White spots on zucchini leaves are a common cause of the occurrence; however, they can mean some potentially serious issues. If you’re a zucchini gardener discovering those yellow spots, you may naturally feel afraid, but those spots are always treatable if you know what ails your plants.
We are here to help you understand what’s going on with your leaves and how to nurture them back to health. Now, let’s see what are the four main causes of those whitey spots and how to approach each of them.
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What Are Causes For White Spots On Zucchini Plants?
The causes for white spots on zucchini plants would be due to genetics, and powdery mildew. It may also be due to different insects attacking it, or even a case of mosaic virus. Due to these reasons, you can see dots on the leaves of your crops.
Zucchini is a staple of summer cuisine which grows as an annual for the fleshy, bulbous, and delicious fruit. Until they start to show different issues, in this case, the leaves would become weaker. It is a member of the Cucurbitae family, making it a close relative of cucumbers, squash plants, and melons.
Genetics in plants, like in humans play a major part in how we are going to appear on the outside. Much like pigmentation genes can cause humans to have freckles, or colorless skin patches, the same happens with plants and can happen to zucchinis too.
Genetic mutations can cause white, yellow, and brown patterns on your plant leaves, and these yellow colors would change and become brighter as well. What makes these unique from other causes of leaf whitening is that they will appear almost symmetrical and if you spot that leaves have white stripes that follow leaf veins this likely points to a genetic mutation of sorts.
Whether the fruits of such plants are good to be consumed or not is a matter of debate, but all in all the fruits shouldn’t be affected by such leaf genetic mutations. When it is genetic, you will see it happening constantly and throughout the whole crop even when it is growing and being productive.
– Powdery Mildew
Most often than not, your white spots and patches on zucchini leaves will be caused by powdery mildew which is also known as white mold. Powdery mildew is a fungus that spreads by air and is one of the most common fungal sights on plant leaves.
It usually happens in spring and summer when the nights are humid and the days are hot and a lot of moisture circulates through the air.
Zucchini grow up to two to four feet tall and around the same in width, while vining zucchinis grow double that size. However, with this fungus hitting the plant, what can go wrong with the leaves is a sudden whitening issue, but bear in mind, close inspection and determination of your root cause will help you cure your zucchini back to health faster.
A huge number of spores attach themselves to leaves and plant stems where they create these white webbing formations. Moist is ideal to spread these spores as water droplets will carry fungus in the air, lowering them onto leaves through a condensation process.
This is the type of fungus that is easily identifiable by touching the leaves. It will appear as a white powdery substance. When you go over these spore patches, you’ll easily smear them all over the leaf.
Which means that don’t be afraid, as mildew won’t do any harm to you, but you’re more than welcome to wash your hands afterward. Powdery mildew usually starts appearing on top of the plants at first and then going and progressing to the lower parts of the plant.
Another thing causing whitening on your leaves is insects, and more specifically, aphids would start to attack and grow upon the leaves, and you will see that they are leaving their traces all over. If you notice that your spots are moving, then you’re likely dealing with sap-sucking insects.
Aphids are small white bugs that will nest on the undersides of your zucchini leaves, but they would also grow on top too. They’re translucent, but as they grow in numbers and merge they will create white unsightly spots.
They have soft bodies, covered with hard shells, because they are insects, and at this shell stage, they are most vulnerable, precisely, due to the fact that they aren’t moving much and are attached to your leaves. Your problems will begin as soon as they start to move around and mate, so you must react as soon as you spot these pesky things.
Mealybugs and spider mites are also a type of sap-sucking insects that will coexist with your aphids and generally prefer the same conditions. However, these won’t appear white but rather brown, yellow, or black. On the other hand, do remember that they too will drain your leaves of life, so it’s important to destroy them as soon as possible.
– Mosaic Virus
This one also goes by the name of ring spot virus, precisely because of the shape it creates on leaves. This is the type of issue that is a common plant diseases, and manifests itself as leaves full of white, yellow, or even dark green spots. Of the most susceptible plants, squashes, tomatoes, and especially zucchini tend to fall victim to this disease.
Fungal diseases are often difficult to verify and diagnose, but if you’ve been dealing with aphids, chances are that this virus will follow suit — aphids are common bearers of the cucumber mosaic virus type that attacks zucchini too.
