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DEPARTMENT OF CONSERVATION
Maine Forest Service
Forest Health & Monitoring Division
Forest & Shade
Insect & Disease Conditions for Maine
Issue: April 22, 2005
Finally another interminably long winter is behind us and spring has officially arrived, marked by our first newsletter of the season. Welcome back!
We enter the field season of 2005 with yet another impending retirement. We are sad to report that Dick Bradbury will be leaving this week. Dick's departure will create a substantial void; his knowledge of entomology in general, and Christmas tree insects and browntail moth in particular, his extensive practical experience, and his great sense of humor will be sorely missed. Dick has been the senior author of this insect and disease conditions report for two years now, and we reluctantly press on without him. We wish him well as he retires to the good life of fishing, hunting, trapping, growing Christmas trees and managing his woodlots.
For the rest of us here, we anticipate an extraordinarily busy season as we attempt to provide a level of service comparable to past years with fewer workers. We will, however, need to enlist some assistance from you, our loyal stakeholders, in order to make this happen. In particular we need your eyes and ears, well eyes anyway, to make timely observations and to forward them to us. There are now simply too few of us left here to effectively keep up with insect and disease developments around the state as they occur. We recognize that many of our readers are capable of competently identifying a variety of forest and nursery insects, and are pretty good plant disease diagnosticians as well. So if you're willing to contribute, please send an email to firstname.lastname@example.org, indicating the sorts of problems you're willing to report (forest, Christmas tree, nursery, shade tree etc), and I'll respond with requests for observations during the course of the season.
While all of our staff are anxious to assist in any way possible, we have specialists to help with certain types of problems. Our State Entomologist, Dave Struble, makes policy for the division. Don Ouellette manages insect quarantine activity for the division, particularly hemlock woolly adelgid and pine shoot beetle, and performs insect identifications. Charlene Donahue oversees most of the forest insect survey work, serves as curator for the insect collection, and also performs insect identification work. Wayne Searles, Grayln Smith, and Mike Skinner serve as field technicians. Jean Maheux serves as our secretary/receptionist. Last, and probably least, Clark Granger manages the Entomology Lab, diagnoses tree diseases, oversees disease quarantines, responds to Christmas tree problems, and writes this newsletter.
We have attached the following items to this report for your use:
* Advice and technical assistance sheet.
* Insect Report Form for reporting insect problems.
* Disease Report Form for reporting diseases and unknown problems.
Have a Great Season!
IMPORTANT: Attached please find a mailing list sign up and renewal form (blue sheet). We are required to update mailing lists annually. Please complete and return this mailing list at your early convenience.
Our business hours for 2005 will be 7:30 a.m. to 4:00 p.m. Monday through Friday, except for holidays. However due to reductions in our work force, we may not be able to staff the I&DM Lab at all times. So if you call and receive no answer, please call back another time. And if you plan to visit the Lab, you may wish to call ahead just to to make sure someone will be present to meet with you.
Special Update on the Status of Pine Shoot Beetle by State Entomologist Dave Struble
The pine shoot beetle was first found in the United States in the Midwest in the early 1990's, having been introduced from Europe on pallet material. It spread eastward, reaching New Hampshire and Vermont by 1999, and was first found in Maine in Oxford County in 2000. Although it can survive on white pine, this exotic pest prefers Scotch pine and, to a lesser extent, other hard pines. Regional forest pest experts in northern New England do not consider pine shoot beetle to be a serious biological threat to local pine resources.
As of March 2005, in Maine only Oxford and Franklin Counties have been determined to have populations of this federally regulated pest. However, since last fall, all counties in both Vermont and New Hampshire have been designated for inclusion in the federally regulated area. This situation has threatened to cripple the ability of local mills in southern Maine to receive and stockpile raw white pine logs from regulated areas during the April 1 to June 30 shipping period (flight period for this insect). The potential impact of that situation was so severe that the state lobbied and successfully convinced USDA-APHIS to conduct a "Mini Pest Risk Assessment" to re-evaluate the risk associated with allowing import of regulated white pine during this formerly banned spring period. Although not yet published, the results of this assessment demonstrate that moving white pine logs from regulated areas of northern New England does not pose a significant increased risk of establishing PSB in currently uninfested areas of Maine.
