Ornamentals Insect and Mite Update – 2008-2009

David J. Shetlar, Ph.D.The “BugDoc”

The Ohio State University, OARDC & OSU Extension

Columbus, OH

© December 2008, D.J. Shetlar, all rights reserved

http://ohioline.osu.edu

Notes:

The OhioLine is the primary Internet site for OSU Extension. This site is where all our factsheets and recent bulletins are posted. Most of these are posted as web pages and/or downloadable PDF files. Use the search engine to more rapidly find our publications.

http://bygl.osu.edu

Notes:

The Buckeye Yard and Garden Line is a weekly posting of information on what Ohio State horticulture specialists are seeing across the state. Every Tuesday, from April through October, specialists have a phone discussion on what they are seeing and what is expected over the next week or two. Note takers summarize this discussion and add pictures, links to relevant web pages and other information. This is posted by noon on Thursday.

The P.E.S.T. Newsletter

available from:

Ohio Nursery & Landscape Association72 Dorchester SquareWesterville, OH 43081

614-899-1195800-825-5062

Notes:

I’ll be producing the P.E.S.T. Newsletter again this season. This newsletter is available by subscription through the Ohio Nursery and Landscape Association (onla.org). Every two weeks, from mid-March to mid-October, I present the “BugDoc” view of what is going on across Ohio in the insect world and I give my often unique perspectives on management and control. You can select the option to receive mailed hard copies or emailed PDF version and all subscriptions provide passwords to view the newsletter on a web site where color pictures and links to additional information are provided.

Come visit the BugDoc at:Come visit the BugDoc at:http://bugs.osu.eduhttp://bugs.osu.edu

We’ve Moved!

New Location

Notes:

You can also find information on my personal web site. I post recent PowerPoint talks in HTML and as downloads of the actual PowerPoints. There are also links to BugDoc factsheets, class notes and other goodies. If you forget how to get to this page, just enter in “Bugdoc” in Google search and my web page should be the first on the list!

New Insecticides• Acelepryn™ (=E2Y45 or chlorantraniliprole, a

new insecticide category from DuPont) – little ornamental experience but promising for a wide array of insects (beetles, bugs, leafminers, and CATERPILLARS!) – Registered in spring of 2008. REQUIRES 60 DAYS FOR ROOT UPTAKE!

• TREE-äge™ (Abamectin benzoate, an avermectin from Syngenta and marketed through Arborjet) – good EAB activity, but only by large injection holes!

Notes:

Probably the newest insecticides are Acelepryn from DuPont and Tree-age from Arborjet. Acelepryn represents a brand new category of insecticides and this insecticide was deemed a low risk pesticide by EPA. In fact, the toxicity and environmental footprint of this product was deemed low enough that there is no signal word on the label! Unfortunately, we have little data on the efficacy of Acelepryn for control of ornamental insects but we do know that it has significant caterpillar and beetle activity. Tree-age is a new insecticide that can be injected into trees for control of the Emerald ash borer. It has been shown to be as effective as most of the rest of the injection or drench insecticides.

Other New Insecticides• Meridian™ (thiamethoxam, a new neonicotinoid

from Syngenta) – excellent grub control, long lasting, etc. – Registration received in February 2007.

• Arena™ (clothianidin, a new neonicotinoid from Valent) – excellent broad spectrum control, including some caterpillar activity.

• Aloft™ (clothianidin plus bifenthrin from Arysta) – combo product with better surface knockdown.

• Safari™ (dinotefuran, a new neonicotinoid from Valent) – excellent broad spectrum control, rapid uptake, best armored scale activity, some caterpillar activity.

Notes:

While not the newest insecticides, Meridian, Arena and Aloft, and Safari are all neonicotinoids that you should be familiar with. Each one seems to have some unique properties of uptake and persistence in ornamentals. Meridian and Arena/Aloft are fairly rapid in uptake and both are excellent on beetles (including borers), sucking insects, soft scales, sawflies and fly leafminers. Safari is nearly water soluble and is the most rapidly taken up and translocated neonicotinoid. In fact, it can be sprayed on the bark of some trees to protect the trees from borers and other insects! Safari is also very good on a variety of armored scales and this should be tried if other neonicotinoids have failed.

Ohio Weather

• 2006 wetter than normal, 2007 dryer and hotter than normal!

• April, 2007 late hard freeze!

• Spring 2008 wetter than normal, southern 2/3 of Ohio no to spotty rains from July through September. Northern 1/3 of Ohio spotty, intense rains.

