Update on Phylloxera in Colorado

Here is a press release from the Colorado Wine Industry Board on the discovered Phylloxera in Colorado’s vineyards…..

April 17, 2017 — Last November, The Colorado Wine Industry became aware of the presence of grape phylloxera (Daktulsphaira vitifoliae) in Colorado’s Grand Valley American Viticultural Area (AVA), which is home to three-quarters of the state’s grape acreage stretching between Palisade and Grand Junction. This insect, capable of damaging Colorado’s wine grape crop by feeding on roots of grape plants and disrupting water and nutrient flow, has been found in many other wine regions including California’s Napa Valley.  After several months of assessing the situation, Colorado State University and Colorado Department of Agriculture scientists have identified about eight isolated vineyard locations infested with grape phylloxera. Those growers are taking the necessary steps to restrict the further spread of the pest, to eradicate the affected vines and remain positive about this year’s wine production.

“The presence of phylloxera to Colorado is not a reason to panic,” explains Warren Winiarski, founder of Stag’s Leap Wine Cellars and owner of Arcadia Vineyards in the Napa Valley. “We in California have successfully dealt with phylloxera over a relatively short period of time, but I would expect the movement of the bug between Colorado vineyards would be a relatively slow process, like that experienced by Oregon and Washington according to Mark Chien (Oregon Wine Research Institute). The difference in these states seems to have been the cold winters. The cold winters that sometimes prove problematic to Colorado’s vines should, along with other factors, also help slow the spread of phylloxera.”

One impacted grower, John Behrs of Whitewater Hill Vineyards in Grand Junction, mentions he is following tried and proven techniques to manage their Phylloxera starting with a sampling survey and destroying infected vines. “We have and will continue to frequently sample for this pest to determine the extent of infection.  At this point it is localized to a small area,” explains Behrs.  “Initially, we will destroy all vines that test positive.   We have destroyed 300 vines thus far.   Currently, the infected area has been removed and Phylloxera is no longer detectable in our vineyards. We have over 20,000 vines, so the percentage of infection is small at this point, and impact on overall crop yield is negligible.”

More aggressive options are also available to help curtail the infestation. Behrs describes adding some sprays to slow the pest down, along with more cautious sanitation techniques to reduce spread.  Behrs states, “These techniques are proven to reduce the rate of infection by over 90%.”

“Over time, as the problem spreads (and it spreads slowly) we will have to gradually replace the infected vines with those grafted onto resistant stock, such as those used extensively in California and France,” acknowledges Behrs.  “Since the spread of phylloxera will likely be gradual, it will not impact the quantity or quality of the wines available to our Colorado wine fans.”

Colorado has approximately 150 grape growers tending nearly 1,000 acres of vineyards and more than 140 licensed commercial wineries.  These vintners produced 166,000 cases of wine during the 2016 fiscal year, which equaled more than $33 million in sales.

The latest evaluation of the phylloxera outbreak is a relief for the burgeoning Colorado wine industry which has seen a 40 percent growth over the last five years and hopes to continue on this trajectory. Market share by volume hit an all-time high last year, with nearly one dollar of every twenty dollars spent on wine in Colorado going to the purchase of a wine made here in the state – a notable sign that people are beginning to support the local wine industry with their purchasing decisions.

“While this makes things more complicated for local grape growers, it is unlikely to result in any long-term effects or a reduction in the state’s overall production,” remarked Doug Caskey, executive director of the Colorado Wine Industry Development Board. “The Colorado wine industry continues to expand its market share in the state, thanks to the tremendous quality of the wines, improved growing conditions and the efforts of so many who are successfully shining a light on this burgeoning industry.”

Today, Colorado’s 140 wineries are recognized nationally for their high quality. A recent story focusing on Colorado’s wineries was featured on renowned wine critic Robert Parker’s Wine Advocate website. Author R.H. Drexel found Colorado’s wines “capture the magic of Colorado’s high-elevation terroir.” Colorado wines are a reflection of the state’s unique and sometimes harrowing growing conditions, producing world-class grapes grown on nearly 1,000 acres of vineyards at the highest elevations in the country. The industry continues to expand and adapt to meet the demands of consumers as well as the unique high-elevation environment. Many of the state’s wineries have been able to increase production over the last two years thanks to extremely productive growing seasons in succession.

“Phylloxera has affected so many regions around the world, yet every one of them has bounced back from this little pest,” said Sally Mohr, Master Sommelier and Boulder resident. “It will take time and, yes dollars spent, to replace vines that are affected and also to replant vineyards with phylloxera-resistant rootstock.”


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