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Plant disease-resistant apple varieties
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July 12, 2006
MILTON-FREEWATER - Are you thinking about planting some new apple trees on your property this winter or spring? If you want to apply chemicals to control apple diseases, your best bet is to plant disease-resistant varieties.
In western Oregon, apple scab is the apple disease that requires the greatest number of fungicidal sprays for control. An alternative to using fungicides is to plant scab-immune varieties, explained Tom Darnell, horticulturist with the Umatilla County office of the Oregon State University Extension Service.
Since 1985, OSU has tested scab-immune and scab-resistant apple varieties at their experimental farms in Corvallis. The trees received no fungicide applications. The following apple varieties showed no symptoms of apple scab infection, plus had good flavor:
- Redfree - a medium-small crisp, sweet red apple that matures in late August.
- Priscilla - a small, part red apple that matures in mid-September.
- Nova Easy Gro - a medium, dull-red apple that also matures in mid-September.
- Liberty - a medium red very firm apple that matures in early October. Rated as having the best flavor of all the apple-scab immune varieties.
Also, the apple cultivars Akane (Tokyo Rose), Chehalis, Prima, Spartan and Tydeman Red have shown good resistance to scab and good quality in our region, according to the 2004 PNW Plant Disease Management Handbook, edited by OSU Extension plant pathologists.
In eastern Oregon, fire blight on apples is the major problem on apples. Susceptible varieties include Gala, Fuji and Braeburn, said Darnell.
According to the 2004 Pacific Northwest Plant Disease Control Handbook, the following apple varieties are resistant to fire blight: Liberty, Northern Spy, Prima, Red Delicious, Redfree, Spur Delicious, Stayman Winesap.
"Fire blight isn't usually a problem every year in eastern Oregon, but when it hits it is very damaging and almost impossible for the homeowner to control or manage," said Darnell.
For more information, the OSU Extension and Experiment Station website offers for no charge, a four-page circular, "Scab-immune apple varieties for new orchards," by Robert L. Stebbins, OSU Extension horticulture specialist emeritus. The publication talks about prevention of apple scab, origin of scab-immune varieties, and detailed descriptions of 11 apples varieties found to be immune to apple scab in Corvallis.
For more information on "Scab-immune apple varieties for new orchards," EC 1334, visit our on-line catalog. Our publications and video catalog at: http://extension.oregonstate.edu/catalog/ shows which publications are available on the Web and which can be ordered as printed publications.
Source: Tom Darnell