Notes:

I mention the weather to remind us that the extremes of drought, wet, heat and cold have placed many landscape trees and shrubs under severe stress. Stressed plants often have a difficult time defending themselves from diseases and insects or mites. Last year, the southern half of Ohio went through a major drought and there shouldn’t be many Japanese beetles next season. However, the northern third of the state had sufficient water to support a very large number of Japanese beetle grubs which means that the adults will be a real problem next year.

Insect and Mite Activity in 2008

• Bagworms & Mimosa Webworms!

• Patchy calico scale problems!

• Emerald Ash Borer – new outlying discoveries, almost weekly! PEOPLE are spreading it!

• Other borers – white pine weevil; Zimmerman pine moth; bark & ambrosia beetles.

• Elm fleaweevil – everywhere!

Notes:

The common bagworm has continued to be a major problem across Ohio where it can defoliate and kill pines, spruces, firs, arborvitae and junipers. In the past, this pest was primarily in the southern half of Ohio, but over the last two decades, it has moved steadily northward, even into Michigan! We’ll have to see if the -10 to -20 ºF winter weather will have killed the eggs this winter and move this pest back southward. Remember that the neonicotinoids (especially imidacloprid – Merit) is NOT a good choice to manage bagworms. Sprays of pyrethroids can be applied in mid- to late June for maximum control.

Notes:

Like the bagworm, the mimiosa webworm is also supposed to be freeze susceptible. It is a localized pest across most of Ohio and commonly will turn honeylocust trees brown by August. The larvae pupate in sheltered sites, so we’ll just have to wait to see if our ultra cold winter spells have knocked them out. Being a caterpillar, this pest is not well controlled with soil or basal drenches of imidacloprid (Merit) but some success has been reported with clothianidin (Arena/Aloft) and dinotefuran (Safari) drenches.

The Gypsy Moth – still moving across Ohio!

Notes:

The gypsy moth continues in its slow march westward across Ohio. Major defoliations occurred in Delaware and Springfield last year, and similar defoliations will likely occur this season. Unfortunately, with the State budgets on the decline, there will be little State management of this pest in the foreseeable future.

Caterpillar InsecticidesTraditional

• Dursban

• Sevin

• Orthene

Alternatives

• Tempo, Talstar, Deltagard, Scimitar, Astro

• Conserve

• Merit, Meridian (no!)

• Arena-Aloft. Safari? (suppression)

• Acelepryn?

• Bt

• Soaps or Oils

X

Notes:

Of the older insecticides, we still have use of Sevin and acephate (Orthene) but most commercial applicators have switched to the pyrethroids for caterpillar sprays. When it comes to systemic materials, the neonicotinoids – imidacloprid (Merit) and thiamethoxam (Meridian) – have “caterpillars” on their labels, but we see very poor control. Clothianidin (Arena/Aloft) and dinotefuran (Safari) seem to have greater action, but this should still be considered suppression. I have great hope for Acelepryn as a caterpillar-active insecticide, but it is so new we need more time to determine the ideal rates, timing and application techniques to maximize control. For those wanting less toxic materials, we still have spinosads (Conserve), BT, soaps and oils.

European Pine Sawfly

larvaeeggsadults

Notes:

Our most common sawfly defoliator in our landscapes continues to be the European pine sawfly, but some of the slug sawflies (roseslug, oakslug, pearslug) are increasing their action. Since these are actually the larvae of a wasp-like insect, they are susceptible to the neonicotinoids where caterpillars aren’t! In fact, you can protect Mugho pines from sawfly defoliation in May and June by applying imidacloprid as a soil drench in late October into November of the previous fall!

Sawfly Insecticides

Traditional

• Dursban

• Diazinon

• Sevin

• Orthene

Still/Now Available

• Pyrethroids (permethrin, resmethrin, esfenvalerate, bifenthrin, cyfluthrin)

• Merit, Safari, Arena & Aloft, Meridian

• Soaps or Oils

XX

Notes:

While carbaryl (Sevin), acephate (Orthene) and the pyrethroids are very good knock-down insecticides for sawfly control, the neonicotinoids are turning out to be excellent curative and preventive choices.

Calico scale adults on honeylocust (can be found on many deciduous landscape trees).

Calico scale nymphs on leaf undersurface.

Notes:

I’ve chosen the calico scale as an example of the soft scales common in Ohio. We have also seen localized problems with the lecanium scales, European elm scale, cottony maple scale and Fletcher scale. Most soft scales can be controlled when the crawlers and second instar nymphs are feeding on leaves or new needles of their hosts. Once the females have swollen up to lay eggs, controls are much less effective. Most of the neonicotinoids can be used effectively as preventive or early curative treatments.

