Integrated Pest Management Guide

CRANBERRY TIPWORM, Dasineura oxycoccana (Johnson)

Pest Status: This pest was found in cranberry in British Columbia for the first time in 1998. It is an increasing problem.

Life cycle and feeding habits: Tiny larvae develop through three instars: first clear, then light green, then orange. Larvae have no visible head and are no more than 2 mm (1/16 inch) long when mature. Orange third-instar larvae metamorphose into puparia, which are pink to tan or brown. Puparia enclosed in silk remain in the damaged tip on the vine or fall to the trash layer. Adults emerge soon after, then mate and lay eggs (35 - 45 per female) at the base of small leaves on the plant tip. The adult is a very small fly similar to a midge less than 2 mm (1/16 inch) long.

Tipworms have at least two generations in the Pacific Northwest. Puparia of the last generation spend the winter on the floor of the bed. Larvae use rasping mouthparts for extracting the juices from plant tips resulting in browning (or whitening) of the two uppermost leaves.

Monitoring: Injury caused by tipworm is often mistaken for fireworm or frost injury. The first sign of cranberry tipworm is a cupped leaf at the tip of a cranberry upright. Using a magnifier or dissecting microscope, inspect upright tips for maggots. Up to four larvae can be found feeding in the same tip.

Damage from the first generation of tipworms becomes visible in late May or June. The second generation attacks the tips in July. Early-season injury can cause lateral branching. Injury is more common on lush vegetative growth. However, uprights showing damage as late as mid-August may make a complete recovery in terms of flowering potential for the next season.

Control: In Massachusetts and Wisconsin, where tipworms are relatively common, entomologists have evidence that cranberry vines usually recover from tipworm attack and, therefore, rarely recommend insecticides for control of this pest. However, if there are other factors causing vine stress, tipworms may cause damage and a registered insecticide for control of tipworm may be recommended. The most effective time to treat infested fields is during peak egg hatch of the first generation. Peak egg hatch is determined by inspecting 50 - 100 uprights for recently hatched larvae. Vine tips must be dissected under a microscope to find tiny, clear or greenish white larvae. A new sample of uprights should be inspected at a safe interval after an insecticide application to look for dead larvae. This will determine if a second treatment is required. For best control, target first or second generation larvae during their early stages of development. Insecticides targetting orange larvae or pupae will be too late and ineffective.

Cranberry tipworm larva (photo courtesy of J.-F. Landry)	Cranberry tipworm puparia in cocoons
Cranberry tipworm male (photo courtesy of J.-F. Landry)	Cranberry tipworm female

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