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Last Updated on August 18 , 2023

If you ’ve also notice white-hot slur on the folio of your zucchini , squash , or melon plant , do n’t fret . Read along to learn about ashen markings on squash foliage ( and other members of the cucurbit plant home ) admit what causes white-hot spot on courgette leaves , how to tell the difference of opinion between natural folio patterns vs disease , and how to treat powdery mould .

A zucchini plant with natural variegation with white spots on its leaves is next to a squash plant with powdery mildew on its leaves.

What causes white spots on zucchini and melon leaves?

White spots on squash and melon vine foliage are usually because of one of two affair : disease or natural variegation . One can be a job , while the other is not !

Fungal diseases like powdery mildew causes white-hot spot on courgette leaf and other plants . Powdery mildew is very uncouth and may call for treatment . On the other deal , some ( but not all ) cucurbit varieties including courgette , squash , pumpkin , cucumbers and melons have natural silvery - white spots , markings , or normal on their leaves that are totallyharmless . It ’s just part of the leafage !

For example , our favored mildew - resistive courgette variety“Dunja”has hard variegated leaves , shown below . I reckon it ’s beautiful ! Similarly,“Moon and Stars ” watermelonhas innate yellow pip all over the leave-taking AND melon vine rind .

DeannaCat’s outstretched palm is underneath leaves of two different squash seedlings. One of them contains a heavy amount of white variegation while the other is mostly green. Both of them are fully healthy squash seedlings.

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Three raised garden beds are shown overflowing with various vegetable plants and flowers. The main plant that is center stage is a zucchini variety squash plant, it is quite large and has white or gray molting on its leaves. Various squash fruit are growing, poking their flowered ends towards the sky. The other beds contain onions, basil, kale, and beans, along with marigolds, zinnia, calendula and borage.

How to tell the difference between natural variegation and mildew

clean spots on courgette leaves make by naturalvariegationare commonly fairlyuniform , displayed in a mirrored convention on all leaves and concentrate around leaf veins . The grading areflat(not call down ) and only seeable on the top side of the folio .   Natural variegation pattern typically appear when the squash or melon flora are stillyoungseedlings .

In demarcation , powdery mildew(PM ) spots are more atypical andscatteredthan lifelike variegation – some big spots , some little spots , and some leave with none at all . Mildew white spots are usually round , fuzzy , stale - look , sometimes slightly enkindle , and can be notice on both the top and bottom of zucchini leaves and stem .

Powdery mold generallyshows up laterthan variegation , with the oldest leaves becoming most heavily infected .   A severe mildew pillowcase makes the works look like it ’s been sprinkle in powdered sugar or flour ! The infected   leaves may finally turn icteric and dry out out too . Mildew white spots can also be wiped off ( or at least appear to temporarily vanish ) with a soused textile or theme towel , whereas the natural folio pattern would ride out as - is .

An image of two smaller watermelons growing in a patch, the melon as well as the surround leaves are all covered in yellow spots and splotches which is normal for this particular variety.

Powdery mildew vs downy mildew

Powdery mildew causes muzzy , slightly raised , irregular white spotlight on industrial plant leave . The unsound the infection get , the more buddy-buddy and “ powdery ” it becomes . On the other hand , downy mold creates smallyellow spotson leaves that finally turn chocolate-brown , thin , and crispy .   Learn more about controlling pubescent mildew in the gardenhere .

How to get rid of white spots (mildew) on zucchini plants

Once you ’ve confirmed the white spots on your zucchini leaf are indeed a fungal disease ( and not just a natural leafage pattern ) , you’re able to go forward to handle the plant life as necessary . The course of action to handle powdery mildewdepends on the extent of the infection . Thankfully , powdery mildew is n’t black to plants except in extreme cases . Yet mildew does hinder overall plant health and can easily spread to other plant in your garden , so do n’t countenance it go unchecked .

Powdery mold can bepreventedby if you opt mould - resistant varieties , avoid overhead watering ( usedrip irrigationinstead ) , sanitise garden prick regularly , and follow recommended plant spacing to reduce crowd and growth circulation .

Treatmild cases of mildew by prune away infected leaves , put on adilute neem crude sprayafter dusk , DIY baking soda spray , or our favorite method : with homemade potassium hydrogen carbonate spray , explicate below . I recommend off and trashing ( not composting ) severely infected plant to avoid the spread of mildew spore in your garden .

A close up of irregular white spots on zucchini leaves.

See this article to con even more about organic powdery mildew direction .

Using potassium bicarbonate to treat powdery mildew

Potassium bicarbonateis a born compound like to broil soda ( Na hydrogen carbonate ) but is warm and longer - lasting against powdery mildew . It changes the pH on the plant life leaves , making conditions more alkaline and less hospitable for the fungus to thrive . It can be used as a prophylactic spray on vernal flora , or as treatment once snowy spots appear on parting . Potassium bicarbonate isnontoxicto humans , wildlife , and the environment , though you should exercise caution not to inspire the powder or get it in your eyes .

To create a potassium hydrogen carbonate spray for powdery mold , thoroughly mix1 tablespoonful ofpowderand 1 Tbsp ofliquid castile soapwith 1 gallon of waterin yourfavorite garden sprayer.(The Georgia home boy helps the potassium hydrogen carbonate spread and stick to the leaves well . ) Shake well and spray the plant life thoroughly , saturate both the spinning top and bottoms of leaf . Repeat discussion as needed , but no more than once every two weeks . As with all foliar sprays , it ’s best to apply in the evening hours once the plant are out of lineal sunlight .

And that’s the difference between mildew and variegation on plants.

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A vining melon is trained up a trellis system, the newer leaves towards the top look fairly healthy while the older leaves towards the bottom are covered in powdery mildew.

A two way image collage showing two separate cases of powdery mildew on squash leaves. The first image shows a few darker green leaves, one of them is almost fully covered in powdery mildew while the leaf next to it just has a few splotches. The second image shows a couple more squash leaves that have been infected with powdery mildew while the remaining newer leaves are disease free for the moment.

A two part image collage, the first image shows the top leaf of a PM resistant variety of squash. There are natural gray variegation on the leaves that are fairly symmetrical across the whole leaf. The second image shows DeannaCat turning the leaf over so you can see the underside which looks green and healthy where as plants inflicted with PM will usually have spots on the undersides of their leaves as well. White spots on zucchini aren’t always disease related, natural variegations are common in some varieties.

A large zucchini plant that is absolutely covered in powdery mildew, almost all of the green leaves are now covered in thick, white, powdery mildew.

A hand is using a small handheld pump sprayer to spray an artichoke plant that is infected with aphids. The artichoke is planted in a half wine barrel amongst bark mulch ground cover, various shrubs, flowering annuals, and perennials. White spots on zucchini can be prevented with routine, preventative foliar sprays.

DeannaCat signature, keep on growing