Pfeiffer, D. G.2008.Major
insect and mite
pests of grapes. p. 241-261, 307-311. In: T. K. Wolf (ed.) Wine
Grape
Production Guide for Eastern North America.Natural Resource, Agriculture, and Engineering Service,
Cornell.
Galls of various shapes occur on grape as a
result of attack by small gall midges. Galls occur on leaves, tendrils, blossom buds and in the rachis, and can occasionally
cause considerable injury. Galls on the leaf blade may occur in
clusters, and contain a single orange maggot each. Other
galls, in the rachis for example, may contain a network of
tunnels. Numerous species of gall midges attack grape. The
main species is the grape tumid gallmaker, Janetiella brevicauda, formerly called tomato gall,
and also formerly thought to be a complex of several species.
Infestations in the rachis are more damaging than foliar, petiole
or tendril galls, because they can lead to failure of clusters to
to develop. Some varieties (e.g. Traminette, Niagara) are
more sensitive than others. In most situations, pesticide application is not
required because there is little economic impact from low to
moderate levels of galls. In blocks with a
history of high populations, however, Movento (spirotetramat) may
be used, timed to the first appearance of galls. This is
included under the Pre-bloom section in the Virginia Tech Pest
Management Guide for Commercial Vineyards. Removing
the galls by hand and destroying them would inhibit future
populations.
