Grease is a popular means of apple and fruit tree pest protection in general in the United Kingdom. Since neither apple trees nor the pests that grease protects against are limited to the U.K., the use of grease may benefit other orchard keepers wherever such pests are a problem.
Grease is a popular means of apple and fruit tree pest protection in general in the United Kingdom. Since neither apple trees nor the pests that grease protects against are limited to the U.K., the use of grease may benefit orchard keepers wherever such pests are a problem.
Grease suitable for fruit tree application comes in three types. The Royal Horticultural Society advises using grease bands on younger trees with smooth bark. These are essentially sticky pieces of paper that wrap around the trunk of a tree. For more complete application on older trees with cracked bark with fissures to protect, the RHS suggests using either of the other types, grease applied directly or insect barrier glue.
Wingless female moths emerge from the ground in November in the northern hemisphere, so the RHS advises applying grease in October for best protection. Grease should be left on apple trees until April, since some types of moths may still emerge throughout that time period. All three types of grease should be applied approximately 18 inches above the ground.
Depending on weather conditions, greases may need to be reapplied over the course of a single winter. Orchard keepers should check their applications regularly to make sure they are still effective. Grease traps wingless moths, stopping them from climbing the rest of the way up apple trees, which provides one visual cue that grease is working. If foliage is low enough, orchard keepers should examine their trees closely to look for eggs or other notable abnormalities.
While grease provides protection against the wingless types of female moths, it does not provide any protection against any types of moths that can fly. Flying moths have no need to climb past the grease, and have no chance of getting caught in it. Orchard keepers should apply other methods of pest control that are directly targeted toward these moths if they are a problem.