Category Archives: Pest Alerts

Lily Leaf Beetle – Pest Alert

The lily leaf beetle (LLB), Lilioceris lilii, also known as the red or scarlet lily beetle, is an invasive insect of Eurasian origin.  This insect was first reported in North America in eastern Canada during World War II and was most likely introduced in shipments of plant materials from Europe.  LLB spread to New England in the 1990’s and has been moving westward since that time.  LLB made its first appearance in Wisconsin in 2014 and as of early 2021 has been found in 21 counties including Brown, Calumet, Clark, Dane, Door, Langlade, Lincoln, Marathon, Milwaukee, Oneida, Outagamie, Pierce, Portage, Price, Shawano, Taylor, Vernon, Vilas, Waukesha, Waupaca and Wood Counties.

Severe feeding damage from lily leaf beetles on a lily plant (left) and an adult lily leaf beetle (right). Photos courtesy of Leslie J. Mehrhoff, University of Connecticut, Bugwood.org
Severe feeding damage from lily leaf beetles on a lily plant (left) and an adult lily leaf beetle (right). Photos courtesy of Leslie J. Mehrhoff, University of Connecticut, Bugwood.org

LLB can cause significant damage to true lilies (Lilium spp.), including both native and cultivated types, as well as fritllaries (Fritillaria spp.).  LLB can also cause damage, but to a lesser extent, to lily of the valley (Convallaria majalis) and Solomon’s seal (Polygonatum spp.).  LLB does not cause damage to daylilies (Hemerocallis spp.), canna lilies (Canna spp.) or calla lilies (Calla palustris).

Appearance:  LLB adults are bright red and approximately 1/4 inch long, with black legs, head, antennae, and undersides.  When disturbed, LLBs tumble from plants and land upside down on the ground, where they play dead.  Their dark-colored undersides make them hard to spot.  To potentially deter predators, adults squeak if squeezed.

LLB larvae have plump, squishy bodies and are slug-like in appearance.  They tend to be orange or yellowish in color with black heads.  At maturity, larvae can be almost 1/2 inch long.  As a defensive tactic, larvae typically camouflage themselves with their own excrement and can resemble slimy greenish-brown slugs or a mobile pile of animal droppings.

LLB eggs are tiny (less than 1/10 inch long) and reddish in color.  Female LLBs lay the eggs (typically in a batch of a dozen or less) on the underside of leaves in a row parallel to a vein.

Symptoms and Effects:  Both LLB adults and larvae chew irregular holes and notches in lily leaves, stems, and developing buds.  Larvae are the more damaging stage of the insect.  When feeding damage is severe, LLBs can completely defoliate plants and destroy flowers.

Life Cycle:  There is a single generation of LLBs each year, but adults can live for several years.  LLBs overwinter as adults in sheltered places, soil, and plant debris in gardens and wooded areas.

These overwintering sites are not necessarily near lilies or other host plants.  Early in the spring, LLB adults emerge to feed, mate and lay eggs.  Because they are strong fliers, LLBs can disperse over long distances to locate host plants.  Eventually, females lay between 250 and 450 eggs.  Eggs hatch within four to eight days.  Emerging larvae feed for two to three weeks during the spring and early summer.  Engorged larvae eventually drop to the soil to pupate (i.e., transform into adults).  Pupae are bright orange and encased in a white cocoon with black spots.  Adults emerge 16 to 22 days later and feed throughout the rest of the growing season and into the fall.

Lily leaf beetle eggs (left) and a lily leaf beetle larva camouflaged with its own feces. Photos courtesy of Gail Hampshire (left) and Kenneth R. Law, USDA APHIS PPQ, Bugwood.org
Lily leaf beetle eggs (left) and a lily leaf beetle larva camouflaged with its own feces. Photos courtesy of Gail Hampshire (left) and Kenneth R. Law, USDA APHIS PPQ, Bugwood.org

Control:  If you have a small number of lilies, consider hand-picking and crushing adults and larvae or knocking them into a container of soapy water.  Also, crush eggs by hand if you see them.  Repeat this process regularly throughout the growing season.  If LLB becomes a chronic and severe problem, consider replacing your lilies with plants that are not attacked by the insect.

You can also use conventional and organic insecticides to help protect plants from the LLB.  Conventional insecticides containing carbaryl, cyfluthrin, cypermethrin, deltamethrin, lambda-cyhalothrin, permethrin, and zeta-cypermethrin control a broad range of pests, including LLB.  Organic insecticides containing azadirachtin, pyrethrins, or spinosad can also be used, as well as horticultural oils and insecticidal soap.  Make sure that the product that you select is labelled for use on landscape flowers.  Be aware that conventional and organic insecticides can pose risks to pollinators, so follow all directions on the label to minimize risks to bees and other pollinators.

For more information on lily leaf beetle:  Contact your county Extension agent.

Homeowner Guide to Emerald Ash Borer Insecticide Treatments – Pest Alert

Emerald ash borer insecticide treatment considerations.  Several insecticide products are available to homeowners for control of emerald ash borer (EAB).  Since the presence and infestation level of EAB is quite difficult to determine at early stages of an infestation, insecticide treatments may be merited to mitigate damage by EAB.  However, not all ash trees should be treated as some may be too extensively compromised or in poor condition to receive treatment.  Tree location, value, and health, as well as the cost of treatment are all factors to consider.  Due to the expense of yearly insecticide treatments, one should consider the value of a particular ash tree in relation to insecticide treatment costs before making any treatments.  In addition, consider the health of each tree before treating.  Research suggests that insecticide treatments are significantly more effective on EAB-infested ash trees with less than 50% canopy thinning.  Insecticide treatments are not suggested for trees with greater than 50% canopy thinning.  Trees with greater than 50% canopy thinning should be removed and handled in accordance with local guidelines.  For a more detailed discussion on this topic, see University of Wisconsin Garden Facts XHT1215, Is My Ash Tree Worth Treating for Emerald Ash Borer.

Emerald ash borer insecticide treatment options.  Insecticide products available for use by homeowners are summarized in Table 1.  They include:

  • ACECAP 97 Systemic Insecticide Tree Implants (acephate)
  • BioAdvanced 12 Month Tree and Shrub Insect Control (imidacloprid)
  • BioAdvanced 12 Month Tree and Shrub Protect & Feed (imidacloprid)
  • BioAdvanced 12 Month Tree and Shrub Protect & Feed II (imidacloprid + clothianidin)
  • Bonide Annual Tree & Shrub Insect Control with SYSTEMAXX (imidacloprid)
  • Compare N Save Systemic Tree & Shrub Insect Drench (imidacloprid)
  • Ferti-lome Tree and Shrub Systemic Drench (imidacloprid)
  • Monterey Once a Year Insect Control II (imidacloprid)
  • Several other products containing imidacloprid are also currently available

Most of the products available to homeowners are systemic insecticides containing imidacloprid and are applied as soil drenches around the base of an ash tree.  A few granular products are also available.  Recent university research suggests that applications of imidacloprid should be made in spring to be most effective.  Research also has demonstrated that soil applications of imidacloprid-containing homeowner products provide excellent EAB protection for ash trees that are less than about 47 inches in circumference [i.e., 15 inches in diameter at breast height (DBH)].  Due to differences in application rates and label restrictions, treatment by a tree care professional (e.g., arborist) may be the best option for larger trees.  For best results, treatment of trees should begin before trees become infested.  Lastly, insecticide treatments must be repeated each year to maintain the health of ash trees.

