How to Tell Pest Damage from Disease
Before treating a sick-looking plant, figure out what kind of problem you are dealing with.
Insects, diseases, weather, and nutrient problems can create very different symptoms.
Pest Damage Often Looks Like
- Chewed holes
- Missing leaf edges
- Skeletonized leaves
- Tunnels
- Sticky honeydew
- Webbing
- Frass
- Punctured fruit
Disease Often Looks Like
- Spots
- Lesions
- Mold
- Mildew
- Rot
- Cankers
- Vein discoloration
- Progressive yellowing or browning
Nutrient Problems Often Follow Patterns
Nutrient deficiency may cause:
- Uniform yellowing
- Interveinal chlorosis
- Stunted growth
The pattern may appear first on old or new leaves depending on the nutrient.
Water Stress Can Mimic Disease
Both drought and saturated roots can cause wilting.
Always check soil moisture.
Inspect the Whole Plant
Look at:
- New growth
- Old leaves
- Stems
- Roots
- Fruit
- Soil line
Look for Living Evidence
Check for:
- Insects
- Eggs
- Droppings
- Webbing
- Larvae
If no pest is present, consider disease or environmental stress.
Distribution Matters
If one plant is affected, think:
- Local injury
- Root damage
- Individual disease
If every plant in a bed is affected, think:
- Water
- Fertilizer
- Weather
- Herbicide
- Soil conditions
GardenGrowz Tip
Do not choose a treatment until you know which category of problem you are treating.