Apple Tree Pest Control: Spray or Bag?
We sell fruit trees here at Johnson's Nursery. Often when someone buys an apple tree, they ask about what to do to control pests. Rightly so, as many insects seem to enjoy feeding on the apple fruits as much as people do. The big fungal issue to control is apple scab, although a few other lesser fungi can cause problems too.
One way to get good pest control is to use pesticides. The key is to apply them at the appropriate times to get good results. Since monitoring insect/disease levels is a bit more time consuming than most home orchardists are capable of, they often use a basic pesticide spray program. Following this basic spray chart offers a broad control window by coating the fruit/leaves at all times to prevent pest issues.
Usually, a “Home Orchard Spray” is used, this is a concentrate of both fungicide and several insecticides. I prefer purchasing the fungicide Captan 50 WP and an insecticide Malathion separately for better pest control. Both these pesticides are compatible, so they can be mixed together in the same spray tank when applying.
Early in the season, no insecticide is needed. Only a fungicide is necessary for apple scab prevention. With the Home Orchard Spray, the insecticides are already in the mix and thus must be included in the spraying when not necessary. Another issue is that Home Ochard Spray also contains Sevin insecticide. Sevin cannot be applied at Petal Fall stage (important spray time against plum curculio) as it acts as a fruit thinner on newly formed apples and will cause many of the fruits to abort from the tree. Most Home Orchard Spray mixes will have a warning on them not to use the product from Petal Fall stage until the apples are about 1” in diameter to avoid this issue.
Paul’s basic apple spray chart:
- Leaves open 1/4”-1/2”........spray Captan fungicide........apple scab prevention
- 7 days later........spray Captan fungicide........apple scab prevention
- Petal Fall (defined as ¾ of petals have fallen off tree)........spray Captan + Malathion........scab, curculio, leafroller
- 7 days later (first cover spray)........spray Captan + Malathion........scab, curculio, leafroller
- 7 days later (second cover spray)........spray Captan+ Malathion........scab, curculio, leafroller
Continue spraying Captan + Malathion every 7 days up to June 15th. Since Primary Scab period is now over and curculio season is winding down, we can switch to summer spray program:
- June 15th-August 15th........spray Captan + Malathion every 10-12 days to control scab, apple maggot, coddling moth.
Sometimes home orchardists do not want to use chemical controls and ask me what they can do organically to get good apples? The answer is to bag them! Bagging works great for those who only have 2-3 trees. It would be too time consuming to bag all the fruit if many trees are involved. Bagging does provide great control on apple pests provided they are bagged prior to being damaged by insect or disease.
The Japanese have been growing great apples in bags for many years. They use somewhat expensive paper bags or re-usable cloth bags. The least expensive method is to use plastic ziplock sandwich bags.
1. Use scissors to cut the corners off the bottom of the bags. This is necessary for water to drain out. Be careful to cut just the tip of the
corner off only. Too big of a hole will allow insects to get in.
2. Next cut off the pull tab above the zipper. This tab will funnel water into the bag so must be removed.
3. Cut a vertical slit thru the center of the zipper to allow room for the apple stem.
4. Grasp plastic at above cut made for apple stem and carefully pull ½ of the zipper open. Leave other ½ of zipper shut.
The above steps can be done ahead of time indoors. Once the apples grow to about the diameter of a dime, they should be bagged as soon as possible. Place the bag over the apple and center the apple stem into the slot that was cut out of the zipper. Zip the zipper shut. The apple will grow and color well inside the plastic bag. No need to remove the bag until the apple is picked! Cheap and effective, bagging is organically growing apples in the simplest method.
Paul Schwabe is a salesman in our Contractor Sales division. He holds a degree in horticulture and will be writing about some of his favorite and underused plants.