Be aware that many insecticide products available at hardware stores and garden centers look alike.  Carefully check all product labels before purchase to make sure that you have selected the correct product/active ingredient.  ALWAYS read and follow the pesticide label directions on the product that you select!

Finally, note that although ACECAP 97 Systemic Insecticide Tree Implants are available to homeowners, we do NOT recommend that homeowners use these because they require physically drilling into a tree during their application.

Table 1

Emerald ash borer insecticide treatments available to homeowners

Product Active Ingredient Timing Type of application
BioAdvanced 12 Month Tree & Shrub Insect Control (D)

BioAdvanced 12 Month Tree & Shrub Protect & Feed (D or G)

Bonide Annual Tree & Shrub Insect Control with SYSTEMAXX (D)

Compare N Save Systemic Tree & Shrub Systemic Insect Drench (D)

Ferti-lome Tree & Shrub Systemic Drench (D)

Monterey Once a Year Insect Control II (D)

Imidacloprid Mid-April to mid-May Soil Drench (D)

or

Granular (G)

BioAdvanced 12 Month Tree & Shrub Protect & Feed II (D or G) Imidacloprid

+

Clothianidin

Mid-April to mid-May Soil Drench (D) or Granular (G)
ACECAP 97 Systemic Insecticide Tree Implants Acephate Mid-May to mid-June Trunk Implant

Other emerald ash borer treatment options.  Homeowners may also contact a certified arborist or certified pesticide applicator to treat their trees.  See http://www.waa-isa.org for a list of certified arborists in Wisconsin.  Professionals have access to some products that are not available to homeowners.

The University of Wisconsin does not endorse commercially available insecticide products over those available directly to homeowners.  Products discussed in this fact sheet have been evaluated in university research tests on EAB.

For more information on controlling emerald ash borer:   See: https://eab.russell.wisc.edu, http://www.emeraldashborer.wi.gov or http://www.emeraldashborer.info or contact your county Extension agent.

Viburnum Leaf Beetle – Pest Alert

The viburnum leaf beetle (VLB), Pyrrhalta viburni, is an invasive insect that feeds exclusively on and can significantly damage Viburnum species.  VLB is native to Europe and was detected in Canada in 1947.  The first report of VLB in the United States was in New York State in 1996.  VLB is now found scattered across much of the northeastern US.  In Wisconsin, an isolated infestation of VLB was discovered in Dane County in 2009, but was successfully eradicated.  In 2014, VLB was detected on a mature viburnum bush in northern Milwaukee County and other nearby infestations were detected in June 2015.  As of early 2021, VLB infestations have been found in 12 Wisconsin counties, including Brown, Dane, Iron, Kenosha, Milwaukee, Ozaukee, Racine, Sheboygan Walworth, Washington, Waukesha, and Winnebago Counties.

Viburnum leaf beetles adults (left) and larvae (right). (Photos courtesy of Paul Weston, Cornell University, Bugwood.org)

Appearance:  Adult VLB’s are approximately ¼ inch long and yellowish-brown in color.  VLB larvae can be up to ⅓ inch long and range in color from yellowish-green to light brown with a series of black spots and dashes on their bodies.

Symptoms and Effects:  VLB larvae chew holes in viburnum leaves in the spring creating a lace-like (i.e., skeletonized) pattern.  VLB larvae feed individually or in small groups and can cause significant damage to viburnum shrubs.  This damage can resemble the feeding damage of Japanese beetles (see University of Wisconsin Garden Facts XHT1062 “Japanese Beetle”).  In late June and early July, VLB adults begin to feed, chewing oblong holes in leaves.  Severe VLB infestations can cause complete defoliation of a viburnum shrub, which weakens the plant over time and can eventually lead to death.

Life Cycle:  There is only one generation of VLB per year.  VLB’s overwinter as eggs and development from eggs to adults takes approximately eight weeks.  Larvae typically appear in early to mid-May and feed for several weeks, passing through three stages (instars) as they grow.  In early to mid-June, larvae pupate in the soil and adults emerge by late June or early July.  VLB females lay eggs during the summer and into October.  They chew small pits in twigs, deposit five to eight eggs into each pit, and then cover the pits with tiny pieces of chewed wood to protect the eggs.  Each female can deposit up to 500 eggs.  Eggs remain in place through the winter until they hatch the following spring.

Control:

Cultural:  When selecting viburnum plants for the landscape, DO NOT use arrowwood viburnum (Viburnum dentatum), European cranberrybush viburnum (Viburnum opulus), or American cranberrybush viburnum (Viburnum opulus var. americanum) as these types of viburnums are strongly preferred by VLB.  Instead use resistant viburnums such as doublefile viburnum (Viburnum plicatum f. tomentosum), Judd viburnum (Viburnum x juddii), or Koreanspice viburnum (Viburnum carlesii).  In addition, between October and the following spring, examine viburnums for twigs where VLB’s have laid their eggs.  Prune and destroy these twigs to reduce VLB numbers.  During the growing season encourage natural VLB predators in your area (e.g., lady beetles, spined soldier bugs, assassin bugs, green lacewings) that can reduce VLB numbers.

Adult viburnum leaf beetle feeding damage (left) and egg-laying sites (right). (Photos courtesy of Paul Weston, Cornell University, and Bruce Watt, University of Maine; Bugwood.org)
Adult viburnum leaf beetle feeding damage (left) and egg-laying sites (right). (Photos courtesy of Paul Weston, Cornell University, and Bruce Watt, University of Maine; Bugwood.org)

Chemical:  Prior to bud break, apply horticultural oil to twigs where VLB eggs have been laid.  This will significantly reduce the number of eggs that will hatch.  Control any surviving larvae with contact insecticides such as acephate, bifenthrin, carbaryl, cyfluthrin, deltamethrin, lambda-cyhalothrin, and permethrin.  Horticultural oil, insecticidal soap, pyrethrins and spinosad can also be effective.  To achieve the best results, apply insecticides when larvae are small and before they have caused significant damage.  VLB adults can be managed with contact insecticides, if needed, but are mobile and more challenging to control.  Systemic products (e.g., clothianidin and imidacloprid) applied as soil drenches can also be effective, but apply these products after flowering (to minimize any risks to pollinators), but before VLB damage occurs to achieve the best protection.

For more information on viburnum leaf beetle: Contact your county Extension agent.

