Take These Steps to Keep Diseases From Ruining Your Garden

Viruses and funguses are among the worst gardening concerns, and we're often to blame. I spoke with Meg Cowden, fearless leader of The Modern Garden Guild and author of Plant, Grow, Harvest, Repeat about how she manages disease in her garden.

Recognize common virus and fungus problems

The most common problem that people seem to experience is powdery mildew, which appears as a white bloom on the leaves of your plants, usually squash and cucurbits.

Then there's anthracnose, which is a group of fungi, and presents as a bullseye pattern on leaves or fruits like tomatoes and peppers. It starts as a sunken spot and slowly turns into ascomycete as it develops spores.

There are also various blights that might affect your potatoes, tomatoes, annuals, or perennials. There are regional blights, too, like Apple Cider Rust in the Midwest and Peach Leaf Curl in the Pacific Northwest.

"There are plenty of diseases," Cowden told Lifehacker. "But the good news is there is a lot we as gardeners can do to be proactive and try to set our gardens up to be healthy and prepared for the diseases."

Proactively prevent the spread of disease in your garden

"It's inevitable that we're going to come across disease in our gardens, " cautions Cowden. "Whenever you can, water right at ground level; or better yet, use soaker hoses or install drip irrigation that will keep the water right at the soil level instead of allowing the soil to splash." As you water with a hose or sprinkler overhead, the soil tends to splash up--including pathogens--onto your plants. In addition to avoiding overhead watering, she advises trying mulch to help curb any splashing.

We should also rotate our plants. There are often spores in our soil that we make worse when we don't move our plants around the garden. "I always move my tomatoes to different beds than the year before, because they're always diseases the year before and I'm just trying to make it harder for those pathogens to jump to my plants year over year."

If you can, you might also want to avoid working in the garden early in the day, when plants are still covered with dew and most susceptible to disease spread. Allow the dew to burn off in the sun before doing any harvesting or pruning.

Cleanliness around your garden is also important. Cowden cleans trellises and other garden structures each year in the fall (though you can do this in the summer, too), using a 3% hydrogen peroxide solution in a spray bottle. She sprays the entire trellis and lets it dry before storing it for winter. "Even here in Minnesota's -20-degree winters, spores can overwinter," she says.

Overcrowding is another common mistake. Whenever possible, give each plant enough of their own space, with room for air to circulate around them. Spacing them out will eliminate another easy vector of disease transmission around your garden.

Lastly, Cowden emphasized how important it is to start with healthy plants. "Just like us, plants that have a healthier immune system are going to be able to fight off pathogens better than plants under duress." While the discount shelf of your local nursery may appeal to you, make sure to grab healthy vegetable plants. "With your summer vegetables, you only get one shot for this year," Cowden says.

Don't accidentally spread diseases yourself

Pruning is the first step in dealing with infection, but recognize that as you're pruning, you and your tools become the disease vectors touching your plants. Tool and hand hygiene is important, so be vigilant about cleaning your tools and hands. And when you're disposing of leaves or plants that have been infected, put them in the trash instead of your compost.

Accept when your plants are too far gone

Know when to call it quits, as each infected plant is a risk to the plants around it. "There are times I let it go a little too far," Cowden confesses. "Even if I've got very little foliage left on a tomato from pruning, but lots of fruit, I might let it ride out." But she takes a different tune on cucumbers and melons--anything in the cucurbit family. As she points out, if warm-season crops are looking terrible in August, you're losing valuable growing and harvest time still left in the season."I can still harness 6-8 weeks of growing in that space and get a nice fall crop of Chinese cabbage, beets, or lettuce--anything in that fifty day range. It's not worth wasting the space. Being present in your garden every day will help you catch these irregularities in your foliage and decide how to respond."