When to Spray Wisconsin Apple Trees

Apple trees are the most common fruit tree grown in Wisconsin.

Problem insects and diseases of Wisconsin apple trees are aphids, apple maggots, codling moths, apple scab and fire blight. Identifying and controlling apple tree pests and diseases are important for a healthy crop.

Prevention

The preventative program of spraying uses three to four insecticide sprays per year. The first spray is to be done at petal fall and the second spray is done two weeks after the first spray. Subsequent spraying is done in mid-July and early August.

Considerations

According to the University of Wisconsin Extension, trees that have a high number of insects should be thoroughly sprayed at 10- to 14-day intervals. Spraying is to begin at petal fall and extend through August or early September.

Alternatives

The curative method of spraying Wisconsin apple trees involves learning how to recognize and monitor common pests and diseases by using pheromone traps, sticky traps and visual inspection. When using this method, trees are sprayed only when necessary.

Warnings

Reapply spray if rain falls within 12 hours of application. Wet all foliage thoroughly with spray until spray drips off leaves. Do not apply pesticides during bloom, as pollinator insects are necessary for fruit set. Read and follow pesticide instructions before applying.

References

• University Of Wisconsin Extension: Growing Apples In Wisconsin
• Vilas County Land and Water Conservation Committee/Department: Apple pest management for home gardeners

Resources

• Iowa State University Extension: 2010 Midwest Tree Fruit Spray Guide