Professional Guide to Emerald Ash Borer Insecticide Treatments – Pest Alert

Emerald ash borer insecticide treatment considerations.  A variety of insecticide products and application methods are available to professionals for control of the emerald ash borer (EAB).  Since the presence and infestation level of EAB is quite difficult to determine at early stages of an infestation, insecticide treatments may be merited to mitigate damage by EAB.  However, not all ash trees should be treated as some may be too extensively compromised or in poor condition to receive treatment.  Due to the expense of yearly insecticide treatments, one should consider the value of a particular ash tree in relation to insecticide treatment costs before making any treatments.  In addition, consider the health of each tree before treating.  Research suggests that insecticide treatments are significantly more effective on EAB-infested ash trees with less than 50% canopy thinning.  Insecticide treatments are not suggested for trees with greater than 50% canopy thinning.  Ash trees with greater than 50% canopy thinning should be removed and destroyed in accordance with established state and federal guidelines.  For additional information on this topic, see University of Wisconsin Garden Pest Alert XHT1215, Is My Ash Tree Worth Treating for Emerald Ash Borer.

Emerald ash borer insecticide treatment options.  Insecticide products that are available for use by professionals, with information on appropriate application methods and application timings, are summarized in Table 1.  These products include:

  • Ace-Jet (acephate)
  • ACECAP Systemic Insecticide Tree Implants (acephate)
  • ArborMectin (emamectin benzoate)
  • AzaGuard (azadirachtin)
  • Bifen XTS (bifenthrin)
  • Boxer Insecticide-Miticide (emamectin benzoate)
  • Dinocide, Dinocide HP (dinotefuran)
  • IMA-jet, IMA-jet 10 (imidacloprid)
  • Imicide, Imicide HP (imidacloprid)
  • Inject-A-Cide B (bidrin)
  • Mectinite (emamectin benzoate)
  • Merit 2F, Merit 75 WP, Merit 75 WSP (imidacloprid)
  • OnyxPro (bifenthrin)
  • Pointer (imidacloprid)
  • Safari (dinotefuran)
  • Tempo (cyfluthrin)
  • Transtect (dinotefuran)
  • Tree-äge, Tree-äge G4, Tree-äge R10 (emamectin benzoate)
  • Treeazin (azadirachtin)
  • TreeMec Inject (emamectin benzoate)
  • Xytect 2F, Xytect 75 WSP, Xytect 10% infusible (imidacloprid)
  • Zylam (dinotefuran)

University research indicates that soil drenches or injections of imidacloprid provide excellent EAB protection for small ash trees [less than six inches diameter at breast height (DBH)] in the first year following treatment.  Larger trees may require two consecutive years of treatment before they are effectively protected.  Thus, treatment of large trees should begin before the trees become infested.  While spring and/or fall applications are allowed on certain product labels, recent university research has indicated that spring applications have been more effective at controlling EAB and protecting canopy health.  Most insecticide treatments must be repeated each year.  Products containing emamectin benzoate are labeled to provide two years of protection.  Recent university research suggests that some of these products may provide more than three years of control with a single application when used at the highest labeled rate.

Trunk injections and implants require physically drilling or coring into a tree during the application of the insecticide.  Thus, use of these application methods has the potential to cause injury to trees (especially smaller trees), and may provide entry points for certain disease-causing fungi [e.g., Nectria, the cause of Nectria canker (see University of Wisconsin Garden Facts XHT1094 Nectria Canker)].

Table 1.  EAB insecticide treatments available to professionals*
Active Ingredient Product(s) Timing Application Method
Acephate ACE-Jet Mid-May to mid-June Trunk Injection
Acecap Implants Trunk Implant
Azadirachtin AzaGuard, Treeazin Early/mid-April to
early September
Trunk Injection
Bidrin Inject-A-Cide B Inject when infestation is evident Trunk injection
Bifenthrin Bifen XTS, OnyxPro Apply prior to or just at the time of adult emerge. Multiple applications may be needed Preventative bark and foliage cover sprays
Cyfluthrin Tempo
Dinotefuran Dinocide, Dinocide HP Late-April to late-May Trunk injection
Safari, Transtect, Zylam Soil drench, trunk spray
Emamectin benzoate ArborMectin, Boxer, Mectinite, Tree-äge, Tree-äge G4, Tree-äge R10, TreeMec April to September Trunk injection
Imidacloprid Merit 75 WP, Merit 75 WSP, Merit 2F, Xytect 2F, Xytect 75WSP, and others Mid-April to late-May

and/or

Early-Sept. to mid-October

Soil injection or drench
IMA-jet, IMA-jet 10, Imicide, Imicide HP, Pointer, Xytect 10% Mid-April to mid-May Trunk injection

The University of Wisconsin does not endorse any one specific commercially available insecticide.  Products discussed in this fact sheet have been evaluated in a variety of university research tests on EAB (http://www.emeraldashborer.info/).  No matter which insecticide you use, always read and follow all label instructions.  Avoid skin contact with insecticides and safely store insecticides out of the reach of children.

For more information on controlling emerald ash borer:
See https://eab.russell.wisc.edu/, https://datcpservices.wisconsin.gov/eab/ or http://www.emeraldashborer.info/, University of Wisconsin Pest Alerts XHT1181 (Homeowner Guide to Emerald Ash Borer Insecticide Treatments) and XHT1215 (Is My Ash Tree Worth Treating for Emerald Ash Borer).

Cranberry Flea Beetle

The cranberry flea beetle (CFB) or redheaded flea beetle, Systena frontalis, is native to the United States ranging in the east from Maine to Florida and in the west from Texas to Montana.  CFB has historically been an important pest in nurseries, greenhouses and agricultural crops.  In the last decade, the insect has become an emerging, sporadic pest on cranberries.  CFB has likely always been present in cranberry marshes in Wisconsin but probably was not a problem in the past because of widespread use of broad-spectrum insecticides for control of other cranberry insect pests.  The relatively recent appearance of problems with CFB may be a consequence of growers using more selective insecticides for pest control.

A cranberry flea beetle adult (left) and larva (right). Note the fleshy projection at the rear end of the larva (white arrow). Photos courtesy of Shannon Schade (left) and Tim Dittl, UW-Madison (right).
A cranberry flea beetle adult (left) and larva (right). Note the fleshy projection at the rear end of the larva (white arrow). Photos courtesy of Shannon Schade (left) and Tim Dittl, UW-Madison (right).

Appearance:  Adult CFBs are shiny, black beetles with a reddish head.  They are approximately 1/10 to 1/4 inch long with antennae nearly half as long as their bodies.  They also have enlarged hind legs, which they use for jumping when disturbed.  Adult females are slightly larger than males.  Larvae are 1/5 to 1/4 inch long with a fleshy projection at the tip of their rear ends.

Host Range:  CFB has a very broad host range that includes many woody and herbaceous plants.  In cranberry production areas, the insect prefers to feed on weeds such as marsh St. John’s-wort, Joe-pye weed, smartweed, jewelweed, and hardhack spirea.  If these weedy species are not present or are kept mowed, CFB will move to cranberry beds and feed on cranberry foliage and fruits.  CFB is also an occasional pest of other commercial crops, including alfalfa, beans, beets, blueberries, cruciferous vegetables, eggplant, grapes, horseradish, potato and sweet potatoes.

