Copper sprays can be effective if applied during dormancy
Distorted and blistered leaves are signs of peach leaf curl.
Now is the time to spray peach and nectarine trees to control
it. (Photo courtesy UC Statewide Integrated Pest Management)
It may be Thanksgiving, but it’s time to talk peaches. In particular, this conversation is about peach leaf curl.
This common fungal disease only attacks peach and nectarine trees. It distorts and puckers foliage and new shoots. It can completely defoliate a tree, leaving any developing fruit to sunburn or shrivel. Over time, it greatly cuts down on a tree’s productivity.
And it comes back, year after year after year. Once it’s established, peach leaf curl will be an issue every spring.
The time to combat this fungus is not when you see its damage in April or May; it’s now, in the days before and after Thanksgiving.
To control leaf curl, peach and nectarine trees benefit from dormant spraying with a copper fungicide or copper soap. Horticultural oil helps make that copper spray stick to the twigs and branches.
According to the UC Integrated Pest Management Program, the copper spray smothers the fungal spores that overwinter on the tree.
“The fungal spores that cause the disease spend the winter on twigs and buds and germinate in the spring,” say the IPM experts. “For effective control, treat trees just after leaves have fallen, usually late November or December.
"A second application in late winter before buds swell can be considered, especially in areas with high rainfall or during wet winters. Don’t apply fungicides during the growing season because they won’t be effective.”
A dry, calm and fogless almost-winter day; that’s the perfect time to spray. And that’s also the forecast for the greater Sacramento area this Thanksgiving weekend and early next week. Copper sprays need 24 hours of dry, calm weather before and after application. This is a good window of spraying opportunity.
If needed, prune before spraying. Pick up any dropped foliage and discard (don’t compost). Those fallen leaves may carry leaf curl, too.
For more on treating peach leaf curl: http://ipm.ucanr.edu/QT/peachleafcurlcard.html
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Dig In: Garden checklist for week of Jan. 29
Bundle up and get work done!
* 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, except apricot and cherry trees. Clean up leaves and debris around the trees to prevent the spread of disease.
* Prune roses, even if they’re still trying to bloom or sprouting new growth. Strip off any remaining leaves, so the bush will be able to put out new growth in early spring.
* Prune Christmas camellias (Camellia sasanqua), the early-flowering varieties, after their bloom. They don’t need much, but selective pruning can promote bushiness, upright growth and more bloom next winter. Feed with an acid-type fertilizer. But don’t feed your Japonica camellias until after they finish blooming next month. Feeding while camellias are in bloom may cause them to drop unopened buds.
* Clean up leaves and debris around your newly pruned roses and shrubs. Put down fresh mulch or bark to keep roots cozy.
* 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. Avoid spraying on windy days.
* 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 gladiolus 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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