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A Bad Case Of Spots; How To Deal With Powdery Mildew And Other Icky Plant Diseases

Fungal disease Powdery mildew on zucchini foliage
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A recent spate of wetter weather creates the perfect breeding grounds for leaf and plant diseases in your garden and raised bed. We'll learn how to combat powdery mildew and root fungus with some simple techniques.

Recently, you may be spending a good chunk of your gardening time combating those LDD moth eggs and chasing chipmunks away from your burgeoning berries.

There's another chore to tend to, especially because of recent wet weather: foliar and root diseases on everything from squash to phlox.

Luckily, there are ways to help your veggie and flower plants!

If the foliar disease is really bad, you can cut the leaves away. This helps the disease from spreading to other parts of the or other plants in your garden.

Recent heavy rains and cooler weather have contributed to rot in the soil and can wilt vines, too, but you can take some steps to protect your crop.

In the middle of the day, take a good look at the vines on winter squash or melon and note if they're wilting. If so, that's probably due to not having enough oxygen in the soil.

The best thing to do under those circumstances is work around the soil a little bit to dry it out. Your squash and melon plants might be able to outgrow the problem.

As you're taking note of those soil issues, you may also be seeing things happening on your tomato plants and tomato plant leaves. If you're seeing yellow spots on the leaves, this could be early blight septoria leaf spot.

Tackle this plant issue by pruning all your tomato plant leaves. Taking all the leaves off the bottom stems will slow down the onset of this disease. Once you've removed those bottom leaves, lay some grass clippings, hay or mulch on top of the soil.

You can also try a recipe for a preventative spray: combine one tablespoon of baking soda, half teaspoon of dish soap or a horticultural oil in a gallon of water. This concoction only works on the healthy foliage so it doesn't spread.

Soon enough, another plant disease known as powdery mildew will begin to spread. Powdery mildew naturally exists in the environment and is weather-dependent. You might see affect the foliage on lilacs, birch trees, phlox and beebalm.

If the weather turns warmer again the the mornings are cooler and dewy, expect to see powdery mildew on your plant leaves.

Q: Charlie, I have a huge hosta surrounding a newly planted shoot of my other lilac. When planted, there appeared to be plenty of room. Now the hosta is surrounding the new lilac, which appears to be holding its own. Should I pull up the hosta and replant elsewhere or will they co-exist? - Jeanne, in Chelsea


You can, indeed, pull up and replant the hosta. You can replant almost any time or leave that task till spring. Replanting the hosta to its own location will give that lilac a bit of elbow room, allowing it to thrive better and probably grow faster.

Q: Last summer deer nearly destroyed two new fruit trees I planted. Now, they are enclosed in fencing. How long do I have to keep them fenced in? Also last summer, a bear climbed into my 35-year-old Seckel pear tree, tore off several branches and ate most of the pears. How can I protect that tree? - Virginia, in Guilford

As long as that tree is low enough for deer to browse on it and really cause damage, then you probably should keep the fencing up. As for the bear, bigger fencing might be in order! Other than fencing, you can try some repellent sprays around the tree as well.

Q: After reading your No Dig Gardening book, I thought I'd take a modified approach by mulching the tomatoes in a well-established, weed-free, wood-framed raised bed with straw. I now have a bumper crop of oats that is impossible to keep up with it. How do you suggest managing it for the rest of the growing season and how should I handle the straw when the season has ended? - Erica, in Montpelier

If the oats sprouted from the bedding you laid down on top of your no-dig gardening bed, know that oats are an annual crop and do make a great cover crop! Oats do naturally die off in the winter, so if the crop is not harming the tomato plants, go ahead and just let it die off.

You can even cut it down to the ground and just drop it there as a mulch. One of the tenants of no-dig gardening is not turning or digging into the soil, so just chop and drop that cover crop and you should be in good shape.

All Things Gardening is powered by you, the listener! Send your gardening questions and conundrums and Charlie may answer them in upcoming episodes. You can also leave a voicemail with your gardening question by calling VPR at (802) 655-9451.

Hear All Things Gardening during Weekend Edition Sunday with VPR host Mary Engisch, Sunday mornings at 9:35.

Have questions, comments or tips? Send us a message or get in touch by tweeting us @vprnet.

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Charlie Nardozzi is a nationally recognized garden writer, radio and TV show host, consultant, and speaker. Charlie is the host of All Things Gardening on Sunday mornings at 9:35 during Weekend Edition on VPR. Be part of the fun and send your gardening questions here, for Charlie to answer on the air. Plus, find lots of great gardening tips and information for all seasons here. For more gardening information, check out Charlie's website, Gardening with Charlie Nardozzi. Charlie is a guest on VPR's Vermont Edition during the growing season. He also offers garden tips on local television and is a frequent guest on national programs.
Mary Engisch is the host and reporter for Weekend Edition Saturday and Weekend Edition Sunday on VPR.