Conotrachelus nenuphar
Written by:
Jaime Pinero
Overview
Biology
-
Adult PCs typically overwinter in wooded lots adjacent to peach orchards or around fence rows from where they immigrate into peach orchards in the spring beginning around bloom.
-
Generally, commercial orchards do not have overwintering populations within their borders. Some studies, however, have shown that PCs can overwinter inside orchard blocks that are weedy in the fall. Wild hosts (abandoned orchards, crab apples, etc.) near orchards provide habitat that allows adult PC to migrate into orchards before and after bloom.
-
The female makes a crescent-shaped cut in the skin of the fruit and then lays eggs under the flap of skin. This results in D-shaped scars on the fruit surface. When eggs hatch, larvae tunnel into fruitlets and begin to feed. Larvae complete four instars inside the fruit in about 16 days. PC-infested fruitlets generally drop to the ground prematurely.
-
Larvae may feed on the fruit for 2–3 weeks before they burrow into the ground to pupate. Adults emerge in mid- to late-summer to cause more feeding damage on mature fruit before they overwinter.
Monitoring
- Fruitlets should be monitored beginning at about 5 mm diameter along orchard borders to determine if new injury is occurring. If fresh oviposition scars are observed, a first cover spray should be made to the entire block. Cool, wet weather will prolong PC activity.
- Continue to monitor for fresh scars. If more are found, a second cover spray targeting perimeter-row trees may be needed.
Management
-
Management of PC relies heavily on petal fall, first and second cover insecticide applications. The first insecticide application should be made to the whole orchard in order to control PC adults that have migrated into the inner part of the orchard.
-
Additional insecticide applications may be necessary and can be limited to the outer two rows of trees.
- Kaolin clay (Surround WP) is an OMRI-listed material that can also be complementary to conventional management strategies. Applied in suspension in water, kaolin clay produces a dry white film layer of interlocking microscopic particles on the surface of leaves, stems, and fruit after evaporation of the water. Kaolin acts as a physical barrier preventing insects from reaching vulnerable plant tissue. It acts as a repellent by creating an unsuitable surface for feeding or egg-laying.
Surround applications begin at Petal Fall and get reapplied weekly to maintain coverage and deter egg-laying.
Do not apply insecticides until bloom is completely finished to reduce unwanted pollinator exposure to insecticides.

