Gardening with Xpress: Wet spring sprouts mold in all the wrong places

UN-FUN FUNGUS: This cucumber is losing the fight against a fungal disease, a common wet-weather problem. Photo courtesy of the University of Maryland Extension

What a wet one it’s been! As you scurry between raindrops to tend your garden, don’t forget to send questions to me at

How to combat rot and mold

It’s been so wet; I’m worried about rot and mold. What can I do to prevent and treat them?

Living as we do in a temperate rainforest, it means that we deal with lots of fungal pathogens (rots, molds, rusts, wilts) in the garden and in our lives in general. When I began gardening here, I noticed this, got discouraged and then got really into mushroom cultivation. If you can’t beat ’em, join ’em! While I still enjoy cultivating mushrooms, I’ve learned to adapt to our warm, wet conditions and the welcome that offers to many kinds of mushrooms and molds, including pathogenic fungi in the garden.

The first thing to consider with any pest or disease in the garden is the quality of your soil and growing conditions. Plants that have what they need (soil nutrients; enough water, but not too much; enough sunshine; airflow; proper temperature) are much less susceptible to infection, even when pathogens are present. They’re a lot like us in this way. If a dozen people go to a party where one person has a cold, not all 12 healthy people will come down with the cold. Those with weakened immune systems are more likely to contract the cold, just as plants with weakened defense systems are more likely to contract diseases. 

In terms of fungal pathogens, airflow and sunlight are especially important factors. When you plant too tightly, the warm, wet air between plants doesn’t move much, creating the perfect conditions for fungi to flourish. Similarly, if you already have a partially shaded garden and then we get a week of cloudy, rainy weather, the disinfecting power of the sun’s ultraviolet rays don’t have a chance to ward off issues. So, plant with some space between plants, utilize trellising so that plants are up off the ground, prune when appropriate (especially tomatoes) and grow your garden in the sunniest spot possible.

The second thing to do is choose varieties that are suited to your growing conditions. Here, that means varieties of crops that are resistant to fungal pathogens like downy mildew, late blight, powdery mildew, botrytis, fusarium wilt and others. A great way to figure out what varieties grow well here is to talk to commercial growers at tailgate markets and to other gardeners in your neighborhood. Some disease-resistant varieties that I especially like are the DMR basil series from Johnny’s Selected Seeds and a tomato variety called West Virginia 63, which is available from various sources and is significantly resistant to late blight.

Third, practicing good hygiene in the garden and with your hands and tools can prevent and/or slow the spread of all pathogens, fungal and otherwise. This means keeping things tidy, removing diseased leaves or whole plants when you notice them (depending on the issue), clearing around the edge of the garden, and washing your hands and your tools after touching each kind of crop if it’s susceptible to fungal diseases or is clearly infected. Many fungal pathogens overwinter in debris like mulch. In general, I’m a big proponent of mulching with organic material like straw or dry leaves, but if you’re struggling with diseases, it can help a lot to clear things away for a while to allow sunlight and airflow in. 

Finally, there are some organic products that can help with both prevention and treatment of fungal pathogens. Regalia ASO is a biofungicide that’s made from an extract of giant knotweed (Reynoutria sachalinensis). It strengthens plants’ natural defense systems and helps prevent a whole host of fungal issues, such as powdery mildew, fusarium, botrytis, downy mildew, early blight, brown rot, stem rot, fireblight and more. Serenade ASO is another biofungicide — this one based on a soil bacterium — that also increases plants’ defense systems and can kill some fungal and bacterial pathogens. Copper sulfate-based products can be effective at controlling blights. 

Before treating any disease, it’s important to properly diagnose it. If your plants are simply suffering from a nutrient deficiency, over- or under-watering, or a lack of sunlight, spraying them obviously won’t help. I find the Arbico Organics website pretty helpful for diagnosing based on symptoms, and it also happens to sell lots of organic products. To really be 100% sure of what you’re dealing with, you can have a tissue sample analyzed by the N.C. State Plant Disease and Insect Clinic, or bring it to our local Cooperative Extension office to get help figuring out what’s going on.  

Some greens can’t handle wild weather ride

My mesclun mix never got very big and now is making flowers. What did I do wrong?

Growing mesclun in the mountains is just tricky. You probably didn’t do anything wrong, other than try to grow something that’s not exactly suited for our springtime conditions.

Mesclun is a mix of tender greens used for salad. The word, and idea, originated in Provence, France, where the mix included lettuces, arugula, chervil and endive. Now various cutting-salad mixes are called “mesclun,” and they can include other greens such as spinach, chard, radicchio, mustard greens, and sorrel. Even though the exact crops and varieties in a mesclun can vary, they are always a blend of tender greens that like cool temperatures. 

Mesclun grows best in places with mild climates and minimal temperature fluctuation during the growing season. Our mountains don’t tend to offer these conditions, especially in the springtime. Instead of steadily cool (but not cold) days and nights, our springs usually fluctuate wildly from up into the high 70s to down below freezing and back again. Some varieties of tender greens can handle this, like lettuce, chard, and sorrel, but not mustards and arugulas. Both of these plants are in the Brassicaceae family (also known as “cole crops” or “cruciferous vegetables,” accompanied by kale, broccoli, cabbage, etc.), and are especially sensitive to highs and lows, which stresses out their systems. As a result, they do what any wise living being might do in an emergency: try to make seeds before they die in the chaos. 

Sometimes, if the spring is gentler, we can get decent crops of mesclun here. Other times, and especially if the plants also contend with water, nutrient or sunlight stress (getting too much or too little of any of these other essential things), they just can’t handle the wild ride. Fall is a much better time to grow mesclun here. If you want to try again, sow seeds in late summer (August or September) so that most of their growing life can happen after it’s cooled off. 

Instead of doing a mesclun mix, I like to grow different greens separately, then mix them together in my salad bowl. Lettuces tend to handle our weather better, especially those that are adapted to deal with some heat. Arugula is hit or miss, but very tasty, and you can eat the flowers if it does bolt. Austrian winter peas are one of my favorite winter cover crops, and they provide tender pea shoots in the spring. Parsley, dill and cilantro are all delicious in salads. Even wild greens like oxeye daisies, hemlock tips, chickweed, dandelions and violets can add flavor, nutrients and interest to a salad mix. It makes sense that Appalachian mesclun would be a bit different than mesclun from Provence!


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