When a plant is not doing well or gradually is going downhill, it takes a little detective work to find the true cause or causes. It could be that the soil is too acidic or too alkaline, or that salts have accumulated near the roots and need to be leached away with a deep, thorough watering; it could be that the plant cannot survive direct sunshine, or that the drainage is so poor that the roots are drowning from lack of oxygen; it could be that when the plant was bought, the roots were pot bound and have grown in on themselves, or that the plant species is not suited for the environment. This is why choosing plants that have been proven to thrive in your locality is so important.
The speed with which plant declines is a good clue. If it suddenly withers, then chances are it is one specific cause, possibly a pest or some form of root rot. If the plant declines over a period of time, chances are it is being stressed by the environment; usually there is more than one thing wrong.
Observation comes first. One day you notice that the leaves on your favorite plant are twisted and puckered. The first thing is to look for aphids, mites, or leaf rollers. To locate some pests, such as spider mites, and as an aid to seeing what is really wrong with a plant, you will need a magnifying glass. If you cannot see any insects, chances are the damage was done months earlier by trips-tiny insects that suck the juice from leaves. As the leaves grow, they become distorted around the wounds, but the leaves are otherwise functioning, so take no action.
If you assume the damage is caused by an insect and try to eliminate it. you could be wasting your time. More important, you
Clues to Plant Problems:
| LEAVES | POSSIBLE CAUSES |
| Green (normal shape, but undersized) | Insufficient water Lack of nitrogen Zinc deficiency Nematodes on roots |
| Green (normal shape, but wilting) | Insufficient water Root rot or nematodes Poor drainage, roots drowning Too much fertilizer Grubs attacking roots Exposure to chemicals |
| Yellow (normal shape) | Nitrogen deficiency Normal aging |
| All brown (normal shape) | Normal aging Frost damage Insufficient water Twig borers or cicada damage Root rot |
| Brown on edges only (normal shape) | Frost damage Salt buildup in soil Herbicide damage |
| Center of leaf brown (normal shape) | Sunburn damage |
| Pale color (new leaves have deep green veins) | Iron (deficiency) chloro-sis |
| Pale color (all leaves have deep green veins) | Soil too wet, poor drainage |
| New leaves mottled | Viral infection |
| Purplish color (normal shape) | Phosphorus deficiency Frost damage |
| Silvery look (normal shape) | Leaf hoppers |
| Bronze color (normal shape) | Red spider mites |
| Leaf edges chewed | Grasshoppers Beetles Birds Snails Crickets Caterpillars |
| Leaf edges ragged, torn | High wind damage |
| Leaf puckered | Mites Zinc deficiency |
| Semicircles cut in leaf | Leaf-cutting bees |
| Leaf chewed or gone, but stalks remain | Birds Rabbits Ants |
| All leaves gone | Rats Birds Rabbits Squirrels Ants |
| Many leaves suddenly on ground in normal growing season | Frost Drought Fertilizer burns Birds |
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