Pine needle scale females. Note pinkish eggs at end of scale test (shell) and a settled crawler at upper left.

Group of pine needle scale settled crawlers (tan) and a couple of fresh crawlers (pinkish) in color.

For degree-day and phenology targets, look at:http://www.oardc.ohio-state.edu/gdd/

Notes:

I’m using the pine needle scale to illustrate our common armored scales. Remember that most armored scales are most susceptible to contact insecticides ONLY in the crawler and freshly settled crawler stages. These stages may only be susceptible for two to four week periods in the season, so knowing when crawlers are normally released is extremely important. When using systemic insecticides, the scales have to be feeding in order to pick up the material and be controlled.

I suggest that you look at our OSU-OARDC plant and pest phenology and degree-day web site at:

http://www.oardc.ohio-state.edu/gdd/

Many of the common scales are listed.

Scale Control (crawlers)

Traditional

• Diazinon

• Dursban

• Sevin

• Orthene

• Malathion

• Dimethoate (nursery)

• DiSyston (disulfoton)

Alternatives

• Tempo, Talstar, Deltagard, Scimitar, Astro

• Merit (soft scales)

• Flagship (nursery)

• Safari (armored & soft scales!)

• Arena & Aloft?

• Soaps & Oils

XX

Notes:

For traditional crawler sprays, most people use carbaryl (Sevin), acephate (Orthene), or one of the pyrethroids (often with 1.5 to 2.0% hort oil), or simply horticultural oils or insecticidal soaps. We still have the systemic dimethoate for use in nursery or Christmas tree production and home owners can still obtain Disyston granules which have systemic action against both soft and armored scales. When it comes to the neonicotinoids, almost all do a good job controlling soft scales, but only dinotefuran (Safari) has been consistently effective for control of armored scales. Safari will be most effective if applied near the time that crawlers have emerged and settled.

Emerald Ash Borer

EAB adult and D-shaped emergence hole.

Larvae look a bit like flat tapeworms!

More information? – http://ashalert.osu.edu

Notes:

The emerald ash borer continues to be spread across the country, primarily through human activities. Because of this wide-spread problem, State and Federal governments are only implementing quarantines when new areas are discovered to be infested. Infested trees are now the responsibility of the owners whether that be individuals (yards and wood lots) or municipalities (street trees, parks and other municipal properties). Some municipalities have adopted programs of ash removal and replacement but trees in individual’s properties are up to the owner to protect, remove and/or replace.

For more information on these issues as well as control recommendations go to: http://ashalert.osu.edu

Notes:

As one can see from this map, EAB has moved very rapidly into many surrounding states and Canada. This spread is likely to continue.

Borers – Agrilis species (bronze birch, twolined chestnut,

honeylocust, hornbeam, emerald ash borers)

Bronze birch borer

Notes:

With all the emphasis on EAB, we can’t loose site of the fact that we have many native species of Agrilis borers that are important in our landscapes! In fact, if you have been successful in controlling bronze birch borer, twolined chestnut borer, and honeylocust borer, you should be able to control EAB! It has a very similar life cycle and is susceptible to the same control materials.

Borers Continue – White Pine Weevil – white pine & SPRUCE

Notes:

The white pine weevil (which I call the “I’ll take the top out of almost any conifer weevil”) has continued to be a major problem in Ohio nurseries as well as landscapes where they kill the tops of white pine and spruces, primarily. This pest can be controlled in nurseries and Christmas tree plantations by spraying the tops of susceptible trees with dimethoate or Onyx or Astro in early April and again three weeks later. In landscapes, Onyx or Astro can also be used, but neonicotinoid soil injections or drenches are usually an easier and consistent treatment.

Borers Continue – Bark Beetles – mainly conifers

Notes:

Bark beetles continue to be problems in nursery and landscape conifers and deciduous trees across Ohio. Most of Ohio’s species are pests of stressed trees, so if an infestation is found, remove that tree quickly and inspect surrounding trees of the same species for signs of stress. Stressed trees can be protected with trunk bark sprays of Sevin, Onyx or Astro during the time that adult beetles are active, usually late May through June and again in August and September.

Borer Insecticides

Traditional

• Dursban

• Lindane

• DiSyston (disulfoton)

• Dimethoate (nursery)

• Bidrin injection

• Orthene injection

Alternatives

• Tempo, Talstar (Onyx), Deltagard, Scimitar, Astro

• Merit injection (beetles only!)

