Cranberry Girdler

CRANBERRIES

Cranberry Girdler
Order: Lepidoptera || Family: Pyralidae
Chrysoteuchia topiaria (Zeller)

Adults:

Adult moths are active in Maine from late June through the end of July, and they make short, jerky flights upon being disturbed. There is a pheromone trap that is used for monitoring them, and the numbers captured in the eastern part of Maine during the 1997 growing season were considerably higher than was noted in 1996. The moth is small, 3/8 of an inch long, and silvery-white (almost snow-white) in color. It has a noticeable "snout" on the front of its head, and its wings have vertically streaking bands extending almost the entire length, met by some cross-bands near the tips. There is also a row of dots along the exterior margin of the forewings. The pheromone within the trap is quite specific to the girdler moth, and so very few other moths should be noticed.

Larvae:

The damaging stage of the cranberry girdler is the larval stage, as is the case for all of the primary moth pests affecting cranberries. The larvae feed on the roots and runners of the cranberry plants, sometimes chewing completely through a runner in a "girdled" (ring-like) fashion. They are hard to find because they remain concealed in the leaf litter at the base of the vines. But the evidence of their feeding is easy to note. As more and more roots and runners are severed, the plants begin to die, taking on a reddish-brown appearance that can be observed throughout August and September. One should pull back the vines in any suspected areas to look for girdled vines and small clumps of sawdust-like particles, which is their waste droppings. The larva is small, white and grub-like with an orange head. It also has very fine hairs scattered along its body that you may or may not be able to see upon first inspection.

CONTROL

There is no known action threshold for this pest, and control is difficult. There are a few cultural practices that can help a lot, however, such as regular sanding. Flooding the bed for six days in late September also helps to control the larvae. Properly-timed applications of parasitic nematodes is also a good control method. They should be applied early in the evening, 2 weeks after the end of moth flight, and then irrigated immediately. Excessive leaf trash can reduce nematode effectiveness.

If you have comments or questions about this page,
contact Charles Armstrong at: charlesa@umext.maine.edu

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These pages are currently being maintained by the Pest Management Office, University of Maine Cooperative Extension. Page Last Modified: 04/11/08