As a result of the matter, you will be able to recognize this disease by yellow, white, and dark spots. Apart from leaving your zucchini yellow mosaic virus will also cause poor and stunted growth immediately thereafter.
With the cucumber type of mosaic disease, the one attacking zucchini too, the plants exhibit a so-called shoestring syndrome — a malformation where the edges of your zucchini leaves don’t develop properly and lea veins develop narrow yellow strips.
How To Prevent White Spots on Leaves of Zucchini?
To prevent white spots on the leaves of zucchini you must source the plant from a local garden if it is a genetic issue. You should also prune the weak leaves, apply some fungicides, or even spray neem oil around the crops, and make sure you cut the infected area.
– Source the Plant From a Local Garden
If white or yellow spots follow your plant from when it was just a small seedling, then you’re probably stuck with a genetics case. Young seedlings, like babies, are very much tolerant to various diseases.
If you spot these white things early on, maybe you’ve got your plant from the wrong supply, which is why you can go to a local garden, and get the mother plant from there, without any genetic issues.
Now that you know what can cause all these spots on your zucchini, it’s time to get familiar with how to treat and prevent these causes. You’ll probably be out of harm even if you eat a fruit from a GMO source or if you’ve developed the plant from the seeds of a store-bought zucchini.
But if you’d like your zucchini to be of that pristine au naturel quality, then you might want to source the plants from a local gardening center or plantation. All in all, genetic whiteness is considered rather harmless and if no stunted growth follows the spots, your zucchini is in the green.
Powdery or downy mildew is a fungal disease often connected to poor air moisture quality. Growing your zucchinis out in the field should go without the trace of mildew forming, but if you do grow them in glass houses or elsewhere where there’s a lot of moisture, you’ll probably have your share of battles with mildew.
– Spray Some Alcohol
You can even rub these oils in with some cloth and, don’t forget to wipe the undersides of your leaves. If you’d like an even more natural solution, go with some flowering neighbors, flowers will attract beneficial insects like bees and other bugs that will eat away your aphids.
Treating powdery mildew will leave you longing for those leaves for quite some time. If the disease has begun to cut into leaves, you should cut as many infected leaves as you can. Zucchinis should recover well from leaf pruning, but try to leave some good green leaves on and treat powdery mildew with some rubbing alcohol or hand soap and water solution upon it.
– Applying Fungicide
Preventing powdery mildew is a far better option. To prevent powdery mildew from forming, you’ll have to ensure good air circulation and apply a general fungicide early in the spring which should do the trick.
You can apply this solution in spring, and they will not have a risk of any attacks happening when they are being fruitful. Even if you haven’t, you apply it when different attacks have happened, and now they will be repelled.
– Spray Some Neem Oil
Aphids are easy to deal with while they’re still immobile and latched onto the leaves. You can spray them with a mixture of water and neem oil, but any other horticultural oil will do. The reason why you can do this is so that you wouldn’t go straight for the highly toxic chemical stuff, as these things can potentially ruin the very fruit of your labor with the zucchini plant.
On the other hand, mint, sage, or basil are good natural insect-repellent options. You can also use a mixture of baking soda and water, which is also great sprayed over the leaves if no neem oil is to be found.
– Cut The Infected Area
If you do notice a case of mosaic disease, then you should destroy the infected plant as soon as possible to prevent the disease from spreading to other crops. Monitor the rest of the plants for the next short period just to make sure everything is going well.
With this virus, prevention is far better than having to deal with the actual disease. As the disease is mainly spread via insects like aphids, you can protect your zucchini plant with some foil, but then again this could prevent the sun from touching the plant properly. However, aphid and weed control is your best bet at preventing this disease.
Aside from these, zucchini plants are wonderful to look at, trailing all around the garden, but if you spot something white on their leaves, be alarmed — some things will pose an absolute threat to your plants and crops, so let’s see what we’ve gone through:
- Always approach white leaves with a studying mind. Determining what ails your plant will get you halfway to the cure.
- Powdery mildew and aphids may be fairly easy to deal with, but the mosaic disease will call for a completely different response. Control powdery mildew with proper air and moisture circulation.
- To prevent those white marks, always use disinfected gardening tools, and make sure you maintain a proper fungicide regime. And always have some neem oil on you.
We surely hope that the whiteness on your zucchini plants will become a thing of the past, and wish you a happy gardening.