2019 Volume 61 Pages 23-29
Young shoots infested with mulberry tiger moth larvae Lemyra imparilis (Lepidoptera: Arctiidae) were observed on ‘Delaware’ grapevine in an open field in April 1997 and 1998. Larvae primarily fed on leaf tissue, and damaged leaves were observed in 89.4% of infested shoots. Additionally, damage due to feeding was observed in 42.6% and 38.3% of infested flowers and shoot tips, respectively. In 27.7% of infested shoots, larvae consumed all 3 tissue types (leaves, flowers, and shoot tips).
The effects of feeding damage were evaluated by investigating growth and fruit characteristics of: 1) shoots with natural injuries due to larval moth infestation and 2) shoots with artificial injuries due to manual excision. Shoots that were missing all their leaves had reduced numbers of berries per bunch. However, many of the shoots infested with larvae only had partial leaf damage. These shoots could be used for normal fruit production, because there were no observed effects on shoot growth or fruit characteristics. Shoots with flower damage caused loss of part or whole of the fruit bunches. Shoots damaged at the tip could produce bunches; however, growth was markedly reduced, so they could not be used for fruit production the next season. Therefore, shoots with flower and shoot tip damage should be removed by suckering early in the season.
