Milk just may be your garden remedy

Posted9/6/2015 1:01 AM

GOT MILK? Yes, milk!

That summer fungus, otherwise known as powdery mildew, is showing its powdery white markings and the newest war on powdery mildew is MILK!


Sphaerotheca fulginea and Erysiphe cichoracearum are the fungi responsible for the white powdery markings on your cucumbers, pumpkins, melons, squash and other vegetables. In addition to trees and shrubs, your flowers are not spared as it can be found on Monarda and Zinnia.

The pathogen seems to be a problem from July to early September when the days are hot and dry and the nights are cool with a high humidity level. It can develop in just three days with these types of conditions. The fungus is typically introduced by spores spread by windblown rain from warmer climates, where it overwinters. It can also come in on the feet of insects and birds. So, even the cleanest of gardens can be affected.

Powdery mildew is host specific so just because it is on one plant does not necessarily mean it will make its way to other plants in your garden. There are, however, many different species of powdery mildew and the symptoms all look alike. When the species finds a host plant it will send its rootlike structures into the cells on a leaf surface. It starts taking nutrition from the leaf while developing a threadlike structure over the surface. This cripples the ability of the plant to conduct photosynthesis by blocking out the light and stopping the leaf's gas exchange system.

What's a gardener to do?

• Clip out leaves that show early spotting.

• Look for disease resistant varieties of plants

• Provide air circulation around plants. Don't crowd them out.

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• Slow-release fertilizer makes the plant less susceptible as new growth is more vulnerable.

• Try the 40 percent milk/60 percent water spray, which has been shown to be as effective as chemical fungicides. Scientists think the proteins in the milk interact with sunlight to create a brief antiseptic effect but it must be used preventively, applied on sunny days and repeated every 10 days or so.

The symptoms of powdery mildew usually look worse than the actual damage and it is rarely fatal.

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-- Bev Krams

Q. Can I still plant vegetables now for a fall harvest?

A. Yes, you can plant many vegetables now and get a good harvest before the end of the growing season. In fact, some cool season crops like peas, broccoli, spinach and lettuce actually prefer maturing in the cooler weather.

First, you need to consider when we are likely to experience the first frost, which will probably kill warm season crops like tomatoes, peppers and green beans. The average first frost in the Chicago area is about Oct. 15 (near the lake, this date is a little bit later).


Second, you need to look at the seed packet to see how many days to harvest. The seed packet days is based on a spring planting so you need to add 14 days to that for the shorter day length in the fall. Count backward from the first frost date to determine the last date you can sow the seeds.

Also, keep in mind which crops can tolerate some frost. Some quick maturing vegetables that can tolerate some frost include kale, cabbage, cauliflower, salad greens, leaf lettuce, peas, spinach, beets, carrots, radishes, Swiss chard, turnips, scallions, Chinese cabbage and bok choy.

If you have broccoli or Brussels sprouts already growing in your garden, keep them watered and harvested until cooler weather when they will grow more vigorously again. In fact, Brussels sprouts taste sweeter once kissed by frost.

Plant the seeds a little deeper that you would in the spring and keep them moist until they emerge. If days are still hot, you should provide some shade to new sprouts and transplants until they get acclimated to the weather. Some seeds like lettuce and spinach won't germinate well in hot weather so they would benefit from shade during germination. Or you can start them indoors where it is cooler and move them to the garden once established.

Make sure you water your crops well during hot weather to avoid wilting and setbacks. Once the weather cools, you can extend your growing season by using cold frames and row covers. Or simply cover plants with an old sheet or blanket overnight when frost is predicted. Uncover the plants in the morning when temperatures start to warm up.

With a little advance planning, you can enjoy a second season of gardening in the fall.

-- Pete Landwehr

• Provided by Master gardeners through the Master Gardener Answer Desk, Friendship Park Conservatory, Des Plaines. Call (847) 298-3502 or email

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