Squash & Zucchini wilting
There are 6 common causes, and they need completely different responses — so working out which one you have matters more than treating quickly.
4 of them can kill the plant. Rule those out first.
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.
The 6 causes, and how to tell them apart
1.Bacterial Wilt
Act nowBacterial disease
Individual leaves wilt suddenly and dramatically while still fully green, then whole runners, then the plant. No yellowing, no spots — just collapse. Cut the stem, touch the two cut faces together and pull them slowly apart: sticky white threads stretch between them.
How to know it is this one
The string test: cut stem, press the faces together, pull apart. Sticky threads confirm it.
2.Cucumber Beetles
Act nowPest
Small yellow-green beetles a quarter of an inch long with either three black stripes down the back or twelve black spots. They chew holes in leaves and flowers and drop off the plant when disturbed.
How to know it is this one
Yellow-green beetles with black stripes or spots, about a quarter inch.
3.Fusarium Wilt
Act nowFungal disease
Yellowing and wilting that often affects one side of the plant, or one branch, while the rest looks fine. Slice the main stem lengthwise near the base and the tissue just under the skin is stained chocolate brown instead of pale green.
How to know it is this one
Cut the stem lengthwise: brown staining in the ring just under the skin confirms it.
4.Squash Vine Borer
Act nowPest
A squash plant that was fine yesterday collapses completely, usually in the heat of the day, and does not recover overnight. At the base of the stem there is a small hole surrounded by sawdust-like frass that looks like wet orange breadcrumbs.
How to know it is this one
Sudden, total collapse rather than gradual decline.
5.Squash Bugs
TreatablePest
Flat grey-brown shield-shaped bugs about half an inch long, clustered at the base of the plant and under leaves, with grey nymphs alongside them. Neat rows of bronze eggs are laid in the V between leaf veins. Leaves develop yellow speckling then brown and die.
How to know it is this one
Neat, regularly spaced bronze eggs in the angle between leaf veins. Nothing else lays like this.
6.Underwatering
TreatableGrowing conditions
Drooping leaves that feel dry and papery, crisp brown edges and tips, and soil that has shrunk away from the sides of the pot. The whole plant looks deflated, and lower leaves go crisp and yellow before dropping.
How to know it is this one
Leaves dry and crisp rather than soft and limp.
Still not sure?
The diagnostic key adds two more questions — which part is affected and where the trouble started — and those usually settle it.
Run the diagnostic key