|
|
|
| Hickory shuckworm | Hickory shuckworm | Hickory shuckworm |
Hickory shuckworm is an important, late-season pest of pecans throughout much of Texas.
Damage: Shuckworm larvae tunnel in the shuck, interrupting the flow of nutrients and water necessary for normal kernel development. Infested nuts are late in maturing, of poor quality and scarred. Damaged shucks stick to the nuts and fail to open, creating "sticktights" that reduce harvesting efficiency. Infestations occurring before shell hardening may cause nuts to fall.
Biology: The adult shuckworm is a dark brown to grayish-black moth about 3/8 inch long. Moths are active in the spring before pecan nuts are available. These moths deposit eggs on hickory nuts and on pecan buds. Larvae on pecan feed in phylloxera galls in the spring. Later in the season when pecan nuts are present, moths deposit their eggs singly on the nuts. The egg is attached to the shuck with a creamy white substance visible on the surface of the shuck. The egg hatches in a few days and the tiny larva burrows into the shuck to feed for about 15 to 20 days. Mature larvae are about 1/2 inch long, and cream colored with light brown heads. Pupation occurs in the shuck and the moth soon emerges. Several generations are completed each year. Shuckworms overwinter as full-grown larvae in old Pecan shucks on the tree or the orchard floor.
Control: Pecans are most susceptible to hickory shuckworm damage after the gel stage. If the orchard has a history of shuckworm damage, insecticide treatment should be made when pecans reach the half-shell hardening stage. A second application 10 to 14 days later may be needed. Removing and destroying old shucks and dropped nuts, in which shuckworms overwinter, can reduce shuckworm infestations.
Pheromone traps that attract and capture hickory shuckworm moths are available commercially. Guidelines for using trap catches to determine the need for treatment have not been validated in Texas.