Armed with these results, and working with Maine's pine using industry and the Congressional Delegation, we have been successful in obtaining approval for relaxing the complete embargo of movement of white pine logs from the regulated area. However, any mills or individuals who want to move pine logs from regulated areas (i.e. from Oxford and Franklin County, and/or anywhere in N.H. and Vt) will still be required to have "Permits" and/or "Compliance Agreements".
We are currently operating under a grace period while the MFS and APHIS develop specific compliance agreements for potentially affected mills and shippers. This grace period will expire within the next few weeks, at which time any shippers or receivers of regulated pine will be susceptible to federal inspection and subject to penalty for unauthorized movement.
If you are or are planning to ship or receive pine from the regulated area between now and July 1, call the IDM Lab [Don Ouellette] @ 287-2431. We will expedite issuance of necessary Compliance Agreements and/or Permits.
Arbor Week This Year is May 15-21
Arbor day in many states is celebrated on various dates in April with the last Friday in April (April 29th this season) being designated as National Arbor Day. As our season for tree planting is somewhat later than most other states, Maine has chosen to celebrate Arbor Week during the third full week in May which has proven to be better overall for tree planting and other outside activities.
Trees are some of our most important natural resources and Arbor Week is a good time to recognize their special importance in our lives. Consider not only the charm and aesthetics of our state tree, the eastern white pine, but also the functional and aesthetic value of some of the 65 other native and more than 30 exotic species found here.
Early Season Guide to Pest Management
The following table should assist you in the early season planning process. Remember that this is just a guide and that conditions will vary.
|Insect or Disease||Cultural Controls||Chemical Controls|
|Apple Scab||Remove any fallen leaves not raked last autumn; plant resistant crabapples such as 'Adams', 'Baskatong', 'Beverly', 'Bob White', 'David', 'Dolgo', 'Donald Wyman', 'Liset', 'Red Jewel' and 'Sugartyme'.||Propiconazole (Banner) or Thiophanate methyl (Cleary's 3336) or Chlorothalonil (Daconil, Ortho multi purpose fungicide) or Mancozeb (Dithane, Fore, Protect, Zyban) every ten days during wet weather.|
|*Balsam Gall Midge||Diazinon or chlorpyrifos (Lorsban) late May to early June.|
|*Balsam Shootboring Sawfly||Lorsban 4E or Diazinon AG500 3 times at 5 day intervals during the 2 weeks following the observation of activity of adults (mid-late April) or in the two weeks prior to normal balsam twig aphid spray dates.|
|*Balsam Twig Aphid||Diazinon or chlorpyrifos (Lorsban) at bud break.|
|*Birch Casebearer||Malathion or carbaryl (Sevin) applied after most or all of the cases have moved to opening buds.|
|Black Knot of peach, plum, and cherry||Prune and destroy knotted twigs and branches.||Thiophanate methyl (Cleary's 3336, Domain, or Fungo Flo) when dormant and twice again at three week intervals.|
|*Browntail Moth||Clipping of overwintering webs is only effective prior to the time larvae beginning actively feeding on emerging foliage (mid to late April).||The use of pesticides is a complex issue requiring professional assistance. Call for more information.|
|*Bruce Spanworm||Emerges early as buds begin to swell on northern hardwoods, especially beech. Larvae bore into buds. Controls not usually recommended.|
|Cyclaneusma Needle Cast of Scotch pine||Use disease free planting stock; remove non crop Scotch pines from area.||Chlorothalonil (Bravo) prior to bud break and during wet periods throughout growing season.|
|Dogwood Anthracnose||Remove any fallen leaves not raked last autumn; fertilize trees; prune out dead twigs and suckers; plant Chinese or Japanese dogwood instead of native flowering dogwood.||Chlorothalonil (Daconil 2787), or Thiophanate methyl (Cleary's 3336, Domain, Fungo Flo, Zyban) or Propiconazole (Banner) or Mancozeb (Dithane, Fore, Protect) at bud break and again three times at three week intervals.|
|Dutch Elm Disease||Plant disease resistant elms; eliminate all potential beetle breeding elm material within 700 feet of trees to be protected.||Dormant applications of methoxychlor or chlorpyrifos for beetle vector control if treatment appears on product label.|
