What is in this article?:
- Leafminer, shuckworm pests target New Mexico pecans
- Hickory shuckworm
- HSW management
- New Mexico pecan growers and consultants are on high alert after a new leafminer pest species was found last year along with the reappearance of the hickory shuckworm insect.
- The pecan serpentine leafminer creates winding tunnels inside pecan leaflets which can result in tattered foliage when the mines dry and break apart in the wind.
- Pecan serpentine leafminer will likely be a very minor pest in New Mexico pecans.
- Nuts affected by the hickory shuckworm look like hailstorm damage occurred.
The other pest now on the New Mexico pecan radar screen is the hickory shuckworm (HSW). The pest was found late last summer in the Roswell area after a nearly 20-year hiatus. Alert scouts found black spots, blemishes, and bruises on the outside shucks and numerous small, white caterpillars tunneling inside the shucks.
“The nuts looked like they’d been through a hailstorm,” Sutherland noted.
The pest was found in 100 to 150 acres of commercial pecans. Inside a single shuck, Sutherland found 30 to 35 crawling caterpillars and narrow diameter, winding trails through the dried, blackened shucks plus the remains of two pupa cases typical of the caterpillars.
Caterpillar chewing jaws tunnel into the shuck disrupting the flow of moisture and nutrients to the developing nut. Very immature nuts are lost while more mature nuts may remain on the tree. HSW damage to older nuts can produce sticktights and nuts that never produce a mature or dry kernel.
HSW was found in the early 1990s in backyard pecan trees in downtown El Paso, Texas and then in the Mesilla Valley. HSW was also found in commercial and backyard pecan nuts in Chavez, Eddy, and Lea counties, but populations dwindled for unknown reasons by the mid 1990s.
HSW is a native insect found mostly in the eastern U.S. pecan-growing region from central Texas, Oklahoma, and Kansas to the Gulf Coast, Georgia, and South Carolina. HSW is a potential serious pest of pecan nuts, second to the pecan weevil, in those areas.
Sutherland said, “Hickory shuckworm has the potential to decrease pecan nut quantity and quality although its predictability and economic impact seem sporadic now in New Mexico.”
As with the pecan leafminer, HSW has a complete metamorphosis. Pheromone traps do not work well for shuckworm and many other species of small, look-alike moths.
More than 200 pesticides including 50-plus active ingredients are registered in New Mexico. Producers should check product labels already used for pecan casebearer control to determine if HSW is also included.
The adult HSW is dark gray to smoky black in color with a half-inch wing span. At rest, the insect is about three-eighths inches long with the wings held tightly against the abdomen.