Signs and Symptoms

Fungi

• Wilting

• Fruiting structures, such as rust or molds

• Dampening off

• Leaf spots

• Chlorosis

Bacteria

• Canker

• Crown gall

• Angular spots between veins

• Water soaked lesions

• Leaf spot with yellow halo

• Wilting, die back, yellowing, or browning

• Oozing, including in stem, leaf, or petiole

Virus*

• Foliage is mottled, ridged, or uniform

• Stunted growth

• Distorted growth, puckering, witches brooms

*Please note: virus symptoms can easily be confused with abiotic problems, such as herbicide damage or an insect feeding injury.

Chewing Insects

Entire midrib consumed, mid-blade may remain

• • sawfly larvae

  • caterpillars

  • canker worms

  • web worms

Randomly scattered holes in leaves

• • chafers

  • beetles

  • weevils

  • grasshoppers

Skeletonized leaf surfaces

• • Japanese beetles

  • sawfly larvae

  • thrips

Translucent or separated leaf surfaces

• • leaf miners

Girdling or holes in bark or stem tissue

• • borers

Root feeding

• • beetle, beetle larvae

Sucking Insects

Spotting or stippling

• • aphids

  • plant bugs

  • spider mites

  • whiteflies

  • mealy bugs

  • scale

  • leafhoppers

Galls and swellings

• • adelgids

  • eriophyid mites

  • wasps

Slime trails or holes in leaves

• • slugs and snails

Chewed bark on small trees/shrubs

• • rodents and small mammals

Branches torn or clean cut

• • rabbits (look for an angle cut on stem)

  • deer (look for shredded tops on stems)

  • squirrels (will knock small branches out of canopy)

Holes on tree trunks

• • sapsucker (evenly spaced across tree trunks)

  • woodpecker (random patterns)

Mechanical Damage

• Lawn mower, weed whip (damage to tree trunks)

• Tree planted too deeply (straight trunk, girdling roots)

• Construction damage (decline in plant canopies due to obstruction of roots)

• Hail/wind storm (shredding of leaves, branch loss)

• Salt damage (stunted growth or plant decline, brown damage from salt spray on conifers)

• Transplant shock (wilting)

Environmental Factors

• Heat (leaf damage occurs on most exposed portion of the plant)

• Cold (branch tip dieback, leaf disortion)

• Frost (cracks in trunk, browned needles in conifers)

• Sun damage (scorching, bleaching of leaves and fruit)

• Water (too little or too much may cause wilting)

• Oxygen (lack of oxygen in the root zone may cause plant decline)

• Nutrition deficiency (chlorosis)

Chemical Factors*

• Pesticide use or misuse

• Herbicide drift (leaf wilting, distortion, cupping)

• Nutrition deficiency or toxicity (discoloration or chlorosis common)

*Pattern of injury will vary, and may include spotting or necrosis on leaf edges, curling or cupping of leaves, and stunted growth.