People who grow zucchini will undoubtedly have to contend with zucchini mosaic virus (ZMV) at some point. This insect-borne potyvirus affects all members of the squash and melon (Cucurbitaceae) family and can annihilate an entire crop in a terribly short amount of time.
Here’s how to identify zucchini mosaic virus and what to do if it appears.
What Causes Zucchini Mosaic Virus?
Unlike fungal diseases such as powdery mildew, which are caused by environmental factors such as humidity and soil-borne pathogens, zucchini mosaic virus (also known as zucchini yellow mosaic virus, or ZYMV) only has one known origin: insects.
It can be transmitted by cucumber beetles, but it’s most often spread by aphids.
You’ve probably seen these little jerks teeming over plants in the past and figured they weren’t doing much damage. Oh, you were wrong. Not only do they harm plants by sucking the sap (i.e., the very life force) out of them like four-millimeter-long vampire demons, they’re vectors for diseases such as ZMV.
If they feed from infected plants and then fly over to your garden, they’ll infect your healthy plants.
As for cucumber beetles, they’re yellow and usually either spotted or striped, and can be found chewing on zucchini, cucumbers, pumpkins, and melons alike.
Symptoms
Although the most common symptom of zucchini mosaic virus is the mottled green and yellow mosaic-like patterns on their leaves, there are additional symptoms to watch out for.
Even if that mottling doesn’t show up immediately, you may notice that some of your plant’s leaves look puckered—rather like someone has pulled a thread around them and drawn them into a cup-like shape.
Additionally, any fruits that may have been developing may be stunted or deformed or even have a rough, sandpaper-like texture to their skins.
Inspect your plant thoroughly for aphids if you notice any of these symptoms.
Treatment
There is no cure for zucchini mosaic virus. As such, if you notice any plants that are affected by it, pull them up and burn them immediately.
Then, monitor the other plants in the vicinity closely to see if they’ve been infected as well. This virus spreads like wildfire, and the only way to eliminate it is to destroy any and all infected plants.
After that, you’ll either need to let the ground go fallow, or don’t plant any squash, zucchini, melons, cucumbers, or pumpkins in that area for several years. Aim for hardy root vegetables, legumes like beans and peas, or herbs instead.
How to Prevent Zucchini Mosaic Virus
The adage that “an ounce of prevention is worth a pound of cure” holds true, to some extent here.
Although we can’t prevent aphid infestation unless we grow our zukes in hermetically sealed greenhouses, we can do our best to provide our plants with the conditions that will benefit them the most.
Choose Virus-Resistant Cultivars
When buying your seeds or plants, aim for those that have been bred to be resistant to zucchini mosaic virus. ‘Dunya,’ ‘Desert,’ ‘Golden Glory,’ and ‘Spineless Perfection’ are some of the most popular varieties that are known to be resistant to this disease.
Take Care of Your Land and Tools
Turn over your soil thoroughly before planting to expose cucumber beetle grubs to predators that feed on them, including soldier beetles, ground beetles, and braconid wasps.
Many birds, such as sparrows, grosbeaks, bluebirds, and orioles, will eat the beetle larvae as well as the adult beetles, so having bird feeders around the area can draw these predators over.
If you’ve dealt with zucchini mosaic virus in the past, avoid planting any Cucurbitaceae plants in that area for about five years.
Keep the entire area free of weeds and plant detritus, and ensure that you sterilize your tools after every use. Aim for a 10-15% bleach solution to kill any viral pathogens and minimize spread.
Companion Planting
Companion plants can be beneficial as they have the potential to deter aphids, thus keeping them off and away from your zucchini.
It’s difficult to get zucchini mosaic virus from aphids if they’re hightailing it in the opposite direction. The following plants are known to deter aphids, and may be immensely beneficial when interplanted amongst your zucchini vines or bushes.
- Garlic
- Garlic chives
- Onions
- Leeks
- Dill
- Parsley
- Rosemary
- Lavender
- Catnip
- Savory
- Nasturtium
- Marigold
- Geranium
- Yarrow
Note that some of these plants also pull double duty. In addition to fending off aphids, flowers such as marigolds, nasturtiums, and dill are known to attract ladybugs. Additionally, yarrow draws parasitic braconid wasps, which prey on aphids rather heartily.
Insect Pest Management
Ladybugs are known aphid assailants, so aim to either release as many into your garden as possible or attract them by any means necessary. The aforementioned plants are ideal for attracting them, but you can also lure them in with angelica, coreopsis, fennel, and angelica.
Just don’t plant these too close to your zucchini, as both fennel and angelica can stunt their growth.
Adult lady beetles can eat around 50 aphids per day, and their growing larvae are capable of consuming their own body weight in aphids on a daily basis. Seriously, if you have an aphid problem, ladybugs are your best friends.
Additionally, beneficial nematode worms can do wonders for annihilating cucumber beetle larvae in the soil. They should destroy the grubs before they have a chance to wreak havoc on your plants and spread ZMV around.
Manual and Chemical Controls
You can try to eliminate aphids when and if they appear before they can spread zucchini mosaic virus to your plants. One of the quickest elimination methods is to blast them right off your plants with direct water streams from your garden hose.
Alternatively, if you need to let off some steam, fill a super-soaker water gun and blast them off to your heart’s content. Alternatively, you can crush them with your fingertips or douse them in diatomaceous earth.
Another option is to hose them down with neem oil spray. Combine four cups of water (around a quart) with half a teaspoon of dish soap and two teaspoons of neem oil, which you can get at just about any Indian grocery store, or online.
Combine well, transfer into a spray bottle, and shake thoroughly. Spray your plants with this liquid to deter aphids and eliminate those that are already there, as they can’t stand this stuff.
As far as cucumber beetles go, since they’re most often attracted to yellow and orange hues, you can wrap sticky tape in these colors around some of your zucchini branches to trap them.
Just don’t set sticky traps out in the yard, as these can also trap beneficial insects, butterflies, small mammals, amphibians, and even small birds, leading to a slow, excruciating death. You can also pick off the beetles when you see them and drown them in soapy water.
