Issue link: http://read.dmtmag.com/i/89919
Brown marmorated stinkbugs (above) feed on grapes by piercing the fruit, injecting saliva, and then sucking up plant fluids. Feeding damage continues from fruit set through harvest. Brown marmorated stinkbugs can be seen in this red wine must (left). The inoculated white musts were pressed, cold settled, and fermented. The inoculated red musts were cold soaked for four days, and then fermented. Brown mar- morated stinkbug were very visible during punch downs. Unfermented juice samples were taken for testing. In 2011, the treatment was increased to 50 BMSB adults per lug, again compared to an uninoculated control. The juice samples were evaluated by many profession- als (including research entomologists), certified wine judges, and lay volunteer "judges" who were familiar with PRODUCTION SAFETY Vineyard & Orchard Production & Processing… Clothing, Sanitation and Processing Equipment, Industrial and Products, Farmworker Protective Spray Industrial Safety, Fire Protection and PPE Specialized Gases. Serving all of the Inland Northwestern Agricultural Industries PASCO: 509-547-2494 the BMSB aroma. A few could detect the taint in the juice at one insect per lug but a comparable number also thought they detected it in the control, therefore that was considered just background noise and not correct identi- fication. However, a majority could detect the taint in the juice at five and ten per lug relative to the clean juice. Test- ing samples over time has shown that the taint in the juice was perceptible for about four months. Good news And now the good news. The wines resulting from fer- mentation of the inoculated juice/must was similarly compared to controls, and, overall, there was no detectable taint in the white or red wines. In various tests, including the typical triangle comparison, there was no consistent recognition of wine made from the inoculated juices versus the control. Even in the second year, there was no clear taint perceived in wine directly inoculated with 50 BMSB per lug. The conclusion from these early studies is that percep- tible taint in the juice has not resulted in a perceptible sensory taint in the wine after fermentation. Currently, the wines are being tested for the presence of the com- pound to determine whether it can be in a latent or unde- tectable form that could later volatilize. However, the chemists I have queried have concurred that based on the chemistry of decanal, it should not be stable through fermentation or over time in a wine (alcohol) environment. Summary The future outlook for the brown marmorated Call your local OXARC® sales representative today! YAKIMA: 509-248-0827 MOSES LAKE: 509-765-9247 WENATCHEE: 509-662-8417 OKANOGAN: 509-826-3205 WALLA WALLA: 509-529-3060 46 NOVEMBER 2012 GOOD FRUIT GROWER stinkbug is uncertain, but it is reasonable to assume that populations and damage will increase over time and it will be a serious economic pest in agriculture. It can cause yield loss via direct damage to grape berries and induce fruit rots, depending on the population. Thresholds for economic damage are a significant part of the current research. But the good news is that inadvertent inclusion of some brown marmorated stinkbug during crush does not seem to result in taint of the wine. So, relax and enjoy a good glass of wine—preferably the uninoculated type! • Joseph Fiola is viticulture and small fruit specialist with University of Maryland Extension, Keedysville, Maryland. www.goodfruit.com