Symptoms and Effects:  CFB larvae feed on cranberry roots and underground runners.  When CFB infestations are severe, larval feeding can lead to girdled roots and vine death.  Adult CFBs feed on foliage and on the surface of cranberry fruit.  Severe adult infestations can lead to skeletonization of leaves (i.e., loss of the tissue between veins) and death of upright vines.  Heavy feeding by adults can also impact bud development, leading to yield reductions the year following an infestation.  Because adults prefer areas of lush growth, adult CFB populations and damage are usually patchy.

Life Cycle:  In Wisconsin, female CFBs deposit single eggs into the soil in late summer through early fall, and the eggs serve as the overwintering stage of the insect.  In the spring, the eggs hatch, and CFB larvae feed on roots from June through August.  Larvae eventually pupate (this stage of the insect’s life cycle has not been formally described) and adults begin to emerge in July and are present through September.  In Wisconsin, CFB has one generation per year.

Scouting Suggestions:  Monitoring for CFB focuses on adult beetles, because finding larvae in the soil is difficult.  To evaluate CFB numbers, use a sweep net to capture adults.  Be sure to sample thoroughly across different areas within a cranberry bed to account for the patchy distribution of CFB adults.  There is no established action threshold for CFB in cranberry.  However, University of Maine Extension recommends taking action if you find more than 15 CFB per 25 sweeps in a cranberry bed.

Leaf damage with skeletonization (left) and root damage (right) due to cranberry flea beetle feeding. Photos courtesy of Tim Dittl, UW-Madison.
Leaf damage with skeletonization (left) and root damage (right) due to cranberry flea beetle feeding. Photos courtesy of Tim Dittl, UW-Madison.

Control:  Current management of CFB targets the adult stage.  If scouting indicates significant numbers of adult CFBs, consider using insecticide sprays for control.  Products that are effective against CFB adults include neonicotinoids (e.g., clothianidin, thiamethoxam, acetamiprid, dinotefuran), diamides (e.g., chlorantraniliprole, cyantraniliprole), spinosyns (e.g., spinetoram), organophosphates (e.g., chlorpyrifos, phosmet, diazinon) and carbamates (e.g., carbaryl).  When using insecticides, be sure to alternate use of at least two active ingredients in different IRAC chemical classes to help delay the development of insecticide resistance.  Also be sure to consider any adverse effects that the insecticides you use may have on non-target and beneficial insects.  Check University of Wisconsin Bulletin A3276 (Cranberry Pest Management in Wisconsin), available at https://learningstore.extension.wisc.edu/, for additional insecticide recommendations.

DO NOT use soil insecticide applications in an attempt to target CFB larvae.  Such treatments are not effective.

Alternative management strategies for CFB have not been adequately researched.  Because CFBs prefer to feed on weed species, researchers speculate that use of trap crops may eventually become a useful management strategy.  In the area of biocontrol, current research at the University of Wisconsin-Madison indicates that native Wisconsin entomopathogenic nematodes significantly suppressed CFB larvae populations in soil.  At this time however, these nematodes are not available commercially.  In addition, work is needed to identify natural enemies of CFB that might be used to help manage the pest.

For more information on cranberry flea beetle:  Contact your county Extension agent.

Black Stem Borer

Black stem borer (BSB), Xylosandrus germanus, also known as the alnus ambrosia beetle, is an invasive beetle from Asia (primarily Japan, Korea, Vietnam, China, and Taiwan) that was accidentally introduced into central Europe and North America.  BSB has traditionally been considered a serious pest of nursery and landscape trees, but has also been reported as a pest of fruit crops.  In the 1930’s, BSB was first detected in grapes in New York, and more recently, BSB has become increasingly active on fruit trees, particularly in New York and Michigan.

A black stem borer entry hole (left), a compressed sawdust toothpick emerging from an entry hole (right), and an adult black stem borer (inset). Photos courtesy of Deborah Breth (Cornell Cooperative Extension), Chris and Juli McGuire (Two Onion Farm), and Maja Jurc (University of Ljubljana), respectively.
A black stem borer entry hole (left), a compressed sawdust toothpick emerging from an entry hole (right), and an adult black stem borer (inset). Photos courtesy of Deborah Breth (Cornell Cooperative Extension), Chris and Juli McGuire (Two Onion Farm), and Maja Jurc (University of Ljubljana), respectively.

Since 2013, BSB has been detected in 21 counties in Wisconsin (Crawford, Dane, Grant, Iowa, Jefferson, Kenosha, La Crosse, Lafayette, Manitowoc, Milwaukee, Ozaukee, Portage, Racine, Richland, Rock, Sauk, Shawano, Sheboygan, Trempealeau, Vernon, and Waukesha).  Prior to 2019, BSB had only been found in Wisconsin at lumberyards and wood waste disposal sites.  However, in June 2019, BSB was confirmed in a commercial apple orchard in Lafayette County, WI.  The reason for the movement of BSB from ornamentals to fruit trees is unclear, but this movement raises concerns about damage that BSB may cause in commercial orchards in the future.

Appearance:  Adult BSBs are small insects that are between 1/8 and 1/16 inches in length.  They are reddish brown to nearly black in color and cylindrical.  Only females are known to fly.  Larvae are small, white, legless grubs.

Host Range:  BSB can attack over 200 species of ornamental trees including oak, elm, red maple, beech, hickory, chestnut, magnolia, pear, dogwood, black cherry, tupelo, and black walnut.  It can also attack fruit crops such as apple, apricot, cherry, grape, pear and plum.

Symptoms and Effects:  Wilting and dieback are typically the first noticeable symptoms of a BSB infestation.  These symptoms are the result of defense responses on the part of the tree to the presence of BSB.  General tree decline and eventual death often follow.  Small holes in the lower trunks of infested trees are another typical symptom of a BSB infestation.  Columns of compressed sawdust (called “toothpicks”) often emerge from these holes.  Dry, dark-colored, blistery bark and oozing sap are other typical symptoms.

BSB activity may occur in association with plant diseases such as fire blight (see University of Wisconsin Garden Facts XHT1090, Fire Blight) and other canker diseases (e.g., Fusarium canker).  It is unclear if stress from these diseases makes trees more attractive to BSB, if BSB is spreading disease-causing organisms, or both.

Life Cycle:  BSB overwinters as adults (primarily females) in host trees.  Overwintering adults are usually found in higher numbers in wooded areas, and they move to other nearby trees (including orchard trees) from these areas in the spring.  Overwintering adults become active in late April to early May following one to two consecutive days where temperatures are 68°F or higher.  After mating, females (the only adults known to fly) search for new hosts.  They can fly more than 330 feet to colonize new trees.  BSB prefers trees that are three inches or less in diameter.

Trees stressed from flooding, frost injury, and drought are particularly attractive to BSB.  Stressed trees produce several types of volatile chemicals (including ethanol) that attract BSB.

A black stem borer trap. Photos courtesy of Deborah Breth (Cornell Cooperative Extension).
A black stem borer trap. Photos courtesy of Deborah Breth (Cornell Cooperative Extension).

