Dr. Vaughn Walton, Associate Professor, Department of Horticulture, Dr. Nik Wiman, Assistant Professor Sr. Research, Department of Horticulture, OSU, Daniel Dalton, Faculty Research Assistant, Department of Horticulture, OSU
Brown Marmorated Stink Bug, (BMSB) is an invasive pest that has spread significantly throughout Oregon’s Willamette Valley. Since 2012, BMSB has increasingly been encountered by growers and can be found in wine grape vineyards of the Willamette Valley during the harvest period (Wiman et al. 2014), and established populations of BMSB are now found within the boundaries of nearly all Oregon AVAs. The highest risk areas include the Chehalem Mountains, Dundee Hills, Eola-Amity Hills, and McMinnville AVAs, although the risk is also increasing in AVAs located in southern Oregon and the Columbia Gorge. BMSB feed on vegetative tissues and grape berries, potentially causing contamination of wine grapes and wine quality losses. BMSB may be moving into wine grapes late in the season because other food sources become unavailable and population levels are at their peak. BMSB also display “hilltopping” behavior in the fall, where they may aggregate at relatively high elevations for overwintering. Unfortunately, this means they will encounter vineyards and wineries. Winemakers have reported infestation of winery buildings and finding dead BMSB in fermenting wines.
Brown Marmorated Stink Bug can develop on a wide range of host plants, meaning that it can find refuge or reproduce on non-crop hosts and then spread to cultivated crops such as wine grapes. Often, BMSB can be found along vineyard borders that have host plants such as bigleaf maple, Himalayan blackberry, Oregon ash, or other species that produce abundant seeds or fruits. Fruit feeding by adult BMSB may cause direct crop loss due to berry necrosis (VMW, SCRI CAP grant report 2013). Contamination of grape clusters and taint because of BMSB defense chemicals is also concern. These taints can be persistent, and may result in market losses. Work conducted on Pinot noir has shown that trans-2-decenal, a defense compound produced by BMSB, is a contaminant present in wine that is processed with BMSB.
Populations of BMSB have continued to grow unabated, with major increases over the past two seasons because of increased distribution and long growing seasons. The extra heat units during the growing season allow more of the nymphs to reach the adult stage and then fly to overwintering sites. Furthermore, lack of cold temperatures in winter has limited mortality. BMSB pressure is predicted to increase in 2015 over levels seen during 2014. Growers are encouraged to learn to recognize BMSB to be aware of potential damage or contamination risk during the harvest season. BMSB can be scouted by visual observation of clusters with efforts concentrated on borders. Despite availability of commercial products, traps are not encouraged at this time because of lack standard monitoring protocols and inability to link trap captures to meaningful damage thresholds.
Spotted Wing Drosophila, Drosophila suzukii (SWD), is firmly established in most Oregon vineyards (Loriatti et al. 2015). D. suzukii contributes to spoilage of wine grapes, but only under certain conditions. Our studies have shown that wine grapes are less suitable than fresh berry crops as a reproductive host for SWD. Wine grapes damaged by pre-harvest rains, birds or fungal infection are attractive to SWD, and when high population levels coincide with split grapes, SWD can affect quality of wine grapes by acting as a vector of Acetobacter spoilage bacteria.
The lack of winterkill and seasonal population models indicate that SWD will be present at high levels during harvest in 2015. Growers should be aware that conditions suitable for vectoring of spoilage bacteria may result in an economic impact by SWD during harvest of 2015.
References
Ioriatti C., V. Walton, D. Dalton, G. Anfora, A. Grassi, S. Maistri and V. Mazzoni. 2015. Drosophila suzukii (Diptera: Drosophilidae) and its potential impact to wine grapes during harvest in two cool climate wine grape production regions. Economic Entomology, 10.1093/jee/tov042.
Wiman N.G., V. M. Walton, P. W. Shearer and S. I. Rondon. 2014. Electronically monitored labial dabbing and stylet ‘probing’ behaviors of brown marmorated stink bug, Halyomorpha halys, in simulated environments. PLoS ONE 9(12): e113514 doi:10.1371/journal.pone.0113514.
