Take These Measures to Prevent Disease From Ruining Your Garden

Viruses and fungi are some of the most serious problems in the garden, and often we ourselves are to blame. I spoke with Meg Cowden, the intrepid leader of the Guild of Modern Gardeners and author of Plant, Grow, Harvest, Repeat, about how she handles disease in her garden.

Recognize Common Virus and Fungal Problems

The most common problem people face is powdery mildew, which appears as a white coating on the leaves of your plants, usually cucurbits and gourds.

In addition, there is anthracnose, which is a group of fungi and is an apple-shaped pattern on leaves or fruits such as tomatoes and peppers. It starts as a sunken patch and gradually develops into an ascomycete as the spores develop.

There are also various diseases that can affect your potatoes, tomatoes, annuals or perennials. There are also regional diseases such as apple cider rust in the Midwest and peach leaf curl in the Pacific Northwest.

“There are many diseases,” Cowden told Lifehacker. “But the good news is that there is a lot we can do as gardeners to take the initiative and try to set up our gardens to be healthy and prepared for disease.”

Proactively prevent the spread of disease in your garden

“We will inevitably encounter disease in our gardens,” cautions Cowden. “Water directly at ground level if possible; or, even better, use wetting hoses or install drip irrigation that will keep the water right at soil level rather than letting the soil splatter.” When you water with a hose or overhead sprinkler, soil, including pathogens, can get onto your plants. In addition to avoiding watering from above, she advises using mulch to keep splashing at bay.

We also need to rotate our plants. Our soil often has spores, which we exacerbate when we don’t move our plants around the garden. “I always move my tomatoes to different beds than last year because they are always diseases the year before last and I’m just trying to make it harder for these pathogens to jump on my plants year after year.”

If possible, avoid gardening early in the day when the plants are still covered in dew and are most susceptible to disease. Let the dew burn off in the sun before you start harvesting or pruning.

Cleanliness around your garden is also important. Cowden cleans trellises and other garden structures every year in the fall (although you can do this in the summer as well) using a 3% hydrogen peroxide solution in a spray bottle. She sprays the entire trellis and lets it dry before putting it away for the winter. “Even here in Minnesota’s minus-20-degree winter, spores can overwinter,” she says.

Overcrowding is another common mistake. When possible, give each plant enough space to allow air to circulate around it. Distance between them will eliminate another easy disease vector in your garden.

Finally, Cowden stressed the importance of starting with healthy plants. “Like us, plants with healthier immune systems will be better able to fight off pathogens than plants that are under pressure.” While a discounted shelf at your local nursery may appeal to you, be sure to stock healthy vegetable plants. “With your summer vegetables this year, you only get one chance,” Cowden says.

Don’t accidentally spread disease yourself

Pruning is the first step in controlling infection, but remember that while pruning, you and your tools become carriers of diseases that affect your plants. Tool and hand hygiene is very important, so be vigilant about washing tools and hands. And when you dispose of infected leaves or plants, throw them in the trash instead of compost.

Accept when your plants have gone too far

Know when to stop, as every infected plant poses a danger to the plants around it. “Sometimes I went too far,” Cowden admits. “Even if a tomato has very little foliage after pruning, but a lot of fruit, I can let it wait.” But she has a different attitude to cucumbers and melons – to the entire gourd family. As she points out, if the warm-season harvest in August looks terrible, you’re wasting valuable growing and harvesting time left in the season. “I can still use 6-8 weeks growing in this space and have a good fall. Chinese cabbage, beetroot, or lettuce crops are all within that fifty-day range. Don’t waste space. Being in your garden every day will help you pick up on those irregularities in your foliage and decide how to respond.”