Once females locate suitable trees, they bore holes (approximately 1/16 inches in diameter) in the trunks, typically in the lower two to three feet.  Females create a network of tunnels (galleries) under the bark where they lay eggs and where their larvae develop.  Females lay one egg per day and can deposit up to 18 eggs.  After eggs hatch, larvae develop through three stages (instars) before maturing into adults.  This process takes approximately 30 days.  New adults typically emerge in July and a second round of mating, tunneling, egg-laying and larval development occurs.  The second generation of BSB adults (which overwinters) typically begins to appear around the end of August and into September.

Interestingly, BSB adults and larvae do not feed on plant tissue, but on a symbiotic fungus (Ambrosiella hartigii) that females carry in internal pouches (called mycangia).  Females disseminate the fungus in their galleries where it grows and spreads providing a food source for the beetles.

Scouting Suggestions:  Routinely examine trees for typical symptoms of BSB (as described above).  Also consider using ethanol-baited traps to monitor the flight activity of adult females in the spring.  Make traps from one- or two-liter plastic bottles, cutting two to four windows from the sides.  Cap the modified bottles and hang them upside down at a height of 20 inches.  Concentrate traps around sensitive trees (particularly orchard trees) near wooded areas.  Bait traps by adding one cup of vodka (which serves as the ethanol attractant and also the drowning solution) or by hanging a ready-made ethanol lure inside the trap and filling the bottom of the trap with a small amount of a drowning solution (e.g., soapy water or antifreeze).  DO NOT use rubbing alcohol in these traps.  Check traps at least weekly for drowned beetles.  Identification of BSB requires use of a microscope and proper training.  If you suspect BSB, send a specimen or good digital photo to the UW-Madison Insect Diagnostic Lab (https://insectlab.russell.wisc.edu/).

Control:  Remove and burn infested trees where 75% or more of the branches are dying.  Mow (with a flail mower) or burn large brush piles as these may harbor beetles that can cause new infestations.  Minimize stresses on trees (as described above) to make them less attractive to BSB.  Insecticide treatments may be useful for protecting trees in areas where BSB is a problem.  Young trees near woodlot edges are at greatest risk of injury and the most likely to benefit from insecticide applications.  However, application of insecticides should be considered carefully as these sprays can negatively impact pollinators.  If you decide to spray, treat trunks in the spring when BSB females emerge.  This occurs at around 75 growing degree days base 50°F (see University of Wisconsin Garden Facts XHT1086, Degree Day Calculation for details).  Follow with a second trunk spray as needed.  Use products containing pyrethroids (particularly permethrin).  These products can be used on apple trees where they will help control BSB, as well as green fruitworm and spotted tentiform leafminers, two other apple insect pests.  Note that because BSB does not feed on woody tissue but rather on the Ambrosiella fungus, systemic insecticides that control other borers will not be effective against BSB.

For more information on black stem borer:  Contact your county Extension agent.

Ralstonia Wilt – Pest Alert

What is Ralstonia wilt?  Ralstonia wilt (also sometimes known as Southern wilt) is a typically lethal disease that affects over 250 plants in over 40 plant families.  Susceptible greenhouse-grown ornamentals include, but are not limited to, plants in the genera Capsicum, Cosmos, Cyclamen, Dahlia, Fuschsia, Gerbera, Hydrangea, Impatiens, Lantana, Nasturtium and Pelargonium.  Vegetables such as eggplant, pepper, potato and tomato, as well as tobacco, are also susceptible.  Ralstonia wilt was first reported on geraniums (Pelargonium spp.) in Wisconsin in 1999.  In 2020, the disease was reported on Fantasia® ‘Pink Flare’ geraniums in Michigan.  Potentially infected ‘Pink Flare’ geraniums were also distributed to 38 other states including Wisconsin.

Yellowing and wilting characteristic of Ralstonia wilt. Photo courtesy of WI DATCP
Yellowing and wilting characteristic of Ralstonia wilt. Photo courtesy of WI DATCP

What does Ralstonia wilt look like?  Symptoms of Ralstonia wilt in geraniums are similar to those associated with bacterial blight (caused by Xanthomonas campestris pv. pelargonii).  Initially, lower leaves of infected plants yellow and wilt, then die.  Yellowing and death of upper leaves follow.  Symptoms may initially occur on only one side of the plant.  Internally, the water-conducting tissue of the plant browns, and then the entire stem rots from the inside out.  Eventually, infected plants die.

Where does Ralstonia wilt come from?  Ralstonia wilt is caused by the bacterium Ralstonia solanacearum (formerly Pseudomonas solanacearum).  This bacterium is commonly found in tropical, sub-tropical and warm temperate climates, but it is not believed to survive cold temperatures such as those typical of Wisconsin winters.  The bacterium can be moved in symptomless plants or cuttings, or in contaminated soil and plant debris (where the pathogen can remain dormant for many years).  Several subgroups (i.e., races and biovars) of R. solanacearum have been recognized, each with a different host range.  R. solanacearum race 3, biovar 2 is of particular concern because it causes a serious disease of potato called brown rot.  In addition, this race/biovar has been listed as a select agent by the U.S. government and is considered to have potential to be developed as a bioterrorist weapon against U.S. agriculture.

How do I save plants with Ralstonia wilt?  There are no known treatments that will save plants affected by Ralstonia wilt.  If you believe your plants are suffering from this disease, immediately contact your local department of agriculture or county Extension agriculture or horticulture agent to arrange for confirmatory testing.  If you live in Wisconsin, you can contact the UW-Madison Plant Disease Diagnostics Clinic (see below for contact information) for assistance.  If your plants test positive for R. solanacearum race 3, biovar 2 the United States Department of Agriculture Animal and Plant Health Inspection Service (USDA APHIS) must be notified and this organization will provide guidance on proper disposal of contaminated plants, as well as decontamination of greenhouses or other sites where contaminated plants have been grown.

How do I avoid problems with Ralstonia wilt in the future?  Start by purchasing and growing pathogen-free plant cuttings.  Keep plants from different suppliers physically separated by at least four feet to minimize the risk of cross contamination should a shipment of plants prove to be contaminated.  Because R. solanacearum is easily moved with soil or water, minimize splashing or any other movement of water or soil from plant to plant when watering.  When taking cuttings or trimming plants, be sure to clean cutting tools between cuts using an approved disinfectant.  For a complete list of such products, contact the UW-Madison Plant Disease Diagnostics Clinic (see below for contact information).  Also wear disposable gloves (nitrile are best) when handling plants, and change gloves between working with different geranium varieties.  This will minimize the possibility of moving R. solanacearum by touch.  If gloves are not available, wash your hands frequently and thoroughly (especially between geranium varieties) with lots of soap and water or with an alcohol-based hand sanitizer.  Remove and destroy weeds or weed debris as these can harbor the pathogen.  Finally, do not grow plants in a greenhouse where the disease has occurred unless it has been properly decontaminated.

