Peach Twig Borer
Hosts
Apricot, nectarine, peach
Biology
In spring, the brown larvae emerge from protected cells on the limbs of trees, and tunnel into succulent shoot tips where they soon pupate to adults. Later in the season (after shoot growth hardens off), larvae enter soft fruit.
Symptoms/Damage
Infested twigs wilt and die back and small masses of gum exude from tunnel openings; larvae typically enter fruit near the stem end, especially in fruits with split pits; frass is present at larval entries into fruit.
Monitoring
- Non-mating disruption: Hang pheromone trap with peach twig borer lure at 300 degree days after March 1 to record date of first moth flight (called biofix, when 2+ moths have been caught). Leave trap in orchard and check moth numbers weekly to monitor population throughout the season.
- Mating disruption: There are no special peach twig borer lures for monitoring orchards under mating disruption.
Treatment Threshold
Usually treatment is always needed throughout the season; no threshold has been determined for peach twig borer under conventional management or mating disruption.
Degree Day Model
- Upper threshold: 88°F
- Lower threshold: 50°F
| Event | Degree Days |
|---|---|
| 5-28% egg hatch (1st gen) | 300-400 |
| 5-28% egg hatch (2nd gen) | 1200-1360 |
Management Considerations: Proper timing of insecticides is important. Utah offers spray timing dates, Colorado offers fruit information, and Idaho offers the Pacific Northwest Pest Alert Network.
In addition, maintain proper sanitation by removing apple bins from the orchard and removing/mowing fallen fruit.