The best defense against insects and diseases is to maintain a healthy tree with proper watering, proper pruning, and protecting the bark from weed-whip and lawnmower damage.

Common Insects and Diseases in Southeastern Colorado

For detailed information about maintaining healthy trees in southeastern Colorado, please read Tips for Healthy Trees – Updated August 2010 (384 KB PDF).

For more tree care information, look under Arboriculture on our Community Forestry web page.

Many of the insects and diseases listed can be found on the Colorado State University Extension website.

Tree Species Family

CSU Extension
In Action Fact Sheet #

Ash
Ash Bark Beetle
Banded-ash clearwing borer 5.530, 1425 (Plant Talk)
Brownheaded ash sawfly 5.586
Carpenterworm borer 5.530
Cytospora canker 2.937
Lilac/ash borer 5.530, 1425 (Plant Talk)
Sunscald 2111 (Plant Talk)
Improper watering (typically under) 2.926, 7.211
Cottonwood: Native plains, hybrid cottonless)
Aphids 5.511
Bacterial wetwood 2.910
Carpenterworm borer 5.530
Cottonwood borer 5.530
Cytospora canker 2.937
Fall webworm 5.583
Petiolegall aphid 5.557
Poplar borer 5.530
Poplar twiggall fly 5.597
Improper watering (typically under) 2.926, 7.211
Elms: Siberian, American, English
Bacterial wetwood 2.910
Banded elm bark beetle
Carpenter worm borer 5.530
Cytospora Canker 2.937
Dutch elm disease (transmitted by the lesser European bark beetle) 5.506
Elm leaf beetles 5.521
European elm scale (and associated sooty mold)
Fruits, pome (crabapple, apple, pear) 5.519, 2.800
Cytospora canker 2.937
Flatheaded apple tree borer 5.530
Fireblight 2.907
Shothole borer 5.520
Sunscald 2111 (Plant Talk)
Improper watering (typically under) 2.926, 7.211
Fruits, stone (cherry, plum, peach, apricot, etc.) 5.520
Apple flea beetles 5.592
Cytospora canker 2.937
Peach tree borer 5.566
Shothole borer 5.520
Sunscald 2111 (Plant Talk)
Improper watering (typically under) 2.926, 7.211
Hackberry
Apricot scale
Hackberry nipple gall 5.557
Juniper (Eastern Red Cedar/Rocky Mountain Juniper)
Flatheaded wood borer 5.530
Fletcher scale 5.514
Juniper-hawthorn rust 2.904
Spider mites 5.507, 5.569
Western cedar bark beetle
Winter desiccation 2105 (Plant Talk)
Locust, black
Locust borer 5.530
Locust, honey 2.939, 5.571
Cankers 2.939
Honeylocust spider mite 5.571
Sunscald 2111 (Plant Talk)
Improper watering (varies between over and under) 2.926, 7.211
Maple
Carpenterworm borer 5.530
Girdling roots
Leaf scorch
Iron chlorosis 2.928
Improper watering (typically under) 2.926, 7.211
Pine, piñon 2.948
Ips bark beetle 5.558
Piñon pitchmass borer 5.530
Piñon sawfly 2.948
Piñon tip moth 5.529
Piñon twig borer 2.948
Improper watering (typically over with too frequent/shallow applications) 2.926, 7.211
Pine, ponderosa
Spider mites 5.507, 5.569
Western pine tip moth 5.529
Winter desiccation 2105 (Plant Talk)
Improper watering (typically under or too frequent/shallow applications) 2.926, 7.211
Walnut, black
Thousand cankers disease Pest Alert, Q&As