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| Botrytis freckles and browns the edges of a Pink Promise rose. (Photos: Debbie Arrington) |
May usually is the rosiest month in Sacramento. Warm, dry days coupled with raging growth hormones make for bountiful blooms and healthy plants.
But not this month. Sacramento area rose lovers report problems usually not seen in mid-spring: Botrytis, powdery mildew and blind shoots. All these issues can ruin rose blooms (or eliminate them all together).
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| Powdery mildew coats foliage on a Dorothy Perkins rambling rose. |
Common in late fall, botrytis attacks buds as they open, turning them to mush. It starts out looking like freckles, then quickly turns petals brown and soft. Roses quite often refuse to fully open.
Powdery mildew is primarily a foliage fungus, covering leaves and stems with what looks like an explosion of powdered sugar. (It can coat buds, too.) Its activated by temperature; days in the 60s or 70s are its sweet spot.
The good news? When days turn 90s degrees, these fungi disappear. They can’t stand high heat. The forecast for this weekend: 92 degrees.
Infected foliage and blooms will fall off and be replaced by healthy growth. Pick up these discards and dispose of them in trash (not compost). That will help cut down on reinfection.
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| Instead of a bud, there's only a stub on this Marilyn Monroe rose. |
The solution is easy: Cut the blind shoot off. Prune the stem back to just above the first five-leaf leaflet. The bush will soon sprout a new stem, most likely with a bud at the end.
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Garden Checklist for week of Jan. 19
Dress warmly in layers – and get to work:
* Apply horticultural oil to fruit trees to control scale, mites and aphids. Oils need 24 hours of dry weather after application to be effective.
* This is also the time to spray a copper-based oil to peach and nectarine trees to fight leaf curl. The safest effective fungicides available for backyard trees are copper soap -- aka copper octanoate -- or copper ammonium, a fixed copper fungicide. Apply either of these copper products with 1% horticultural oil to increase effectiveness.
* Prune, prune, prune. Now is the time to cut back most deciduous trees and shrubs. The exceptions are spring-flowering shrubs such as lilacs.
* Now is the time to prune fruit trees. Clean up leaves and debris around the trees to prevent the spread of disease. (The exceptions are apricot and cherry trees, which are susceptible to a fungus that causes dieback if pruned now. Save those until summer.)
* Prune roses, even if they’re still trying to bloom. Strip off any remaining leaves, so the bush will be able to put out new growth in early spring.
* Clean up leaves and debris around your newly pruned roses and shrubs. Put down fresh mulch or bark to keep roots cozy.
* When forced bulbs sprout, move them to a cool, bright window. Give them a quarter turn each day so the stems will grow straight.
* Browse through seed catalogs and start making plans for spring and summer.
* Divide daylilies, Shasta daisies and other perennials.
* Cut back and divide chrysanthemums.
* Plant bare-root roses, trees and shrubs.
* Transplant pansies, violas, calendulas, English daisies, snapdragons and fairy primroses.
* In the vegetable garden, plant fava beans, head lettuce, mustard, onion sets, radicchio and radishes.
* Plant bare-root asparagus and root divisions of rhubarb.
* In the bulb department, plant callas, anemones, ranunculus and gladioli for bloom from late spring into summer.
* Plant blooming azaleas, camellias and rhododendrons. If you’re shopping for these beautiful landscape plants, you can now find them in full flower at local nurseries.
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