Garden squash

An arrangement of colorful squash, gourds and pumpkins.

Are you entering anything in the Ravalli County Fair? The deadline to submit entry forms is Friday. This Friday.

Q: About this time last year my squash got the disease that turns the leaves gray and then kills them. Is there a way to keep that from happening again this year?

A: Your squash got powdery mildew, the fungal disease that descends upon plants in August. Powdery mildew is not truly a single disease; there are several types that attack different plants. Your squash fell victim to a common kind, which infects squash, pumpkins, melons, and cucumbers. If your lilac leaves are getting gray spots, that also is powdery mildew, but a different variety. The one on beebalm leaves is still different. The three kinds specialize on particular plants. The powdery mildew on the beebalm will not jump to the squash.

Powdery mildew spreads quickly in typical August weather -- warm, sunny days and cool nights. Because the spores which carry the disease live here, there is no way to make powdery mildew go away. There are ways to steer the fungal spores away from your squash plants, though, and send them hunting for other plants to attack.

Powdery mildew spores drift through the air and drop onto leaf surfaces, most often in early afternoon. Once there, the spores literally drill into the leaves. But the leaf has to be dry for spores to drill holes. Sometimes spraying the squash leaves with water in early afternoon will keep the fungus out of the leaves for that day.

Powdery mildew also spreads most quickly on plants suffering from any kind of stress. In this area plants often are stressed from trying to have their water supply keep up with their demand. Water your squash when the soil surface dries out. Keep the surface moist as long as possible by covering it with mulch.

Squash plants should be growing like gangbusters at this time of year. If they are not, they may be stressed by a shortage of nutrients. Try giving them some fertilizer — just a little and just once.

Squash are big plants with big leaves, and they also need good air circulation to fight off powdery mildew. Give the plants enough space when you first set them out. If a squash grows in an unexpected direction, it may be advisable to prune a few leaves here and there. Although it usually is a bad idea to cut leaves off any vegetable, in this case removing a few leaves may be the lesser of two evils. Cut only leaves which block the air flow to other parts of the plant.

When powdery mildew makes an appearance, it is not too late to try other control methods. Of the various sprays which are recommended, I have seen good results only with neem. Even neem, which sometimes seems too good to be true, will not destroy all the powdery mildew, but a weekly spray will slow the disease. Baking soda has been ineffective for me.

Once you notice powdery mildew on a squash leaf, cut off the leaf and destroy it. To leave it in the garden would turn it into a breeding ground for more disease spores. When the growing season is over, the usual recommendation is to put the squash remains in a compost pile rather than leaving them in the garden.

Next year when you can make a fresh start with squash, buy only varieties which are described as mildew resistant. That term does not mean that they are mildew proof, but at least their leaves will not seem to be issuing invitations to every spore that drifts by. Using a combination of control methods should keep your squash healthy enough to make a crop.

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Q: I like to grow poppies, but most of mine get ugly brown stems. What can I do about it?

A: You will have to resort to subterfuge. While California poppies continue to look fairly nice after their flowers are gone, other poppies do not. Both the large and the small annual poppies, as well as the perennial Oriental ones, have ugly legs. If you do not want to increase your supply of Oriental poppies by having them ripen seeds, you can cut the flower stalks to the ground as soon as the petals fall. The leaves will age and die, but their transformation is brief. There will be a new flush of leaves (although not a second flowering) in August.

poppy flower

As beautiful as the blossoms can be, poppies can have ugly legs.

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Annual poppies present a slightly different problem. Gardeners keep a supply of annual poppies by letting some seeds ripen. By the time that seeds are mature, ready to spill onto the ground to start next year's poppies, the plants are somewhere in the range between dry yellow and dead brown. This is true of all types of annual poppies — the big opium and peony poppies, the medium sized Shirley poppies, and the smaller Iceland poppies. Incidentally, those plants actually originated in Asia, not Iceland.

Old flower heads can be clipped off for a while, but some need to mature for replacements. The solution for all these poppies is to plant something in front of them, some low-growing annual or perennial to hide the bare and discolored stems. As usual, it is not necessary to block the poppies from view completely. It is necessary only to provide something else to look at. Eye and brain will focus on the other flower, and the homely poppy stems will become invisible.

Q: How can I keep bush and tree suckers out of my lawn?

A: You can't. Some bushes (like lilacs) will always sucker; some trees (like aspens) will do the same. If you have only a few suckers, you can clip them off at ground level. If there are a good many, you can mow them with the grass. That is what I do with a band of suckers next to a lilac hedge. With regular mowing, they never have a chance to be anything except a two-inch ground cover.

Whichever method you decide to use, stay with it. As long as you are persistent, the suckers' maximum height will be equal to the lawn grass. Do not decide to get rid of suckers once and for all by digging them out. It would have the opposite effect. Injuring a root results in its growing ever more suckers.


One of the fashionable terms these days is "carbon sequestration." It refers to storing carbon in the earth rather than releasing it into the atmosphere, to contribute to atmospheric carbon dioxide and global warming. Gardeners should be pleased to know that they are leading the efforts to store carbon.

An experiment last year at the University of Wisconsin found that green plants in the city of Madison were storing more carbon than were nearby forests and fields. To fight the good fight, gardeners need do only what they are already doing. Do not till more than necessary, since digging and tilling release greenhouse gases. The greater the biomass of plants you grow, the more carbon you store. Every green plant, even lawn grass, stores carbon.