Managing Vineyard Insect and Mite Pests
Grape Tumid Gallmaker
The grape tumid gallmaker (Janetiella brevicauda) is a pest native to the northeastern United States and southeastern Canada. It infests only wild and cultivated grapes (Vitis spp.).
Symptoms
Larvae cause injury by boring into vine tissue and causing a round, reddish gall to form (See Figure 22.16).
Life Cycle
From early spring to late summer, it lays its eggs in masses within the unfolding buds or shoot tips. Maggot-like larvae hatch from these eggs and enter the vine tissue (See Figure 22.17).
Monitoring
The best approach in monitoring this insect is to check for the presence of eggs within the unfolding buds or shoot tips. It can be difficult to identify positively the adults because of the large number of similar midges in North America.
Cultural Pest Control
Growers might also consider burying the pupae by mounding soil up under the vines early in the season.
Biological Pest Control
There are several parasitic and predatory species of insects that attack the larvae of grape tumid gall midges. See Appendix J, Beneficial Insects, Mites, and Spiders.
Chemical Pest Control
Standard chemicals for controlling grape tumid gallmaker include Danitol (fenpropathrin) and Movento (spirotetramat). Insecticides used for controlling grape tumid gallmaker in vineyards are presented in Appendix K, Insecticides Registered for Use in Vineyards.
Applying Control Materials
Insecticide applications are not economically prudent unless the infestation is heavy or the vineyard has a history of tumid gall problems. Treatment, when economically justified, should be timed to kill adults of the overwintered generation as they emerge. In view of the difficulty in detecting the adults, it may be most feasible to base control measures on the first sign of larval entrance into vine tissues either by signs of small white scars or on the first indication of gall formation.
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