|*Eastern Tent Caterpillar||Prune out egg masses on twigs prior to hatch; remove and destroy small tents as they develop (late April-early May)||Acephate, carbaryl (Sevin), cyfluthrin or Bt on warm days when larvae leave tents to feed.|
|*Fall Cankerworm||Acephate (Orthene), Bt., carbaryl (Sevin), cyfluthrin applied while larvae are small (late May-early June on boxelder in Aroostook County). Early to mid May on elm and oak in southern Maine.|
|*Gypsy Moth||Scrape egg clusters from tree boles and larger branches into a container and destroy them. Complete before egg hatch (late April).||Acephate (Orthene), Bt, carbaryl (Sevin), cyfluthrin, or diflubenzuron (Dimilin) when larvae are actively feeding (early June).|
|Hawthorn Leaf Spot
Mt. Ash Leaf Spot
|Remove any fallen leaves not raked last autumn; plant resistant sorts such as Crataegus crus-galli.||Thiophanate methyl (Cleary's 3336, Domain, Fungo Flo) or Chlorothalonil (Daconil) or Mancozeb (Dithane, Fore) as leaves unfold at two week intervals until dry weather.|
|*Hemlock Woolly Adelgid||Watch for signs of infestation and report immediately.||Call for information.|
|Horse Chestnut Leaf Blotch||Remove any fallen leaves not raked last autumn.||Thiophanate methyl (Cleary's 3336, Domain, Fungo Flo) or Chlorothalonil (Daconil 2787) at bud break and twice more at 14 day intervals.|
|*Larch Casebearer||Carbaryl (Sevin), or cyfluthrin (Tempo) applied after most cases have moved to the expanding needle clusters (late April to early May).|
|Maple Anthracnose||Remove any fallen leaves not raked last autumn.||Thiophanate methyl (Cleary's 3336, Domain, Fungo Flo) at bud break and twice again at 10-14 day intervals.|
|Peach Leaf Curl||Chlorothalonil (Bravo) or Ferbam (Carbamate) or Ziram (Triathlon) applied as full coverage spray when trees are dormant.|
|*Pear Thrips||Controls and timing not well understood. Thrips are active on expanding maple buds at which point much of the damage is done.|
|Pine-Pine Gall Rust of jack and Scotch pine||Prune rust galls from lightly infected trees; rogue heavily infected trees from plantations before May 1. Use disease free planting stock.||None at this time.|
|Rhabdocline Needle Cast
Swiss Needle Cast of Douglas Fir
|Rogue severely infected trees from plantations before May 1.||None at this time.|
|*Satin Moth||Tiny overwintering larvae move to expanding buds/foliage to feed by mid to late May. Treatment of infested poplars and willow should begin early with Bt, carbaryl (Sevin) or cyfluthrin.|
|Sphaeropsis Shoot Blight of two and three needle pines||Use disease free planting stock; remove non crop tree hard pines from area.||Chlorothalonil (Bravo) at bud break and when shoots are half grown.|
|*Spruce Gall Adelgids||Prune off and destroy new developing galls in mid to late June.||Treat infested trees just prior to bud break with carbaryl (Sevin) chlorpyrifos (Lorsban) or imidacloprid (Merit).|
|*Ticks||Watch for ticks throughout the field season (April-November). Avoid high risk areas if possible, inspect yourself daily and remove ticks and use repellents as directed.||Compounds containing DEET can be used as repellents. Those containing the toxicant permethrin can be used on clothing as directed.|
|*Viburnum Leaf Beetle||Where possible, prune off any twigs with scabby, egg-filled holes prior to May 1st.||Watch early (mid to late May) for developing larvae and treat with acephate (Orthene), carbaryl (Sevin), or chlorpyrifos (Lorsban).|
|*White Pine Blister Rust||Prune cankered lateral branches from trees and excise stem cankers by removing bark at least four inches above and below and two inches either side of discolored bark.||None at this time.|
|*White Pine Weevil||Refrain from planting white pine or spruce for reforestation in open areas, on heavy clay soils, or on heavily sodded fields. Correctively prune damaged trees to establish new leaders.||Commercial Forest and Christmas Tree Plantations: Dimilin before weevil activity commences. Licensed applicators who have stocks of Lindane on hand may apply for a limited use permit from the Board of Pesticide Control (287-2731).|
*Balsam Gall Midge (Paradiplosis tumifex) - Balsam gall midge populations have been light in recent years. Abundance of this species is cyclic and appears to be starting to rise. Christmas tree growers should watch for the small orange midges in mid to late May and be prepared to treat (late May to early June) as the new needles flare and begin to flatten. Use diazinon or chlorpyrifos.
