Tree Insects in the Forest and Urban Landscape Christine Buhl, ODF Entomologist Eugene MG

Transcription

1 Tree Insects in the Forest and Urban Landscape Christine Buhl, ODF Entomologist Eugene MG

2 Trees are stressed by Inappropriate climate, location, etc. for the species (offsite) Poor site quality Drought and other weather/climate stress Fire damage Competition Old age Mechanical injury Soil compaction Disease Defoliation and other insect damage TREE STRESS = INSECT INFESTATIONS

3 Avoid/Mitigate damage Plant native, site-appropriate species and cultivars Avoid mechanical damage (mowers) Water slowly and deeply to penetrate roots (drip irrigation) Irrigate consistently to prevent roots from moving to the surface Do not alter drainage patterns near established trees Avoid burning near trees Avoid chemical damage (herbicide drift or runoff) Avoid over-fertilization or fertilization during droughts Avoid soil compaction (driveways, walkways) Destroy infested trees and slash to prevent bark beetle outbreaks Promote natural enemies by reducing broad-spectrum pesticides and drift

4 Drought Impacts: Scattered flagging/dieback at terminals (furthest extent that water has to travel) Roots move to the surface to reach precipitation, increasing exposure to compaction Increased susceptibility to bark beetles, cankers and other pathogens

5 Drought tolerance of tree species in the Willamette Valley Tree Species Drought Tolerance* Oregon white oak 1 Valley pine 1 Incense-cedar 2 Douglas-fir 3 Grand fir 4 Western redcedar 4 *Tolerance rating: 1 = High; 5 = Low

6 Climate change: what does it mean for us? Reduced precipitation, soil-water, groundwater and reservoir Higher temperatures Altered phenology (e.g., early spring, extended summer)

7 Climate change: what does it mean for plants? Altered evapotranspiration and gas exchange Reduced sap flow as a chemical defense Increased wildfire risk

8 Climate change: what does it mean for insects? Altered synchrony (mismatched hatch and host plant development) Reduced flower and nectar production More generations possible Population outbreaks Altered range distribution Collapse of trophic level systems

9 Insect guilds Wood-infesting Bark beetles Wood boring beetles, caterpillars and wasps Defoliators Caterpillars, sawflies, leaf beetles Sap-feeding Scales, gall insects, aphids, adelgids

10 Bark beetles Most at risk Stressed trees, trees near slash Biology Adults create brood galleries on inner bark and larvae and adults feed on phloem/cambium which girdles tissues. They also vector cell-clogging fungi. Damage Reduced tree growth, mortality Introduction of fungus hastens mortality

11 *secondary pest Major bark beetles in Oregon Forests Douglas-fir Doug-fir beetle True fir Fir engraver* Pine Ips spp. beetles Mountain pine beetle Western pine beetle (ponderosa only)

12 Bark beetle signs & symptoms Pitch streams and tubes Frass Galleries Stains Woodpecker damage

13 Bark beetle management Maintain tree vigor, reduce damage and competition, manage densities Remove infested trees Manage slash Insecticide bole sprays (expensive, labor intensive) Insecticide systemic (unproven efficacy) Pheromones (mixed efficacy) *Only preventative not curative* Once beetles are in trees they cannot be killed unless trees are destroyed

14 Wood borers: Ambrosia beetles Most at risk Various hard and softwoods, felled or standing dead trees, wet or coastal regions and timber lots Damage Fine white frass, pinholes, black staining *Feeds on fungal ambrosia gardens not wood Management Process felled logs quickly, keep logs wet to reduce fungal growth

15 Wood borers: Round and Flathead Flatheads/Metallic borers Horseshoe nail-shaped larvae Bullet-shaped adults, often metallic, with short antennae Packed, concentric frass D-shaped exit holes Roundheads/longhorned borers Cylindrical larvae Long antennae on adults Slivered frass Round exit holes *Most species are the cleanup crew that assists decomposition following damage caused by primary agents

16 Flathead of *concern: Flatheaded fir borer Most at risk Doug-fir growing on poor sites at <3,500, thin or serpentine soils, drought and fire stress Management Switch to or interplant Valley pine

17 Flathead of *concern: Bronze birch borer Most at risk European & Asian birch varieties, overexposure to sun Damage Branch dieback starting at top of tree Management Prune out dieback early

18 INVASIVE! Emerald ash borer SIGNS: D-shaped holes or dead branches in ash Report find: INVADER More info:

19 INVASIVE! Asian longhorned beetle Round holes and chewed niches in various hardwoods Report find: INVADER More info:

20 Wood borers: Carpenterworm Biology Females moths often attack previously infested hardwoods (and don t fly far from emergence spots), gallery entrances near crotches and bark crevices and drop vertically. Damage Dark sap spots on trunk, frass, weakens limbs Management Irrigate, remove infested branches, skewer larvae in tunnels, apply nematodes to tunnels and plug entrances

21 Wood borers: Pitch moths Most at risk Pines and Doug-fir with pruning wounds, previously infested trees Damage Mostly aesthetic. Can cause breakage on small trees. Mature trees may suffer growth loss. Management Prune only late fall-winter, manually remove pitch masses to reduce re-infestation

22 Wood borers: Woodwasps Most at risk Trees growing on poor or non-productive sites Biology Adult females inject toxic mucus and a fungal symbiont along with eggs to pre-digest wood for their young Signs Round exit holes, tip dieback/flagging

23 Sap-feeding: Black pineleaf scale Most at risk Pine, Doug-fir, spruce on droughted, dusty or scabby sites; sites near agriculture or vector control spray areas Damage Chlorotic spots, 2 nd year needle loss/lion s tail, branch dieback, bark beetle secondary attacks Management Avoid pesticide drift, promote natural enemy habitat, treat with systemic - timing is important! Lion s tail

24 Sap-feeding: Gall insects Most at risk Common on Oregon white oak Damage Mostly damaging for small oaks due to girdling Can trigger debarking by squirrels Management None advised, trees can often withstand

25 Defoliators: Leaf beetles Preferred Alder, elm, willow, cottonwood, etc. Damage Lacey skeletonization of leaves Management None advised, leaf beetle populations often fluctuate and trees reflush after damage

26 Defoliators: Moth & Butterfly caterpillars Most at risk Conifers due to inability to annually reflush all leaves Damage Repeated loss of photosynthate can cause some growth loss in deciduous trees, a single outbreak can kill conifers Management Bt and spinosad are very effective but outbreaks will collapse on their own due to disease and natural enemies

27 Defoliators: Sawflies Most at risk Conifers due to inability to annually reflush all leaves Damage Repeated loss of photosynthate can cause some growth loss in deciduous trees, a single outbreak can kill conifers. Often stubs of needles are left. Management None advised, often trees rebound; contact pesticides risks to natural enemies

28 INVASIVE! Gypsy moth Attacks over 300 spp. of hardwoods and some conifers Report find: INVADER More info:

29 INVASIVE! Gypsy moth: ID

30 Resources ODF Forest Health fact sheets: USFS Forest Insect and Disease Leaflets (FIDLs): OSU PNW Extension insect guides: OSU Forestry Extension: ODF Stewardship Foresters:

31 Questions?