Fruit IPM Factsheet Fruit IPM Factsheet Buying & Using Insect Traps
By: Bill Shane, District Horticulture Agent, SWMREC
A useful way to time insecticide sprays is the use of pheromone traps and degree day models. Degree days use temperature data to predict insect, disease or plant development. Many plants have little growth below 42oF, for insects 50oF is the common threshold for activity. Degree days calculate the activity of a living organism using air temperatures. Electronic weather stations will provide degree day information. Maximum/minimum thermometers plus conversion tables from Michigan State University Extension can also provide degree day information. The MSU Crop Advisory Team Alerts (CAT) provide degree day information during the growing season. The CAT Alerts also provide helpful reminders throughout the growing season.
It is important to monitor orchards on a regular basis (at least weekly during the growing season) to verify that insect activity is as expected. The amount of time needed to scout an orchard depends on tree density, growth stage and the experience of the observer.
The Pheromone traps use a synthetic insect attractant in a capsule or other form to lure male moths to a sticky surface. The traps plus the degree day models help the fruit producer to decide when sprays are needed. Pheromone traps help the orchard manager determine when moth flights begin, reach their peak and end. There are numerous distributors of pheromone traps.
For Apples: pheromone traps are most useful for the codling moth, oriental fruit moth ,spotted tentiform leafminer, apple maggot and obliquebanded leaf roller. Some people also trap for red banded leafroller, tufted apple bud moth and lesser apply worm but these are minor pests for Southwest Michigan.
For Peaches: pheromone traps are recommended for monitoring oriental fruit moth. It is debatable whether or not trapping for lesser and greater peach tree borers is needed for timing trunk sprays.
For Tart Cherries: as with apples, yellow sticky boards, and sticky red balls are useful for timing sprays for cherry maggot.
General Trap Operating Procedure: Never touch the capsule with your fingers. Use tweezers to
put pheromone capsule in the traps. Traps should be put on the south side of trees at eye
level. Mark trap locations with flagging tape (pink works well), including bands around
the base of the tree. Traps should be 30 or more feet apart. Insect picture fact sheets
are available from the suppliers listed at the end of this article. An excellent source of
pictures and descriptions can be found in the 1993 book "Common Tree Fruit
Pests", by Angus H. Howitt available from Michigan State University Extension.
Pheromone capsules should be changed every month. The sticky traps should be changed
whenever debris reduces the "stickiness". A general rule of thumb is 2 pheromone
traps per block, with a minimum of 1 trap per 10 acres. Put a least one trap on the side
of the orchard facing abandoned trees and hedgerows.
Specific Pest Recommendations
Codling Moth: put
out traps at tight cluster to pink, approximately April 15. When trap catches are 2 to 3
codling moths per trap - we call this the biofix, around mid to late May. Time sprays for
hatching larvae at 250 degree days base 50 after biofix the first or second week of June.
A second spray 10 to 13 days after the first may be needed for sites with high codling
moth pressure. Codling moth entries into apple fruit are seen about mid June.
Pheromone capsules should be changed at the end of June, to detect the new flight in July.
Larvae from the 1st generation will mature, pupate, and hatch resulting in moth catches
about the end of June to early July, about 1200 degree days from the biofix in May. Sprays
for this new crop of larvae are applied about 1400 degree days base 50 from the May
biofix, before emergence.
Oblique Banded Leaf Roller: This
pest overwinters as half developed larvae. Put traps into orchard at tight cluster growth
stage, about April 15. Traps are used to detect 1st generation adults in the spring, with
significant catch (biofix) occurring about the 1st or 2nd week in June. Typically,
insecticide programs in pink and petal generally controls the first generation.
Traps and pheromone should be replaced about June 1, to detect 2nd generation adults.
About 600 degree days base 42 should elapse between first catch of the 1st generation
moths and insecticide treatment about the first week of July. Larvae feeding damage is
usually seen about mid July. Once the larvae are big enough to be seen they are difficult
to control.
Oriental Fruit Moth: Over
winters as full grown larvae. Put traps into orchard at tight cluster (apple), about April
15. Traps are used to detect 1st, 2nd and 3rd generation adult flight.
First generation, time insecticide sprays for hatching larvae at 200 degree days base 42
beyond the point when accumulated trap catches of adult male moths are more than 1
oriental fruit moth per trap, approximately the 1st of June, followed by a second spray
200 degree days base 42 after that. On peaches, the first sign of larval activity is the
flagging of peach terminals due to the burrowing larvae.
Adults of the 2nd generation appear about the end of June. Damage appears about 10 to 14
days after emergence. Use the adult emergence date as the biofix and spray 200 degree days
base 42 after the first.
Oriental fruit moth has a third generation that can be a problem on late apples. Monitor
and spray when trap counts become greater than 8 oriental fruit moths per trap per week.
The need for sprays for other pests such as apple maggot late into the season may also
enter into the decision process.
Use of pheromone traps and degree day models is a more precise way to tailor insecticide sprays to the year and orchard. Experience is the best guide for the use of these tools.
