Cracked berries: Grape powdery mildew on chardonnay berries with cracking of berries being a result of heavy infestation.
In the 1960s and 70s Oregon wine makers did something incredible. They began growing pinot grapes in the cold, wet climate of the Pacific Northwest, where it was previously believed they could not be produced. Since then, the Willamette Valley has come to prominence as one of the United States’ premier growing regions, with vineyards harvesting grapes for every kind of wine you can imagine.
However, there are serious challenges to the wine industry in Oregon. A fungus known commonly as grape powdery mildew, which plagues vineyards across the United States, is one of the main culprits. Unlike other places in the United States, the growing season for grapes is completely different in the climate of the the Pacific Northwest. In this environment, traditional strategies for protecting grape harvests from outbreaks of these fungal spores are not as effective.
This is where Lindsey Thiessen comes in. A PhD candidate in Walt Mahaffe’s Botany and Plant Pathology lab, Lindsey studies plant and fungal pathosystems. Pathosystems are the relationships between the disease causing agent (in this case, a fungus) and the host (in this case, the grapes). In order to protect the Oregon wine industry, Lindsey is learning about the ecology of grape powder mildew fungus and grape plants during ‘overwintering’, when the grape buds and fungus go dormant. Lindsey helped devise a spore trapping device for use in the growing season to provide valuable information on fungal threats. This device, along with her own models for potential disease outbreak, should aid vineyard management in developing treatment strategies for their grapes.
Join us tonight at 7PM PST to find out more! You can tune in to 88.7 KBVR or stream the show live online at http://kbvr.com/listen!
Cleistothecia on leaf: Fungal fruiting bodies (cleistothecia, approximately 130 µm diameter) of Erysiphe necator (causal agent of grape powdery mildew) under 20x magnification. Brown/black cleistothecia are mature enough for overwintering, whereas white and yellow fruiting structures are presently being formed.
Sieving: L.T. sieving cleistothecia being collected from leaves in cement mixer-ice water bath.
All photos courtesy of Lindsey Thiessen
