There’s no question that I’m a big fan of beets, so I wasn’t happy to see spots on many of the leaves a week ago. After a little investigation, I determined it’s most likely Cercospora leaf spot. For the other beet lovers out there, I wanted to share a few tips on handling this fungal infection that makes the plants look bad and decreases production.

Planting Beets During the Fall Growing Season

Cercospora leaf spot affects beets, Swiss chard and sometimes spinach. Normally, it’s more of a late season disease. But rainy and cool-ish weather perpetuate the disease. So does overhead watering because it disperses the spores. After a rainy, cool and very windy spring and early summer, it doesn’t surprise me that this infection raised its head at this time.

How to tell if it’s Cercospora leaf spot

The main giveaway of this infection are circular grayish spots with red margins. When allowed to perpetuate, it’ll ruin the leaves on the plants. Plus, it’s not appealing to eat greens with a fungal infection. Because I love the beet greens as much as the beets, it’s time to take action.

Handling the leaf spot issue

The first step is removing the affected leaves. These went into the trash. I don’t recall any of the plants suffering from it last year. But because it can last in the soil a couple of seasons it’s important to clear out debris from affected plants.

Next, spray the plants with a fungicide. I have a copper fungicide on hand, but a potassium bicarbonate based fungicide is also useful. There are also a number of synthetic options, including combinations of fungicides because, in some areas of the country, the fungus has developed a resistance. If you reside in the Northeastern part of the country, you might want to talk to your Extension agent for us more specific recommendations.

The Swiss chard is in proximity to the beets, so I am spraying them as well as a preventative. Of course, follow the labels do you understand the time period required between the fungicide application and harvesting. 

Keeping ahead of leaf spot for next season

As I mentioned, the spores from this fungal disease stay in the soil for a long period of time. Even though I should be able to knock out the issue this season, I don’t want to fuss with it next year. The first thing I’ll do is change the location of those crops in the Chenopodium group, which include beets, chard, spinach, the strawberry spinach I love, plus the “weedy” lambsquarters. I might go as far as to grow them exclusively in raised beds or containers next year. I’ve had spinach and beets in this area for several seasons and wonder if that’s where the infection originated because even though the spores can exist in the soil, they can also be present on the seeds. Next year I’ll also look for Cercospora leaf spot resistant varieties to be extra safe.

Another consideration is to utilize mulch and drip irrigation. Because the spores are spread with rain or overhead sprinkling, using a drip hose reduces the incidence of this. And using mulch cut down on how the rain drops bounce and potentially spread the disease.

It’s always a bummer to have to deal with a fungal issue in favorite crops, but thankfully the affected plants were caught soon enough that I can stop it. I won’t be able to eat quite as many beet greens, but thankfully I’m confident I’ll enjoy the delicious beet roots by the end of the summer.