• Flagship? (nursery)

• Safari, Arena & Aloft, Meridian???

• TREE-age (injection only)

X

X

Notes:

As discussed under some of the borer groups, the best preventive insecticides (prophylactic treatments) are still Dursban (nurseries only), Onyx (and Onyx Pro), and Astro. These treatments will provide about 40 days of bark protection from borer invasion. Systemics that are effective preventives and early curatives are dimethoate (nurseries only), and the neonicotinoids (imidacloprid – Merit, clothianidin – Arena/Aloft, thiamethoxam – Meridian, and dinotefuran – Safari). Of these, clothianidin and dinotefuran may also have some clearwing borer (caterpillar borer) activity. Abamectin-benzoate (TREE-age) was registered in 2008 for EAB control by injection. This has been shown to be an effective treatment.

Honeylocust spider mites inhabit leaf undersurfaces.

Oak mites inhabit the upper leaf surface.

Maple spider mites – common on red and silver maples.

Warm-season spider mites

Notes:

We continue to see many species of spider mites attacking our landscape trees, shrubs and flowers. The warm-season mites, like oak, maple, linden, honeylocust, and twospotted spider mites, and our cool-season mite, the spruce spider mite, have been very common on their respective host plants. There have been very few resistance to miticides issues, but if you don’t get control, consider switching to a different miticide category and make sure you get thorough coverage of treated plants.

MiticidesTraditional

• Kelthane

• Morestan

• Dimethoate (nursery)

• Orthene ? (injection, drenches only)

Alternatives

• Avid (all mites!)

• Hexygon (eggs & larvae only, spider mites only)

• Floramite (spider mites only)

• Sanmite (spider mites only)

• Forbid (all mites!)

• Conserve

• Pyrethroids – NO!??

• Soaps or Oils

X

X

Notes:

We have some excellent miticides with Hexagon, Floramite and Sanmite being the most recognized names. Unfortunately, these miticides ONLY kill spider mites and we are seeing an increase in eriophyid (rust and gall) mites. Consider using Avid and/or Forbid/Judo as these two miticides will knock down all groups of mites, not just the spider mites.

Birch leafminer female laying egg.

Extensive leafminer damage can leave a tree looking as if it has leaf scorch.

Birch leafminer larva in mine.

Notes:

We continue to have the sawfly leafminers across Ohio, with the birch, hawthorn and elm leafminers being the most common pests. All of these have an early spring generation (birch can have several generations) which should be the target. Early applied neonicotinoids (or even mid-October into mid-November applications) have been effective in preventing these pests.

Elm fleaweevil adult

Elm fleaweevil larval mines

Notes:

Over the last two years, we have noticed that something was skeletonizing our landscape elms, especially some of the Serbian and new hybred elms. Upon closer look, it was found that the elm flea weevil is responsible for this. This weevil has larvae that produce a small blotch mine on the tips of elm leaves in May and June, but the adult weevils continue to skeletonize the foliage for the rest of the summer.

We have very little research on this pest, but field reports are indicating that Sevin or pyrethroid sprays will knock down the adults in the summer and neonicotinoid injections or drenches in the spring can eliminate the larvae and adults that feed on leaves.

Boxwood Leafminer

Notes:

The boxwood leafminer (a tiny midge) continues to damage many boxwood plantings across Ohio. The damage is often mistaken for winter desiccation or disease when the leaves turn yellow to orange in the spring and drop. Affected plants green up when the new buds break, but these are the leaves that will be infested by the larvae to repeat the defoliation the following spring.

Our neonicotinoid insecticides have been effective in controlling this pest when applied when the new buds break or in the fall. Fall applications also have the benefit of controlling the boxwood psyllid the following spring!

Leafminer Insecticides

Traditional

• Dursban

• Lindane

• Dimethoate (nursery)

• DiSyston

• Orthene

• Neem (azadirachtin)

Still/Now Available

• Pyrethroids (permethrin, resmethrin, esfenvalerate, bifenthrin, cyfluthrin)

• Merit, Flagship, Arena & Aloft, Safari

• Conserve ?

X

X

Notes:

As discussed under the previous common leafminers, the neonicotinoids appear to be the best products to use for our sawfly, beetle and midge leafminer pests. Fortunately, there are few caterpillar leafminers that are of concern in Ohio landscapes. Consider soil drenches or injections of the neonicotinoids in mid-October through mid-November to control leafminers that are active in May and early June.