Three Categories of Plant Problems
Common Plant Problems
UI Publications on Plant Problems
Why Prune?
When to Prune?
Two Basic Types of Pruning Cuts
Location of Pruning Cuts
Pruning Tools
More Information
Time of Year to Plant
Special Planting Needs
Planting Instructions
More Information
Instruction for Specific Plants
Why Fertilize Landscape Trees
Soil Types
Diagnosing Nutrient Problems
When to Fertilize
Determining Fertilizer Quantities
More Information
Insects
Diseases
Physiological
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Diagnosing Plant Problems
Three Categories of Plant Problems
1) Insects - may include chewing or boring into leaves and stems, or plant parts missing altogether. Leaves may be curled, skeletonized (only the leaf veins remain while the tissue between the veins is missing) or have dead spots from insect feeding. Insects may also spread bacterial, fungal, or viral diseases from plant to plant.
2) Pathogens (diseases) - includes viruses, bacteria and fungi. Leaves may have circular or irregular patterns of dead or discolored tissue or be completely covered in spores from fungi.
3) Non-infectious (physiological) - includes nutrient deficiencies and toxicities, environmental stresses, or damage caused by chemicals, animals,
weather or equipment
Five Steps to Complete When Diagnosing Plant Problems
1) Identify the plants species and cultivar if applicable - Determine if growth is normal? Did the plant grow
abnormally this year, or did it grow at all? What is the leaf shape and size
compared to ideal?
2) Look for patterns - Are other plants in the area affected too? Are the symptoms uniform or random? Is more than one species affected?
3) Determine what part(s) of the plant are affected - Are the roots, stem, leaves or branches affected? How has the damage progressed over time?
4) Look for visible symptoms (abnormal appearances or characteristics of plants) and signs (indirect or direct evidence of a pathogen or insect) - chlorotic (yellowing of plant foliage), necrotic (browning and death of plant foliage), contorted growth, damaged or missing parts. What are the leaf patterns and color? Are any signs of the insect or disease (visible insect body parts or fungus spores) present?
5) What are the environmental and cultural situations present? Ask questions about management practices (watering and fertilizing), history of the area, weather, soil, and handling of the plant. Find out the current history of the area where the plants are growing.
What fertilizers or pesticides have been used? What is the irrigation system
and how much/how little water has been applied and when?
Common Plant Problems
| Plant stunted, weak growth, leaves off color or limbs dying |
Powdery mildew (white powdery fungus on leaves), rusts (red, black or orange spots on leaves), leaf spot (black spots on leaves |
borer damage to stem or leaves, look for holes in stems or leaves |
Poor soil drainage, drought damage, excess soil drainage, planting too deeply, improper soil pH, cold damage, lawn mower damage, sunscald, stem breakage, animal damage |
Consider working organic matter into soil before planting shrubs or trees to help improve soil aeration and water-holding capacity.
Lack of water is the primary cause of death to recently transplanted shrubs and trees |
| Plants dying suddenly |
Root rots (fungus) |
Insect larva attacking roots |
Over fertilizing, severe drought damage, poor soil preparation |
When root rot damage is moderate, symptoms may be similar to those of drought damage |
| Yellowing (chlorosis) |
Viruses may cause a mottled appearance on the leaves |
Insect damage to stem or stippling of leaves |
Nutritional deficiency (N, Zn or Fe), poorly drained soil, over fertilization, mechanical damage to stem |
N deficiencies occur on lower leaves first and move up the plant. Fe deficiencies result in interveinal chlorosis of the upper leaves first. |
| Browning of margin or edges of leaves |
Root rot (fungus) |
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Frost or cold damage, drought damage, transplanting shock, poor soil drainage, excessive fertilization, mechanical damage |
Frost damage usually occurs in early spring as buds leaf out. Damage may not be visible for a month or more. |
| Plant fails to flower |
Bud blight and other fungal diseases of the flowers |
Aphids, thrips, grasshoppers, and other chewing or sucking insects |
Plant is too young or excessive vegetative growth over shading |
High N levels in soils and ideal growing conditions may delay flowering of some plants. |
| Plant fails to produce berries |
Fungal diseases at flowering |
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Cold or frost during flowering, plant is a male or a male plant is missing with only female plants present, improper pruning |
Using hedge shears to prune shrubs usually results in the removal of most of the tip growth and future flower buds. Berry-producing plants are best pruned by removal of individual limbs inside the plant. |
| Loss of berries before maturity |
Fungus disease on berries |
insect larva |
Drought damage |
In mild to moderate attacks by floral diseases, the berries may be discolored or deformed. |
Taken from: Perennial Ornamental Plants. H.S. Fenwick, Extension Plant Pathologist. University of Idaho College of Agriculture. Current information Series 146, 1977.
UI Publications On Plant Problems
Encouraging Beneficial Insects in Your Garden
2001 PNW 550 Price: $1.00 (available in hardcopy only)
Honeysuckle Witches' Broom Aphid
1992 CIS 956 Price: $0.75 (available in hardcopy only)
Locust Borer, The
1988 CIS 829 Price: $0.25 (available in hardcopy only)
Bacterial Wetwood and Slime Flux of Trees
1990 CIS 876 Price: $0.25 (available in hardcopy only)
Cytospora Canker Disease in Idaho Orchards
1984 CIS 726 Price: $0.25 (available in hardcopy only)
Diplodia Tip Blight on Ponderosa Pine
1992 CIS 946 Price: $0.50 (available in hardcopy only)
Phytophthora Collar-Rot of Orchard Trees
1985 CIS 752 Price: $0.50 (available in hardcopy only)
Management of
White Pine Weevil in Spruce
2006 CIS 1133 (online version available)
Controlling Iron Deficiency in Plants in Idaho
1996 CIS 1042 Price: $2.00 (online version available)
Controlling Sunscald on Trees and Shrubs
1990 CIS 869 Price: $0.25
Leaf Scorch of Broadleaf Shade Trees
1974 CIS 238 Price: $0.35
Nutrient Disorders in Tree Fruits
PNW 121 (online version available)
Why Is My Evergreen Brown?
1970 EXT 514 Price: $0.50
Why Home Fruit Trees Die
1986 CIS 776 Price: $0.25
University of Illinois Articles on Specific Topics
Ohio State University Articles on Specific Topics
Other University Resources
University of Minnesota
http://www.extension.umn.edu/topics.html?topic=5&subtopic=166
Ohio State University
hcs.osu.edu/plantfacts/pest/
plantfacts.osu.edu/faq/
http://extension.osu.edu/lawn_and_garden/plant_diseases.php
http://ohioline.osu.edu/hyg-fact/3000/3304.html
http://ohioline.osu.edu/b614/index.html
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