For more information on Ralstonia wilt or help in diagnosing this problem:  Contact Brian Hudelson, Plant Disease Diagnostics Clinic, University of Wisconsin-Madison, 1630 Linden Drive, Madison, WI  53706-1598 [phone: (608) 262-2863, fax: (608) 263-3322, email:  pddc@wisc.edu].

Sudden Oak Death – Pest Alert

What is sudden oak death?  Sudden oak death (SOD), also called Ramorum leaf blight or Ramorum dieback, is an oftentimes lethal disease that has caused widespread death of tanoak (Lithocarpus densiflorus), coast live oak (Quercus agrifolia), California black oak (Quercus kelloggii), and Shreve oak (Quercus parvula var. shrevei) in California.  The disease can affect or has been reported in association with a wide range of woody and herbaceous plants including, but not limited to bigleaf maple (Acer macrophyllum), Bodnant viburnum (Viburnum X bodnantense), ‘Brouwer’s Beauty’ pieris (Pieris floribunda X japonica), California bay laurel (Umbellularia californica), California buckeye (Aesculus californica), California coffeeberry (Rhamnus californica), California honeysuckle (Lonicera hispidula), canyon live oak (Quercus chrysolepis), coast redwood (Sequoia sempervirens), doublefile viburnum (Viburnum plicatum var. tomentosum), douglas-fir (Pseudotsuga menziesii var. menziesii), evergreen huckleberry (Vaccinium ovatum), Formosa firethorn (Pyracantha koidsumii), ‘Forest Flame’ pieris (Pieris formosa X japonica), Himalaya pieris (Pieris formosa), Japanese camellia (Camellia japonica), Japanese pieris (Pieris japonica), laurustinus (Viburnum tinus), madrone (Arbutus menziesii), manzanita (Arctostaphylos manzanita), rhododendron (Rhododendron spp.), Sasanqua camellia (Camellia sasanqua), toyon (Heteromeles arbutifolia), western starflower (Trientalis latifolia), and witch hazel (Hamamelis virginiana), Burkwood viburnum (Viburnum X burkwoodii), California hazelnut (Corylus cornuta), Camellia X williamsii, cascara (Rhamnus purshiana), Chinese pieris (Pieris formosa var. forrestii), common lilac (Syringa vulgaris), David viburnum (Viburnum davidii), drooping leucothoe (Leucothoe fontanesiana), European beech (Fagus sylvatica), European cranberrybush viburnum (Viburnum opulus), European turkey oak (Quercus cerris), European yew (Taxus baccata), fragrant viburnum (Viburnum farreri), grand fir (Abies grandis), Holm oak (Quercus ilex), horse-chestnut (Aesculus hippocastanum), lingonberry (Vaccinium vitis-ideae), mountain laurel (Kalmia latifolia), Northern red oak (Quercus rubra), Pieris formosa var. forrestii X Pieris japonica, poison oak (Toxicodendron diversiloba), Prague viburnum (Viburnum X pragense), reticulate camellia (Camellia reticulata), salmonberry (Rubus spectabilis), Southern red oak (Quercus falcata), strawberry tree (Arbutus unedo), sweet chestnut (Castanea sativa), Viburnum X carlcephalum X Viburnum utile, Victorian box (Pittosporum undulatum), wayfaringtree viburnum (Viburnum lantana), and wood rose (Rosa gymnocarpa).

Rapid wilting and die back of branch tips can be a symptom of ramorum dieback.
Rapid wilting and die back of branch tips can be a symptom of ramorum dieback.

SOD was first reported in the US in California and has subsequently been found in other US states, including in Wisconsin in 2019.  SOD has also been reported in Europe.

What does sudden oak death look like?  Symptoms of SOD vary depending upon the plant species infected.  On some hosts, infections occur primarily on leaves leading to light brown leaf spots and blotches.  These leaf symptoms may be indistinguishable from other, more common, leaf spots and blights, or may mimic sunburn or leaf scorch symptoms.  Twigs and branches that become infected often wilt, forming a “shepherd’s-crook”, and subsequently die back.  Infection of tree trunks leads to cankers (i.e., sore-like areas) that produce large amounts of an amber to black colored ooze.  This ooze can dry to form a stained area on the bark.  Removing the bark over the affected area will reveal discolored wood beneath that sometimes (but not always) has a black border.  Cankers can eventually expand to girdle trunks, thus resulting in the death of the tree or shrub.  Trunk infections appear not to extend into the root system of the plant.  Once SOD cankers develop, other pathogens may invade the infected areas, accelerating tree or shrub death and complicating the diagnosis of the disease.

Where does sudden oak death come from?  SOD is caused by the fungus-like water mold Phytophthora ramorum, which was first recognized as a pathogen in 1995.  Phytophthora ramorum can be spread over long distances through movement of infected plants or infested plant parts.  The organism can also be moved with contaminated soil (e.g., on vehicle tires, tools, or shoes), or in contaminated water.  Once established on plants in a given location, the organism produces reproductive structures (called sporangia) that can be moved from plant to plant by rain splash, or wind.  Phytophthora ramorum was introducing into Wisconsin in 2019 on nursery stock grown in the state of Washington.

Ramorum leaf blight symptoms can mimic those of other leaf spots and blights.
Ramorum leaf blight symptoms can mimic those of other leaf spots and blights.

How do I save a plant with sudden oak death?  If you believe you have seen a plant that has SOD, please IMMEDIATELY submit a sample to the UW-Madison Plant Disease Diagnostics Clinic (PDDC).  See below for address details.  Double bag suspect plant tissue in sealable plastic bags and place the bagged specimen in a box or envelope for shipping.  Include contact information (complete address, phone number, email address) in a separate sealable plastic bag with the sample.  Tape over all of the edges of boxes and envelopes used for shipping to keep everything sealed inside.  Write on the box or envelope that the box or envelope contains a suspect SOD sample.  If you have questions about collecting or submitting a sample, contact PDDC staff at (608) 262-2863 or at pddc@wisc.edu.

Because Phytophthora ramorum is a regulated, quarantined pathogen, DO NOT remove the affected plant (or parts thereof) or take the plant from the site where it is located, other than to collect a specimen for submission for a diagnosis.  Be sure to decontaminate any tools or other items that come into contact with the plant (including those used to collect a diagnostic sample) by treating them for at least 30 seconds in 10% bleach.  Thoroughly rinse and oil tools after decontamination to prevent rusting.  If a plant tests positive for Phytophthora ramorum, it will be removed and destroyed to help prevent further spread of the pathogen.

How do I avoid problems with sudden oak death in the future?  Carefully inspect any new nursery stock upon delivery (or prior to purchase, if possible) for symptoms of SOD.  Keep new stock isolated from older stock as long as possible, to minimize possible movement of the pathogen should the disease develop after plants have arrived.  If you see any suspect symptoms, alert the PDDC so that arrangements can be made for proper testing for Phytophthora ramorum.

