Sunscald
Risk near you, next 48h
See whether your local forecast favours this disease right now.
When it strikes
Fix the cause, not the leaf
No spray will help here. The trigger is soil, water supply, nutrition or temperature, so change the growing condition and judge the result on new growth, not on damaged leaves.
Not contagious
Nothing spreads from plant to plant here. Neighbouring plants showing the same signs are reacting to the same soil, water or weather, so fix the cause rather than isolating plants.
Safe to compost
No pathogen carries over on this material, so it can go on an ordinary heap with the rest of the garden waste.
When and where to look
Scout the planting while temperatures hold between 32°C and 45°C, in dry air below 50%. Risk builds after roughly 6 unbroken hours of those conditions, so the morning after such a night is the moment to look.
The signs that lead here
About
Sunscald is a physiological injury to fruit and bark from intense sun and heat, common on tomatoes, peppers and apples when foliage is thin from pruning, disease or defoliation.
Symptoms
Pale, papery, blistered or sunken bleached patches on the sun-exposed side of fruit that may later rot; on tree trunks, cracked, sunken dead bark on the south-west side.
Organic Treatment
Maintain healthy leaf cover for shade, use shade cloth in heatwaves, and avoid heavy pruning that exposes fruit. Paint young tree trunks white to reflect sun.
Chemical Treatment
Not applicable — sunscald is environmental and managed culturally, not chemically.
Prevention
Avoid over-pruning, control leaf diseases that cause defoliation, provide afternoon shade in hot climates, and whitewash exposed trunks.
Related problems
Sunscald risk by location
Each location has a month-by-month profile computed from the weather archive: how many hours a year actually meet this disease’s thresholds.