Just like the human body, plants are vulnerable to all kinds of viral invaders and they can be every bit as destructive.
If you’ve ever spotted strange yellow or green mosaic-like patterns marring your beet leaves, you might have encountered one of the most common culprits: beet mosaic virus.
Also known as BtMV, this disease isn’t just unsightly, it can be seriously damaging to your crop.
While the disease rarely kills a plant outright, it can put a major dent in your harvest by damaging the foliage and stunting root growth.
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The good news is, if you’re proactive, there are ways to prevent this virus from ever gaining a foothold in your garden.
And if you’re already dealing with an infection, there are management options to help minimize the damage.
Of course, prevention starts with a strong foundation, so if you need a refresher check out our guide to growing beets.
Ready to learn more about beet mosaic virus and how to deal with it? Here’s what we’ll cover:
What Is Beet Mosaic Virus?
Beet Mosaic Virus (BtMV) is a viral disease that infects all species in the Beta genus, including sugar beets and Swiss chard, as well as spinach (Spinacia oleracea).
It is particularly fond of members of the Amaranthaceae family but also infects species in the Solanaceae family, including tobacco (Nicotiana tabacum), and Fabaceae family, such as beans (Phaseolus vulgaris) though these are less common hosts.
The disease can look similar to other aphid-borne viruses, including beet chlorosis virus (BChV), beet western yellows virus (BWYV), and beet yellows virus (BYV).
In fact, they’re all caused by related viruses. Infection manifests as mottling and distortion of the leaves, making them unsightly, and potentially reduced plant vigor and yield.
Its impact on home gardeners is typically minimal. In commercial gardens, the disease can cause significant losses, especially in sugar beets.
Identification
The only way to positively identify this disease and to tell it apart from other viruses is by sending affected plant tissue to a laboratory for testing.
The veins of the leaves might lighten and turn pale, and older leaves may pucker and develop unusual light and dark areas.
The plants might also be stunted, with distorted growth. The yellowing occurs between the veins and you’ll also see reddish-brown spots.
The leaves might become thick and leathery before they become brittle and die.
The most distinctive symptom is the mottled yellow or mosaic-pattern that develops on young leaves, but this will typically fade as the leaves age.
The symptoms are a bit different on spinach. You’ll see small yellow spots that might eventually grow and merge to form large yellow areas.
Older leaves will be entirely yellow and will die off. These plants will be stunted with distorted growth, as well.
Biology and Life Cycle
BtMV is spread by aphids, primarily the green peach aphid (Myzus persicae) and the black bean aphid (Aphis fabae). But all aphids can carry this and many other viruses.
The aphid ingests the virus from feeding on an infected plant and transmits it to a new plant as it feeds.
The virus will survive in the aphid for several hours, during which time it can be transmitted to a variety of susceptible species in the garden.
Infection can also be spread from the sap of one plant to another, though that’s less common. You could potentially spread it when pruning leaves.
While it’s always a good practice to buy certified disease-free seed, this is one disease that isn’t transmitted via seed. The pathogen can survive in dead plant tissue.
When a plant is infected, the symptoms typically start to appear in about a week, and there can be multiple cycles each season.
Prevention Methods
So here’s the bad news. Once your plant is infected, there is nothing you can do to cure it or even slow the spread of the disease.
It is, as they say, what it is. So, prevention is your only control option.
Preventing aphid infestations is the absolute best way to avoid BtMV. The aphid needs to feed for several minutes before the virus is transmitted, but it’s best to keep them away altogether.
You can do this by spraying your plant with an insecticide such as neem oil and by encouraging beneficial predatory insects.
Lacewings and ladybugs are known for being voracious aphid eaters.
It’s important not to purchase ladybugs as the market for them is contributing to their extinction in the wild.
Lacewings can be purchased at a variety of nurseries. You can buy them as eggs or larvae for release into your garden.
Arbico Organics has lacewing larvae if you want to go that route.
Green Lacewing Larvae
The most sure-fire way to prevent aphids is exclusion using fine netting. Our guide to dealing with aphids has other control methods.
If your beets are infected, you can prune off the leaves to help prevent the spread. Feel free to eat them, it won’t hurt anything.
Cleaning up the garden at season’s end is important, so there’s no dead or dying plant matter to serve as a virus reservoir.
Infected plant matter should be disposed of in the trash, not the compost pile.
Eliminate weeds that can serve as potential hosts, such as lamb’s quarters and pigweed.
And finally, make sure you rotate your crops. Avoid planting beets or other susceptible crops in the same place year after year. Rotate with brassicas or other non-host crops.
Don’t Let BtMV Ruin Your Roots
While beet mosaic virus might not be the most devastating threat in the garden, it’s still worth taking seriously.
A few mottled leaves might not ruin your harvest, but why settle for less when prevention is relatively easy?
I’d love to hear what symptoms you are seeing in your plants. You can share with us in the comments and it will help other readers in their BtMV battle, too!
And for more information about growing beets in your garden, check out these guides next: