, Spider Anatomy”

• Spiders and daddylonglegs are not insects—they are part of a special group of arthropods called “arachnids.” They have 8 legs and 2 main body parts: a cephalothorax and an abdomen.

Daddylonglegs are arachnids that prey on insects, but don’t spin webs like spiders.

What makes good bugs good?

• They live off of bad bugs!

Wheel bug preying on a bee. Sometimes good bugs eat any bug they can find.

o Some prey on insects: lady beetles (you may call them lady bugs), wheel bugs, soldier bugs, and spiders may eat other insects—young and adult—as well as their eggs.

Braconid wasp eggs laid on tomato hornworm.

o Some parasitize insects: braconid wasps, for example, lay their eggs on tomato hornworms so the new hatchlings will have a meal waiting for them!

Black Swallowtail_John Flannery_CC BY-ND 2.0_Flickr
Black swallowtail pollinating a zinnia flower.

• They pollinate plants: bees, butterflies, and moths that feed on pollen and/or nectar move pollen from flower to flower, helping pollinate plants.
Where to look for bugs:
• You can find bugs on many garden plants. IMPORTANT: look, but don’t touch! Many bugs can bite (such as wheel bugs) or sting—even touching the “hair” on some caterpillars can hurt! Also, you may injure or kill a helpful bug if you try to catch it!

• Look for insect eggs, young (larvae), and adults:

o On branches

Lady beetle laying eggs on branch.

o On flowers


o On the leaves—look underneath the leaves, too!

Wheel bug larva.
Green lynx spider feeding on wasp.

o In the soil
Identifying bugs:
• One place to start is to have an adult help you look on the internet: For example,https://www.insectidentification.org/bugfinder-start.asp is a page that shows the shape of each type of bug and then helps you decide if the bug you’ve seen is that type of insect or arachnid.
• Identify our native bees here: https://content.ces.ncsu.edu/the-bees-of-north-carolina-identification-guide
Protecting good bugs:
If you want good bugs that help control bad bugs in your garden, you need to let them be and be careful about using pesticides!
Make sure that your plants are healthy—plant them in the right amount of sunlight and give them the right amount of water and fertilizer—and that you have some native plants in your garden; healthy plants make good homes for good bugs.

Learning more:
“Lady bugs” for kids: https://www.clemson.edu/public/scbg/education/ladybug1.pdf

Beneficial insects:https://growingsmallfarms.ces.ncsu.edu/growingsmallfarms-beneficials/

North Carolina insects:https://www.insectidentification.org/insects-by-state.asp?thisState=North%20Carolina

Insect identification:https://bugguide.net/node/view/15740

Bug facts site:https://www.bugfacts.net/

Has a printable bug checklist:https://www.bugfacts.net/images/checklist-z.pdf

Where to find bugs:http://www.bugpeople.org/pubs/pdf/10SurePlaces.pdf

EMG Blog: https://www.buncombemastergardener.org/beneficial-insects-attracting-good-voracious-ugly-garden/

Good Bugs and Bad Bugs: Student Booklet: http://entomology.tamu.edu/wp-content/uploads/2017/10/Good_Bugs.pdf

Spider Anatomy: https://www.uky.edu/Ag/CritterFiles/casefile/spiders/anatomy/spideranatomy.htm#palps

Pest Alert: Nantucket Pine Tip Moth

If you’re spending more time outside as the weather warms, you might notice problems in your landscape. One homeowner called the Garden Helpline about white webbing on the ends of some of the branches of a tree purchased as a live Christmas tree. She planted the tree in a special place in her yard as a reminder of that happy occasion. Although she knew it was a pine, diagnosing the problem required determining what pine species it was. The number of needles in each needle bundle can identify pine species. She reported that there were 3 needles in each bundle, helping identify the tree as a Scotch pine (Pinus sylvestris), a very popular Christmas tree species.

Scotch PIne three needle bundle
Three needle bundle pine

Damage: The description of the webbing she saw helped determine that her tree was infested with the Nantucket pine tip moth, (Rhyacionia frustrana). Other signs include:

• Deformed growth (stem crooking) or a reduction in growth (bushy or stunted growth);
• Fecal deposits may be present in the webbing on the outside of infested shoots;
• Trees can be killed when exposed to repeated Nantucket pine tip moth larval infestations.

Damage caused by Nantucket Pine Tip Moth

Identification:

• In North Carolina, this pest overwinters as pupae in hollowed out pine shoots;
• On warm days as early as January and February, new moths emerge to mate;
• Adult moths are 1/4 inches (6.3 mm) long with the head and body covered with gray scales. The forewings are covered with brick-red to copper-colored patches that are separated by irregular bands of gray and white scales;
• Adult females lay white to opaque eggs on shoots, needles, or terminal growth in spring;

Adult Nantucket Pine Tip Moth

• From 5 to 30 days later, young larvae (caterpillars) hatch from eggs and feed on the surface of new growth. These are 1/16 inches (1.6 mm) long, and cream-colored with a black head. They then move to the shoot tips, construct protective webs at the base of buds, and begin to bore into the bud or stem.
• Feeding continues inside the bud or stem until the caterpillars are fully grown in 3 to 4 weeks. The caterpillars then pupate inside the damaged stem.

Management:

• Proper watering, fertilization, and mulching practices to keep pine trees healthy;
• For minor infestations, you can hand prune infested shoots if branches are reachable.

Susceptible pine species:

• Other three needle bundle pines, which include pitch pine (P. rigida) and loblolly pine (P. taeda).
• Two needle bundle pines are highly susceptible to infestation. These include Japanese red pine (P. densifolia), mountain pine (P. mugo) and Japanese black ine (P. thunbergii).

Resistant pine species:

  • Eastern white pine (P. strobus) and Virginia pine (P. virginiana), which have five needle bundles.

                                        Article by Bob Wardwell, Extension Master Gardener Volunteer

For more Information:
Nantucket Pine Tip Moth: https://content.ces.ncsu.edu/nantucket-pine-tip-mo

How to Identify Pines: https://smallfarms.cornell.edu/2019/02/arent-they-all-just-pines-how-to-id-conifer-trees/

Contact Us

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

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