*Balsam Shootboring Sawfly (Pleroneura brunneicornis) - Levels of this pest are expected to be down in 2005, but growers should remain vigilant just in case control is needed.
*Balsam Twig Aphid (Mindarus abietinus) - Populations are up in many parts of the state. If even light damage occurred within your Christmas tree production areas last year, treatment will likely be necessary this year.
*Birch Casebearer (Coleophora serratella) - Populations are very low in most areas. Look for the tiny "cigar" shaped larval cases at the base of the buds to determine if control is warranted.
*Browntail moth (Euproctis chrysorrhoea) - Browntail moth populations will be sufficiently high this year to plague landowners and recreationists along the coast from Portland to Woolwich. Inland towns likely to experience issues with this pest generally border the Androscoggin River from Brunswick and Topsham to Lewiston.
The intensity of the infestation varies much more this year than in the past and homeowners are encouraged to examine hardwood trees and shrubs on their property to determine if over wintering webs are present prior to making decisions regarding control. Generally if four or more webs are seen per host plant, population control is warranted. Removal and destruction of webs can eliminate the pest from sites having only low shrubs but sites with taller hosts such as oak trees will require the services of a licensed pesticide applicator. Clipping should be completed by the end of April and insecticide applications should be made during the month of May.
*Forest Tent Caterpillar ( Malacosoma disstria ) - Light trap catches for forest tent caterpillar moths increased in 2004 and one area of defoliated mixed hardwoods was reported from Penobscot County. The population of this forest defoliator may be on the rise and bears watching. A minor forest tent caterpillar outbreak occured in the early 90's and a larger outbreak took place in northern Maine in the early 80's. Larvae emerge in early spring and feed on poplar, oak and other hardwoods. They do not make tents but may be found feeding on leaves in conjunction with eastern tent caterpillars and gypsy moths.
*Hemlock Looper ( Lambdina fiscellaria ) - Hemlock looper has been at endemic levels for a number of years. New Brunswick saw an increase in moth catches of this insect in 2004 and Quebec had a couple of areas with moderate defoliation. This insect has the potential to damage hemlock and other conifer stands when populations increase. In Maine there were no reports of either damage or large numbers of moths flying last September but since insects do not respect international boundaries, be on the lookout this year for feeding on softwoods. Larvae begin feeding in early June, first on new foliage then move to older needles.
*Hemlock Woolly Adelgid (Adelges tsugae) - Hemlock woolly adelgid (HWA) was first located in Maine in the wild on native hemlocks on Gerrish Island in Kittery in 2003. It has now been found in a total of three towns in southern York County.
Maine's HWA quarantine will soon be expanded to include the towns of Kittery, York, and Wells. This new, expanded quarantine will restrict the movement of nursery stock and logs from infested towns. The present HWA quarantine only restricts the importation of nursery stock and logs from infested areas into Maine, and will remain in effect until the new quarantine becomes legally finalized.