For more information or help in diagnosing sudden oak death:  Contact Brian Hudelson, UW-Madison Plant Disease Diagnostic Clinic, Department of Plant Pathology, University of Wisconsin-Madison, 1630 Linden Drive, Madison, WI  53706-1598, phone: (608) 262-2863, email: pddc@wisc.edu, see the USDA APHIS sudden oak death website https://www.aphis.usda.gov/aphis/ourfocus/planthealth/plant-pest-and-disease-programs/pests-and-diseases/phytophthora-ramorum/sod, or contact your County Extension agent.

African Fig Fly – Pest Alert

The African fig fly (AFF), Zaprionus indianus, is an invasive vinegar fly closely related to flies in the genus Drosophila [which includes the common vinegar fly (also sometimes called the common fruit fly) and spotted-wing drosophila (SWD)].  AFF is native to Africa, Eurasia and the Middle East.  It was first detected in the United States in Florida in 2005, where it is now well established.  In 2012, AFF (a single adult) was first detected in Wisconsin.  In 2017, larger numbers of AFF were found in the state in traps used to monitor for SWD.

An African fig fly adult. (Photo courtesy of Benjamin Davidson)
An African fig fly adult. (Photo courtesy of Benjamin Davidson)

Outside of Wisconsin, AFF has had its biggest economic impact in commercial fig production, and has not been found to have a significant economic impact on other agricultural crops.  In Wisconsin, the potential economic impact of AFF on fruit and other crops is not yet known.  Because AFF reproduces readily and can rapidly expand its range, careful monitoring for this insect in the state is warranted.

Appearance:  The adult AFF is slightly larger than the common vinegar fly or SWD, and has a light-colored body and bright red eyes.  An adult AFF has four black-bordered, white stripes that run along each side of its head and thorax (but not its abdomen).  These stripes can easily be seen using a hand lens and are not found on any other vinegar flies in Wisconsin.  An AFF larva (maggot) is legless and has a single hook-like tooth at its mouth-end.  The maggot uses this tooth to feed on rotted berries and other soft fruit tissues.  AFF maggots are nearly indistinguishable from maggots of common vinegar flies and SWD.

Host Range:  AFF can feed on a large number of fruit crops grown in Wisconsin, including blackberries, blueberries, grapes, peaches, raspberries and strawberries, with grape being a preferred host.

Symptoms and Effects:  Given that AFF is a newcomer to Wisconsin and its temperate climate, predicting which fruits the insect will affect, and to what extent, is difficult.  What is known about AFF is that it cannot initiate damage to intact, ripe fruit; it can only feed on and lay eggs inside of overripe or already damaged fruit.  The insect contributes to additional breakdown and decay of these fruit.  In Wisconsin, AFF and SWD (which can damage intact, ripe fruit) will likely occur together at a given location, and will likely interact.  AFF may end up laying eggs in fruit damaged by SWD, possibly leading to an increase in AFF populations.  The effects of AFF on SWD populations are not clear at this time.  However, some research conducted in grapes suggests that where AFF and SWD occur together, they may compete, leading to increased numbers of AFF and lower numbers of SWD.

Life Cycle:  As an insect native to the tropics, AFF will likely not be able to survive even a mild winter in Wisconsin; in fact, AFF does not appear to overwinter even as far north as Virginia.  However, AFF can travel long distances on air currents, and could potentially travel from the southern US to Wisconsin in the spring and summer, leading to fruit infestations in the state in the summer and fall.  AFF has only been detected in Wisconsin in 2012 and 2017, suggesting that if the insect does cause problems in Wisconsin, these problems will not likely be a yearly occurrence.

Exactly how many generations of AFF might develop in Wisconsin in a given year is not known.  In the laboratory (at 75°F), AFF develops from egg to adult in 20 days and females lay, on average, 60 eggs.  Based on its short generation time and ability to produce numerous eggs, AFF populations could potentially build quickly within a given year, once the insect arrives in Wisconsin.

Monitoring:  Monitor for AFF using the same traps that you would use to monitor for SWD.  You can buy commercially available traps, or alternatively, you can make simple, inexpensive traps using a 32-ounce clear plastic container with a lid.  To allow adult flies to enter the trap, drill or melt ten 3/16 inch diameter holes around the top of the container.  Bait traps with one tablespoon active dry yeast and four tablespoons sugar in twelve ounces of water.  Alternatively, use a two-inch layer of apple cider vinegar in the bottom of the container.

Add one to two drops of unscented dish soap to the trap to break the surface tension of the liquid so that flies are more likely to

A homemade vinegar fly trap made from a 32-ounce clear plastic container with a lid. (Photo courtesy of Emma Pelton)
A homemade vinegar fly trap made from a 32-ounce clear plastic container with a lid. (Photo courtesy of Emma Pelton)

drown.  Hang traps in a shaded plant canopy where fruit is present.  For strawberries, place traps on the ground.  Check traps and replace liquid bait weekly, using a hand lens to identify trapped insects.  Be careful not to pour bait on the ground near the traps as this will confuse flies and reduce the effectiveness of the traps.  DO NOT bother testing fruit directly to determine infestation rates for AFF, as AFF larvae will be indistinguishable from those of other vinegar flies (e.g., common vinegar fly and SWD).

Control:  Because AFF cannot cause damage to sound fruit, and because recorded populations of AFF in Wisconsin have been low, AFF control may not be needed unless/until severe outbreaks occur.  Control methods recommended for SWD will likely also help control AFF.  In particular, cultural practices such as removing all damaged or rotting fruit and then solarizing (heating) or freezing this material to kill fly larvae may slow buildup of AFF at a given location in a given growing season.  However, because AFF is able to move over long distances from areas in the south where it can easily overwinter, reintroduction of the insect will be possible even if you follow strict sanitation practices.

Exclusion netting, which has been used with some success to manage SWD, will likely also help manage AFF.  When using netting, use a mesh size that is 1/32 inch or smaller.  Start using netting after early fruit set (so as not to interfere with pollination), but before fruit begins to ripen.  Make sure the mesh completely covers fruit with no gaps between sheets of netting or at the soil surface.  Any opening can provide an entry point for AFF.

Chemical control for AFF is not currently recommended in Wisconsin.  Observed AFF populations have not been high enough to warrant such treatments.  If spraying for AFF does become necessary, choose insecticides (e.g., spinosyns, carbamates and organophosphates) that also provide control of SWD.  As always, rotate active ingredients that are in different IRAC chemical classes (i.e., have different modes of action) to delay development of insecticide resistance.  For details on IRAC chemical classes, see https://www.irac-online.org/modes-of-action/.  Also, be sure to consider the effects of the products that you select, on non-target insects, particularly beneficial insects such as bees.  Please check the most recent Midwest Fruit Pest Management Guide (see https://learningstore.uwex.edu) for full product recommendations.

If you suspect that you have found an AFF, please contact the University of Wisconsin-Madison Insect Diagnostic Lab at (608) 262-6510, idl@entomology.wisc.edu or http://labs.russell.wisc.edu/insectlab/contact-us/.

