5 Signs It’s Time to Deploy Mating Disruption
Mating disruption works by interfering with adult mating, so dispensers need to be in the field before adults start to fly. Ontario’s agriculture ministry notes that mating disruption programs usually rely on applying pheromones before the first flight of the target pest in spring. Washington State University is more direct: late application reduces effectiveness, because the method provides no control once mating has taken place.
At the start of a new season, before any other measures are in place, these five signs appear roughly in order. The later the sign, the less time you have.
Degree-Day Forecasts Put First Flight Within a Month
Utah State University’s guide for peach twig borer recommends placing long-lasting dispensers about one month before the predicted first male flight, so the pheromone can fully saturate the orchard before moths emerge. First spring activity depends heavily on weather, so check the degree-day forecast every year instead of following the calendar.
When the forecast shows first flight is a month away, it’s time to get ready.
Buds Are Starting to Break
For European grapevine moth, University of California guidance says dispensers should be in the field just before bud break. In apples, North Carolina State University reports that overwintering oriental fruit moth adults typically begin to emerge near green tip, and that dispensers should be placed before first-generation adults emerge, no later than tight cluster.
When buds start to move, the pest is about to move too.
Overwintering Pests Are About to Emerge
Filbertworm overwinters as larvae and pupates in spring, with adults emerging from late May. Oregon State University recommends placing dispensers in early May, before the first moths take flight. The same logic applies in forestry: for spongy moth, the Minnesota Department of Agriculture explains that mating disruption targets adults and is applied once, just before adults start to emerge in late June to early July.
Dispensers need to be in place before overwintering pests become moths.
Evening Temperatures Reach About 17°C (62°F)
For codling moth, UC IPM’s apple guidelines define the start of sustained flight by two conditions: moths found in traps on three consecutive checks, and sunset temperatures reaching 62°F (about 17°C). West Coast Nut describes the same temperature condition for codling moth in walnuts. This figure applies to codling moth only.
Once evenings warm to this level, the conditions for flight are in place.
Your Traps Catch the First Moths
This is the last signal. For oriental fruit moth, UC IPM advises applying mating disruption as soon as moths begin to emerge. The same holds for codling moth in pears: dispensers go up at the start of sustained flight, early enough to disrupt overwintering moths as soon as they emerge.
The day your traps catch the first moths is your deadline.
