(117) Grape Cultivar Preference and Organic Control of Japanese Beetles (Popillia japonica)

Abstract

Feeding by Japanese beetles (JB) can damage grape leaves and result in a loss of vine leaf area, thus reducing both yield and fruit quality. The objectives of this study were to determine if there was a grape cultivar feeding preference by JBs and whether application of organic feeding deterrents to leaves would reduce damage by JBs. Eleven American and hybrid grape cultivars were evaluated in a choice feeding study in cages, where 15 JBs per vine were introduced for 48 hours. The number of leaves damaged by JBs varied by cultivar. `Chardonel' (43%) had fewer damaged leaves than `Seyval' (78%), `Edelweiss' (74%), `Norton' (63%), and `Vignoles' (63%). The leaf area lost by feeding varied by cultivar, with `Lacrosse' (15%) showing the least damage and `Seyval' the most (40%). In another JB choice feeding study with organic feeding deterrents, Surround (at label rate) and Neemix 4.5 [at high label rate (A) or doubled high label rate (B)] were compared to a water control with `Chardonel', `Traminette', and `Vignoles' grapes. Surround and Neemix 4.5 applied at level A reduced the number of damaged leaves compared to the control; however, Neemix 4.5 at level B showed similar damage to the control. Loss of leaf area due to feeding of JBs was greatest on vines treated with Neemix 4.5 at level B and least on those treated with Surround, although this loss of leaf area was not significantly different between the two Neemix 4.5 treatments. Vines treated with Surround had the least leaf area loss, followed by the control, Neemix 4.5 at level A, and Neemix 4.5 at level B.