A recent change in New Hampshire's HWA quarantine will have an impact on shippers who move hemlock logs from quarantined areas in York County into New Hampshire. Under the new rules shipments of hemlock logs, lumber with bark attached, chips with bark attached and uncomposted hemlock bark can only go to pre-approved sites operating under a compliance agreement in NH and/or must be accompanied by a phytosanitary certificate or certificate of origin issued by the state where the hemlock originates.
If there is any good news about HWA, it is that no new infestations were found on outplanted nursery stock in Maine in 2004.
*White Pine Weevil (Pissodes strobi) - After wintering in the soil, the adults of the white pine weevil are now ascending host trees (white pine and spruce). Pitch flow from feeding punctures at the base of the terminal buds is the most obvious early sign of weevil movement but careful observation will reveal the reddish-brown weevils hiding between the needles and buds. When nestled in the buds they resemble buds. Diflubenzuron (Dimilin) and lindane will provide effective weevil control but are restricted and can only be used by licensed applicators. Each of these products has qualities which applicators should be aware of. Dimilin must be applied early to give the highest efficacy. To use lindane a special permit must be obtained from the Maine Board of Pesticides Control, Department of Agriculture, 28 State House Station, Augusta, Maine 04333-0022.
Diseases and Injuries
Rhizosphaera Needle Cast (caused by Rhizosphaera kalkhoffii) - Two consecutive moist springs seem to have provided ideal conditions for buildup of Rhizosphaera needlecast infection on spruce, especially in landscape situations. We have received calls from many homeowners who report thinning of the lower crowns of their spruce trees, especially Colorado blue spruce. Most frequently affected are border plantings of larger blue spruce, where trees provide a screen between abutting properties, but solitary trees may be affected as well. The thinning lower crowns on the border trees have the potential to compromise their function of providing privacy screens.
While it is possible to spray for control of this disease in the landscape, it is not often done. For effective control, at least two sprays are required (at half needle elongation and again when needles are fully elongated), and affected trees are often so large and numerous that chemical control efforts are discouraged.
Rather than spray, many homeowners will opt for resistant sorts (Norway spruce is among those exhibiting resistance) or the screening effect of a thinning blue spruce border planting may be reinforced by planting another evergreen hedge (not spruce) in front of the infected border trees.
For those who do wish to spray, chlorothalonil alone, or in combination with other fungicides, is effective.
Salt Damage (caused by movement of deicing salts from road surfaces to susceptible plant species) - Symptoms of salt damage to roadside vegetation were considerably more conspicuous than usual during the past winter season. Heavy snows throughout the winter (the inevitable result of an active El Nino weather pattern which set up in the Pacific Ocean) prompted the use of large quantities of deicing salts and resulted in considerable damage to roadside conifers.
The damge as usual was of two types: (1) foliage browning, especially of white pine growing very closely to travelled road surfaces, the result of direct salt deposition on foliage due to the action of passing traffic and (2) foliage browning of fir, hemlock and white pine, growing at greater distances from travelled road surfaces, but sited where root systems could take up pooled, salty water.
Most but not all affected trees will recover as the season progresses, with new green growth masking the presently brown needles, many of which will fall prematurely as the season progresses.
Winter Injury - Every winter season brings damage to nursery and landscape trees through snow and ice breakage, cold temperatures, and winter dessication. Often these effects are immediately apparent as winter browning and broken stems, but often damage doesn't become conspicuous until flower buds don't break into bloom or worse, no buds break at all because a plant has died overwinter. We don't have a good handle yet on winter damage and solicit your assistance as we progress into spring. Your reports, forwarded to me at email@example.com would be most appreciated, especially from the nursery and landscape community.
If you have recently planted tender landscape stock, especially exotic sorts, and have noted some winter damage, take heart. For many species, hardiness increases with age, and winter injury may diminish over the years as your plants mature.
Compiled by Clark A. Granger
01/05 Forest Health & Monitoring Division Augusta, Maine