Attract-and-kill for managing Popillia japonica (Coleoptera: Scarabaeidae) abundance and leaf injury in commercial vineyards

Popillia japonica Newman (Coleoptera: Scarabaeidae) feeding negatively impacts many plant species, including grapes, potentially reducing fruit quality and yield. Chemical control, representing the current grower standard, relies on frequent broadcast applications of broad-spectrum insecticides, with alternative management strategies mostly lacking. Attract-and-kill (A&K) is a behavioral management strategy that combines semiochemical attractants and a killing agent on a substrate. This study assessed the impact of A&K on (i) the number of P. japonica adults and (ii) the percent of P. japonica feeding injury on grape foliage compared to the grower standard in commercial vineyards. This 2-year study was conducted at 3 commercial vineyards with 4 paired plots consisting of a grower standard control and an A&K treatment. The A&K treatment consisted of commercial lures, each placed on outside-edge grapevines, and weekly applications of carbaryl on the plants holding lures. The grower standard received broadcast insecticide applications at the grower's discretion. The A&K treatment experienced similar numbers of P. japonica adults and similar proportions of leaf injury compared to the grower standard. The use of A&K reduced by 96% the crop area treated with insecticides compared to the grower standard. The area treated by A&K was at the edge of the vineyards, where more leaf injury occurred regardless of treatment. A&K is a targeted approach that was effective at managing P. japonica and reducing chemical inputs on a small scale. It has the potential to be scaled up and refined to provide growers with a new management strategy.

Interactive effect of springtime frost and elevated ozone on early growth, foliar injuries and leaf structure of birch (Betula pendula)

•   Impacts of ozone and late frost on six birch (Betula pendula) genotypes from south-eastern Finland were studied in an 8-wk chamber experiment. •   The plants were measured for bud burst, growth, visible foliar injuries caused by ozone and frost, structural leaf properties and changes in chloroplasts. •   Ozone delayed bud burst but stimulated subsequent growth. Acute frost injuries were compensated by increased leaf production. Early bud burst predisposed to frost damage, whereas late bud burst increased the vulnerability to ozone. In combined ozone + frost treatment, freezing reduced visible ozone injuries, counteracted ozone-induced growth enhancement and stomatal changes, and exacerbated ozone-caused reduction in palisade cell, chloroplast and starch grain size. Rapid changes in epidermal cell differentiation towards stomata and/or glandular trichomes occurred to enhance ozone/frost tolerance. •   The results showed large genetic variation within birch population in response to frost and ozone. Generally, birch seem to recover from acute frost occurrence efficiently through compensating leaf production, but co-occurring ozone enhancement may disturb the recovery processes mechanistically through structural damage in photosynthetic tissue, especially in chloroplasts.

Ozone exposure affects leaf wettability and tree water balance

•  Relatively little is known about the influences of growing-season background ozone (O₃ ) concentrations on leaf cuticles and foliar water loss. •  Using fumigation chambers, leaf wettability and foliar water loss were studied in two poplar species, Populus nigra and P. euramericana, and a conifer, Pseudotsuga menziesii, under three O₃ regimes; control (approx. 1 ppbv O₃ ), urban O₃ exposure (13-41 ppbv O₃ ), and montane O₃ exposure (30-45 ppbv O₃ ). •  Urban O₃ exposure delayed a decrease in droplet contact angles over time in Populus leaves by 2-4 wk, and decreased droplet contact angles of P. menziesii foliage. Ozone exposure increased foliar water loss and minimal conductance to water vapour for P. euramericana, but not P. nigra and P. menziesii. Both Populus species had lower photosynthetic biomass in O₃ treatments, due to production of fewer new leaves, premature leaf abscission and decreased leaf size (P. euramericana only). Leaf abscission was preceded by foliar injury symptoms characteristic of O₃ exposure. •  Results suggest that exposure to [O₃ ] common during the growing season can increase water loss in Populus saplings, but this effect might be offset by decreased foliar biomass. Importantly, responses were highly species specific in a given O₃ treatment.