May 29, 2014

Gardening: Knock-out roses are resistant to disease but not immune

Q. My 3-year-old knock-out rose bush is dying. It gets a new shoot that looks real healthy and gets a bud. Then it starts to wilt and it dries up and dies. Is something going on with it?

-- C. D. of Belleville

A. Knock-out roses are one of the best varieties to grow, especially for disease resistance. But they are not completely free of fungal diseases. The leaves are susceptible to black spot, powdery mildew and rust, which affect the leaves and can be prevented by fungicides.

The disease you are describing is Stem Canker. This disease starts somewhere on the stem and kills the stem and everything above the injury. Inspect each stem for a reddish-brown injury where this disease starts. On your dead stems, start going down the stem to locate the injury. Then you can brush citrus oil over the spot and trim everything off above this spot to keep it from spreading. As you well know now, the stem will die anyway.

It is spread by water droplets splashing the spores to different stems. You can control some of this spore problem by watering close to the soil and not splashing the stems or leaves.

Remember the plant has only so much reserve energy, and this constant dieback can kill the plant.

Q. When should I prune hydrangeas and what is the proper procedure?

-- G. P. of Belleville

A. Improper pruning is the No. 1 reason hydrangeas do not bloom from year to year. The best time to prune is right after the plant has finished blooming. Hydrangeas overwinter with floral buds already on the stem. Late-fall to early-spring pruning removes the branches bearing the floral buds.

You still have time to do this right now. You can prune the stems back to just above where leaves are found. You can shape up the plant with this pruning as well.

Q. We would like to know how to sprout peach and cherry seeds. We have tried everything and had no success.

-- L. K. of Collinsville

A. First, I want to warn you that peach and cherry trees do not breed true from seed. If you want to raise fruit, you should buy a grafted tree from a nursery.

But if you are interested in just germinating these seeds, there a few things you can do to make germination more successful. First soak the seeds in water for 24 hours. Then place these seeds in a plastic bag filled with peat moss or vermiculite. Place this bag in a refrigerator about 40 degrees. Keep them in this condition for a minimum of three months. Four months will be better. Then plant them outside in the spring and wait for germination.

If half of the seeds germinate, that is greas success, as some have thicker sead coats than others.

When the small trees are about 10 inches tall, you can plant them in another area. Leave the original seed bed alone as more seeds will germinate over three years.

Charles Giedeman is a local contributing writer. Send your gardening questions to Lifestyle Editor Pat Kuhl, Belleville News-Democrat, P.O. Box 427, 120 S. Illinois St., Belleville, IL 62222-0427. Or email to

Do it now

FUNGICIDE: With all the reccent rain, be ready for fungus attacks, A preventive fungicide spray will help control the start and spread of fungi.

FRUIT TREES: Thin any excess fruit. Most fruit should be spaced 6 to 8 inches apart on a stem for larger fruit production.

WEEDS: Pull all the germinating weeds in the vegetale garden while the plants are still small. It makes the job easier. Then apply a mulch to prevent future germination.

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