Beans problems
Beans are mostly troubled by rust and by bacterial blights that spread fast in wet weather — which is why you should never work among wet bean plants.
Start from what you can see
Each of these has more than one possible cause, and each page separates them.
Everything that commonly affects bean plants
Most serious first. Most of the list is treatable or can be ignored.
Growing conditions
Only new growth is affected; older leaves are untouched.
Virus
Light and dark green mottling with soft, blurred boundaries.
Pest
Fine even stippling rather than discrete spots or holes.
Fungal disease
Sunken circular lesions on ripe fruit that deepen over days.
Pest
Dense clusters on new shoots and flower buds rather than scattered individuals.
Bacterial disease
Greasy, water-soaked appearance, especially in the morning.
Pest
Leaves reduced to a lace of veins rather than holed or notched.
Nutrient problem
Whole leaf yellows evenly, veins included.
Fungal disease
Orange powder that rubs off onto a finger or a white tissue.
Growing conditions
Leaves dry and crisp rather than soft and limp.
Check these two things first
- Push a finger into the soil, two knuckles deep. Wet soil plus a wilting plant means too much water, not too little — and it is the commonest reason a plant is dying. Dry soil plus crisp leaves means the opposite. The leaves look nearly identical either way, so the soil is what tells you.
- Turn a damaged leaf over. Half of all diagnoses live on the underside: fuzz means downy mildew, fine webbing means spider mites, clusters of insects mean aphids. Nothing on the top of a leaf is as informative.
Most garden problems are cosmetic and resolve without treatment. Reach for a spray last, not first.
Diagnose your beans
Already filtered to bean plants. Add the symptoms and where the trouble started.
1.What plant is it?
Many problems are specific to one family, so this removes a large share of the list straight away.
2.What does it look like?
optionalPick everything you can see. Any one match keeps a cause on the list, because you rarely see the whole picture at once.
3.Which part is affected?
optionalIf the roots are involved you will have to unpot or dig to find out — and with a declining plant that is usually the most informative thing you can do.
4.Where did it start?
optionalThe most underused question in plant diagnosis. Trouble that begins at the bottom means something very different from trouble that begins at the top.
- Herbicide DamageAct nowGrowing conditions
- Mosaic VirusAct nowVirus
- Spider MitesAct nowPest
- AnthracnoseTreatableFungal disease
- AphidsTreatablePest
- Bacterial Leaf SpotTreatableBacterial disease
- Japanese BeetlesTreatablePest
- Nitrogen DeficiencyTreatableNutrient problem
- RustTreatableFungal disease
- UnderwateringTreatableGrowing conditions