Major Symptoms & Possible Causes
Sometimes the cause of a garden problem is easy to identify. Fan shaped mounds of soil littering a lawn are obviously the work of a pocket gopher; slime trials leading to plants with large, ragged holes in the leaves can only mean slugs or snails.
A bigger challenge is deducing the source of trouble when many explanations are possible. Leaf yellowing and wilting, for example, may be due to insects, nematodes, diseases, or improper watering. If you can’t find clear evidence of a pest, the best course is to assume that growing conditions are at fault, then to focus on improving them. If you’re convinced a pest or disease is the villain, check the rogues’ gallery for a likely candidate but be sure all the evidence fits before placing blame.
Your Disease and Pest Control Experts
For help in solving problems you can’t identify on your own, consult your Cooperative Extension office or a reputable local nursery.
| Symptoms | Possible Causes | Notes |
|---|---|---|
| Leaf yellowing | Spider mites Insects Nematodes Root rot diseases Viral diseases Over watering Nutrient deficiencies Soil chemistry Old age | Usually pinpoint yellowing Especially bark borers Wilting also occurs Older leaves affected firstOlder leaves affect first |
| Leaf mottling | Viral diseases Pesticide damage Natural on some plants | Genetic variegation |
| Leaf spots | DiseasesInsects Spider mites Air pollution Pesticide damage Nutrient deficiencies Soil chemistry | |
| Leaf malformations | Sucking pests Viral diseases Peach leaf curl Lack of water Nutrient deficiencies Pesticide damage | On peaches and nectarinesEspecially from certain weed killers |
| Holes in leaves | Chewing pests Birds | |
| Leaf drop | Diseases Bark borers Improper watering Improper light Air pollution Nitrogen deficiency Soil chemistry Natural on some plants | Deciduous plants |
| Cankers(sunken lesions) | DiseasesInsects Root stress Sunburn Mechanical wounds | Especially borersFrom lawn mowers, pruner, and other equipment |
| Branch dieback | DiseasesInsectsNematodes Root stress Soil chemistry | Especially vascular diseases such as firelight and verticillium wilt Severe infestation by root or foliar pests or twig girdlers |
| Root rot | Diseases Over watering Root stress Soil chemistry | Usually fungal |
| Discolored tissue inside roots and stem | Wilt diseases Fertilizer damage | |
| Root malformations | Nematodes Diseases Girdled roots Natural on some plants | Crown gall, for example Formed in container Nitrogen-fixing nodules on legumes |
| Poor germination | Old Seeds Uneven irrigation Incorrect planting depth Damping-off disease Soil crusting Insects Birds | Root maggots, wireworms |
| Wilting | Lack of water Insects Nematodes Diseases | Especially borers and root feedersRoot rots and wilt diseases |
Bonide Products
Bayer Products
Fertilome Products
Pest Control
