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Fruit trees and ornamentals
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Do I need to spray my fruit trees, roses, berries, and grape vines? How about ornamental trees?
Yes, yes, yes, and yes.
Dormant sprays containing
help prevent many of the diseases we see each spring, including peach leaf curl, powdery mildew, shothole fungus, and brown rot on stone fruits (peaches, nectarines, plums, cherries...).
help to smother overwintering insect pests, and help the spray stick to the trees. Some other products may help the spray stick even better, and should be used when rain is likely soon after spraying.
that are related to fruit trees should also be sprayed -- flowering plums, pears, crabapples, etc.
What should I spray on my fruit trees this winter?
Liquid copper or copper soap.
Copper sulfate and lime sulfur, two older materials formerly used as dormant sprays, are no longer available.
dormant spray oil
can be added to either material in the same spray mix.
When should I spray?
Do you mean "
what time of year
The old rule of thumb is:
Thanksgiving, Christmas, and Valentine's
. The one to skip, if your time is limited, is the Christmas spray -- that is the least important of the three.
This schedule works, except that if brown rot of stone fruits has been your big problem (as it's been in the two very wet springs of 1997 & 1998!) an additional spray while the tree is in bloom is important.
Do you mean "
should I spray today
?" or "
does it matter if it's going to rain soon?
If it rains within 24 hours of spraying you should spray again.
What will happen if I don't spray my trees?
Certain disease problems, especially
peach leaf curl and brown rot
, will get worse year after year, especially on older trees and if we repeatedly have wet springs. If your trees are young you can get by without spraying for a few years.
Healthy, vigorous peach and nectarine trees will outgrow the spring infection of peach leaf curl, even if every leaf has been affected. The disease doesn't affect the fruit of peaches, though bumpy infections on nectarines have been reported.
Brown rot on apricot will get worse from year to year. In a wet spring, nearly all of the blossoms may be infected, leading to very poor fruit set and low yields.
Will dormant sprays help prevent the worms in my apples or cherries?
. For apples, you need to spray a pesticide (organic or otherwise) to kill the codling moth adults before they lay their eggs, which happens just as the tree is finishing blooming. Dormant sprays will help prevent diseases on apple trees.
We don't presently have an effective remedy for the
Spotted wing drosophila
that is infesting the fruit of sweet and pie cherries. Dormant sprays will not have any effect on them.
How poisonous is this spray?
The liquid copper sprays are low toxicity. The dormant oil is very low toxicity. Copper soap is approved for use by certified organic growers.
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© 2008 Don Shor, Redwood Barn Nursery, Inc., 1607 Fifth Street, Davis, Ca 95616
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