Japanese beetle (Popillia japonica) control and varietal comparisons in primocane-bearing caneberries

In 2009, bioassays and field experiments were performed to determine how insecticides with low pre-harvest intervals and raspberry variety affected Japanese beetle (JB) (Coleoptera: Scarabaeidae) activity on primocane-bearing raspberries. JB causes both direct and indirect injury on primocane-bearing caneberries; adult JB commonly feed on berries in the harvest period, complicating chemical control. A bioassay illustrated that percent defoliation is reduced when leaves are treated with Chenopodium ambrosioides extract (Requiem), deltamethrin (Battalion), acetamiprid (Assail), chlorantraniliprole (Altacor), or a neem oil mix (Neemix and Trilogy). There was a higher JB mortality on leaves treated with Assail and Battalion. Also, after 48 hours there were fewer beetles present on leaves treated with Requiem, Assail and Battalion. Our results did not show varietal differences in percent defoliation among Prelude, Autumn Bliss, Fall Gold or Heritage leaves. In field experiments there were more beetles present on plants treated with Assail than the control and all other treated plants. JB counts were higher on Prelude and Fall Gold and lowest on Dinkum, Caroline, Heritage and Himbo Top. Treatments affected the grams of marketable fruit only on 10 August in which there was greater marketable yield from plants treated with Battalion. Raspberry variety affected the grams of marketable fruit on 6 August, 10 August and 13 August; later dates did not show significantly different yields of marketable fruit. The seasonal percent of marketable fruit was highest for the variety Autumn Bliss and lowest for the varieties Himbo Top and Caroline.