For more information on African fig fly, as well as other vinegar flies:  See University of Wisconsin Garden Facts XHT1102 (Fruit Flies in the Home), University of Wisconsin Garden Facts XHT1237 (Spotted Wing Drosophila), or contact your county Extension agent.

Is My Ash Tree Worth Treating for Emerald Ash Borer? – Pest Alert

This factsheet addresses some of the most frequently asked questions regarding the treatment of ash trees for emerald ash borer (EAB), and the removal and disposal of infested trees.

High value ash trees are candidates for treatment for emerald ash borer.
High value ash trees are candidates for treatment for emerald ash borer.

When should I consider treating my ash tree for EAB?Based on current research, EAB treatments are suggested only for ash trees located within 15 miles of a confirmed EAB site, or for trees located within a quarantined area.  Insecticide treatments are not necessary for ash trees located outside of these areas.  Even within the 15-mile radius, not all trees should be treated.  Due to the expense of insecticide treatments for EAB, consider the value of a particular ash tree in relation to insecticide treatment costs before making any treatments.  Proper use of EAB insecticides can help maintain the health of high value ash trees over time.  Lower value ash trees are not ideal candidates for EAB insecticide treatments.

How do I know if my ash tree has value?  Ash trees can be a valuable part of the landscape.  A properly cared for ash tree can increase property value, provide environmental benefits such as runoff and erosion mitigation, and reduce electricity costs by shading a home.  Determining tree value can be subjective.  Qualities to consider when assessing value include (but are not limited to) a tree’s overall health, shape, location with respect to landscape design, and appearance through the seasons, as well as whether or not a tree provides shade.  A healthy ash that is properly located in the landscape, has a nice shape and good fall color, and provides shade has value.  An ash tree that is not healthy due to disease or insects, has poor shape or structural damage, is otherwise unattractive, or is in a bad location (e.g., near a power line) is of lower value.

How do I know if there are ash trees in my area that are infested with EAB?  The Wisconsin Department of Agriculture Trade and Consumer Protection (DATCP) keeps track of EAB infestations in the state.  Visit the Wisconsin DATCP Emerald Ash Borer Resource Guide website (http://datcpservices.wisconsin.gov/eab/) and view the interactive map.  You can also contact your local county UW-Extension office to see if EAB has been found in your area.

How do I know if my ash tree has EAB?  Symptoms of an EAB infestation can include canopy thinning starting in the upper portion of the tree, epicormic sprouting (i.e., formation of sprouts) along the trunk, bark splitting, and woodpecker damage.  These symptoms indicate general tree stress, and can be due to EAB.  However, they also can be caused by diseases or insects other than EAB.  Specific signs of EAB include D-shaped exit holes (~3/16 inch wide) in the bark of the tree, S-shaped larval tunnels and/or larvae (cream colored, up to 1½ inches long) beneath the bark, and adults (metallic green, ~3/8 inch long).  Visit the UW-Madison Emerald Ash Borer in Wisconsin website (https://eab.russell.wisc.edu) for additional information on the symptoms and signs of EAB.

If I decide to treat my ash tree, will I have to treat every year?  In most cases, yes.  Most insecticides registered for EAB management require yearly applications to effectively protect a tree.  Products containing the active ingredient emamectin benzoate, are labelled for two years of protection.  Products containing emamectin benzoate are trunk-injected insecticides intended for use by professional insecticide applicators (e.g., certified arborists).  Such products can effectively protect an ash trees if the tree is treated every other year.

Can I treat an ash myself or do I have to call an arborist?  If your ash is smaller than 47 inches around the trunk at chest height [i.e., 15″ diameter at breast height (DBH)], you may be able to treat your ash tree yourself.  University of Wisconsin Pest Alert XHT1181 (“Homeowner Guide to Emerald Ash Borer Insecticide Treatments”) provides a list of products currently available for homeowner use.  If you decide to treat your own trees, be sure to read and follow all label instructions of the insecticide that you select to ensure that you use the product in the safest and most effective manner possible.

In some situations, hiring a certified arborist to treat your ash tree may be more desirable.  Professionals have access to specialized application equipment and additional insecticides not available to homeowners.  They are also trained to measure trees accurately, and assess the overall health of trees.  The Wisconsin Arborists Association website (http://www.waa-isa.org) has a list of certified arborists in the state.

Note that the University of Wisconsin does not endorse any insecticide products, and does not recommend any professional products over those available directly to homeowners.

Am I allowed to treat an ash tree in my yard between the sidewalk and street?   The answer to this question varies from municipality to municipality.  In many cases, municipalities have treatment or removal and replacement plans already in place.  Contact your local town, village or city to determine an appropriate strategy for protecting your sidewalk trees.

How much does it cost to treat an ash tree for EAB?  A single tree that is 32 inches around at chest height (approximately 10″ DBH) can be treated with a granular or liquid soil drench homeowner product for about $20-35/year.  Larger trees will require a larger amount of product and costs will be higher.  Arborist treatment costs vary depending on tree size and location, the insecticide selected, and the application method.  Other arborist-specific site visit charges may apply as well.  Consult at least two arborists in your area to discuss treatment options and costs.  To make an accurate comparison among service providers, make sure you know what insecticide will be used, the method of application, and how often treatments will be made.  An arborist will not be able to determine the exact cost of treatment for your specific ash tree without a site visit, but an arborist should be able to provide you with a cost estimate for a typical ash tree.

Do I have to remove my ash tree if it is infested with EAB?  Applying protective insecticide treatments to a healthy ash tree to prevent an EAB infestation is the best strategy for managing EAB.  However, if a tree becomes infested and the infestation is detected early, you may be able to treat your ash tree to prevent further damage, and help the tree recover.  Research suggests that insecticide treatments are significantly more effective on EAB-infested ash trees with less than 50% canopy thinning.  Insecticide treatments are not recommended for trees with greater than 50% canopy thinning; these trees should be removed.  Trees that become infested with EAB and are not treated will ultimately die and will need to be removed.

How much does it cost to remove an ash tree?  Typically, a small (less than 25 feet in height) ash tree may cost a few hundred dollars to be removed by an arborist.  Larger trees may cost $1,000 or more to be removed.  Individual factors (e.g., the proximity of the tree to structures, power lines, or other hazards) can significantly increase the cost of removal.  Tree removal costs also may vary from location to location in Wisconsin.  Ultimately, removing recently killed trees while they are structurally sound, rather than allowing them to deteriorate, may be safer and more cost effective.

How do I dispose of wood from an infested ash tree?  If you choose to remove an infested ash tree, check with your municipality to see if a wood disposal or utilization program is in place.  If you have a tree removed by a tree care service, the service may be able to handle the disposal of wood from the infested tree.  If you decide to use wood from an ash tree for firewood or other purposes, use it locally.  Transporting infested wood risks spreading EAB elsewhere in the state, and may be in violation of Wisconsin’s quarantine laws.  Information about Wisconsin’s firewood regulations can be found on the Wisconsin DATCP Emerald Ash Borer website (http://datcpservices.wisconsin.gov/eab/).

For more information on controlling emerald ash borer: