Insects of Woody Ornamentals

Transcription

1 Insects of Woody Ornamentals Slides Provided by Ruth O Neill MSU Entomologist

2 1. Wood boring Insects the larvae of beetles, moths, wood wasps

3 Aspen Borer, Saperda calcarata Quaking Aspen Cottonwood Poplar Round headed borers (cerambycid beetles) Larvae 2 5 years to mature Younger larvae feed underside bark Older larvae tunnel heartwood Tree not always killed, but susceptible to wind breakage

4 Aspen Borer, Saperda calcarata Quaking Aspen Cottonwood Poplar Plant densely and prune / remove stressed trees Keep trees fertilized and watered Kill large larvae with wire probe Adults: carbaryl, permethrin or an insect net

5 Mountain Pine Beetle, Dendroctonus ponderosae W Ponderosa Pine Lodgepole Pine Other Conifers Bark beetles make nests with radiating larval galleries under bark pitch tubes Feeding cuts off water and nutrients Blue stain fungi block resin response ~2 mm gallery entrance

6 Mountain Pine Beetle Occurs from Mexico to central B. C. New adults July end of summer Late emerging beetles from high elevations flyinto valleys At low populations, only weak trees attacked Controls: None once beetles are in! Pheromone patches Carbaryl or Permethrin drenches prior to egg laying

7 Western Ash Bark Beetle, Hylesinus californicus All Ash, Most Commonly Green Ash Branches, occasionally main stems Sawdust, sap flowing from wounds Ventilation holes often in rows Two armed galleries Generally weakened, stormdamaged, and felled trees Remove affected trees to prevent population build up Controls: water, fertilize, prune criss crossing branches

8 White Pine / Sitka Spruce Weevil, Pissodes strobi Adult overwinters in litter under tree Females puncture terminals, lay eggs Theyselect terminals > ½ Larvae tunnel through terminal Can kill top ~18 of leader Leader turns brown New adults emerge August, leave round holes Carbaryl to protect leader

9 Spruce Weevil shepherd s crooks pupal chamber

10 2. Galling Insects Often only a cosmetic issue Tolerance is important!

11 Eriophyid Mites Many trees, shrubs, other plants Greenhouse Pests 3600 spp. described (<10%) Microscopic carrotshaped Oftenmistaken for disease Most stimulate galls Some free roaming Foliage may bronze, rust, drop off Can kill plants

12 Eriophyid Blister Galls

13 Eriophyid Finger Galls

14 Eriophyid Erineum Galls Mats of Abnormal Leaf Hairs = Erinea

15 Eriophyid Erineum and Spindle Galls

16 Eriophyid Witch s Broom Hackberry witch s broom caused by eriophyid and/or powdery mildew

17 Oak Rough Bullet Gall Wasp Disholcaspis quercusmamma Bur Oak Photo: Ryon Stover Galls green in early summer, exude sugary sap Gall later brown, turn woody Can girdle / kill branches

18 Willow Redgall Sawfly Pontania proxima Willows Pupae overwinter in soil or debris Females emerge in spring, lay eggs on unfurling leaves Red bean shaped swellings Cosmetic issue only, leave alone or prune out

19 Poplar Vagabond Aphid, Mordwilkoja vagabunda Cottonwood Aspen Distorted leaf buds, aphids feed within Summer: Gallsplits splits, winged generation emerges Alternative host may be loosestrife Winged aphids return to old galls in fall Eggs overwinter in old galls Early Summer Lt Late summer, winter Mid summer Galls are hard to prune! They re in the upper 1/3 of the canopy

20 3. Other Plant Sap Feeders

21 Two Spotted Spider Mites, Tetranychus urticae Many Landscaping and Greenhouse Plants Pinpoint sized sap feeders 8 legged spider relatives Produce light webbing, bronzing, dessication Often mistaken for disease If using pesticide, must treat twith labeled lbldmiticide id Survey by shaking foliage over white paper

22 Oystershell Scale, Lepidosaphes ulmi Many Deciduous Trees and Woody Plants Cotoneasters especially! Bark cracked & scaly Foliage dwarfed, yellowed Dead branches; plant death Disfigured fruit eggs laid in fall Crawlers hatch late spring ~two generations / summer Crawlers: insecticidal soap Adults: Systemic only

23 Aphids, many species Aphids Piercing sucking mouthparts Stem mothers give live birth, populations expand quickly MANY natural enemies syrphid flies, lacewings, predatory plant bugs, spiders, parasitic wasps

24 but natural enemies can be kept away by ants. Ants of many species herd aphids for their honeydew.

25 Banding trees with Tanglefoot blocks aphid tending ants from access to canopy Use polyester to fill bark crevices and allow for trunk expansion during growth cover with tape or tree wrap, apply band of Tanglefoot Refresh surface of Tanglefoot band as needed

26 Some Ways to Suppress Aphids: Deny aphid herding ants access to crown Strong sprays of water on foliage Insecticidal soap Hand removal from smaller plants Insecticides but not usually needed

27 Currant Aphid, Cryptomyzus ribis Currant Gooseberry

28 Leafcurl Ash Aphid, Meliarhizophagus fraxinifolii Green Ash

29 4. Foliage Consumers

30 Cottonwood Leaf Beetle Cottonwoods Aspens Willows Adults overwinter in litter, eggs on undersides of leaves Larvae feed communally, several generations per year Skeletonized leaves; adults eat bark on seedlings as well On established trees, problem is mainly cosmetic

31 Poplar Blackmine Beetle, Zeugophora scutellaris Cottonwood Aspen Poplar Adults May July, skeletonize leaf undersides Eggs laid on skeletonized areas Larvae penetrate leaf and mine between layers Unattractive, but little impact on tree health Pupate in soil over winter

32 Questions?