Dealing with cedar apple rust
Published 8:15 am Wednesday, May 23, 2018
Have you looked at your apple trees lately? You may have noticed some odd-looking yellow spots on the leaves.
Earlier in the spring, you may have noticed some alie- looking structures on cedar trees.
Those were the structures where cedar apple rusts could have originated.
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It is too late to do very much about cedar apple rust on your trees now, but here is a little more information about this disease.
Cedar apple rust fungal infection appears in mid-spring on cedar trees. As spring progresses, the basidiospores travel by wind from cedar trees and infects apples trees.
Basidiospores can cause infections during relatively short periods of wetness (about six to seven hours) when temperatures are in the 50- to 60-degree Fahrenheit range.
Cedar apple rust is the most common rust disease occurring on apples in Kentucky.
The infections begin as small, pale yellow spots on upper leaf surfaces. The yellowish-orange spots will enlarge and will be surrounded by a reddish border. You may also notice on the underside of the leaf, a ring of brown spores.
Leaf spots develop on the upper of the leave surfaces about 10 to 14 days after it becomes infected.
On the fruit you will notice more infection around the blossom end. These will be similar to what you notice on the leaves but much larger.
Danger of infection usually extends from leaf expansion and pink bud stage.
Methods of preventing and controlling this disease include choosing varieties resistant to cedar apple rust or applying a fungicide such as Mancozeb or Immunox on a preventative basis.
On the positive note, the rust will only last one season.
This disease can reoccur year after year, weakening the trees over time.
If you have any questions about cedar apple rust or have other questions regarding your fruit trees, contact the Clark County Cooperative Extension Service by calling (859) 744-4682.
Kendal Bowman is an agriculture and natural resources summer intern with the Clark County Cooperative Extension Service.