When this common plant disease shows up, you’re gonna wanna act fast.
Use these tips to keep powdery mildew from ruining your squash harvest.
It’s one of the most common diseases in thevegetable garden.
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The fungi that cause the disease are somewhat specific to the plants they target.
Symptoms range from mild, which may only slightly reduce yields, to severe, killing the entire plant.
Here’s how to prevent powdery mildew on squash plants, plus tips for minimizing damage to infected plants.
Credit: Dean Schoeppner
What is powdery mildew?
Lots of plants, both edible and ornamental, can get powdery mildew.
The disease can be introduced to the garden on plants purchased from the nursery or spores in the soil.
It’s spread by wind, insects, and ongarden toolsand hands that touch infected plants.
Powdery Mildew Symptoms
Powdery mildew on squash (and other plants) is pretty simple to identify.
These quickly spread out and can cover most of the leaves and stems.
Leaves turn yellow, then brown and brittle, and finally curl up and fall off.
Diseased plants usually produce fewer and smaller fruit.
Loss of leaves can expose fruit totoo much sun, and they may become scorched.
If the powdery mildew continues to spread, the entire plant may turn brown and die.
Somevarieties of squashhave leaves that naturally feature white markings.
If the markings don’t budge, you’re ok. First, remove infected leaves as soon as you detect the white powdery spots.
If any plants show severe symptoms, remove them altogether.
And avoid handling healthy plants after touching diseased plants.
This is a sure way to spread the disease.
The same applies to tools used on diseased plants.
verify first to wash your hands anddisinfect your toolswith a 10% bleach solution.
Several organic sprays can help minimize the disease.
They’re most useful early in the infection; they won’t cure powdery mildew once it’s severe.
One of themost effective sprays is neem oil, an extract from the tropical neem tree.
It’s a good control for mild to moderate powdery mildew infections.
Spray both upper and lower surfaces of leaves.
Sulfur sprays and stylet oil fungicides will also reduce the spread of powdery mildew.
Only spray when temperatures are below 90F to prevent burn and don’t spray when bees are active.
