Tag Archives: plant pathology

The Grape Depression: Powdery Mildew in Willamette Valley Vineyards

Brent at the Foliar Pathology Lab research vineyard where the small plot field trials in his project were conducted.

Viticulture is the science, production, and study of grapes, and when growing grapes for wine both quantity and quality matter. One challenge facing farmers in the Willamette Valley is a plant pathogen: grape powdery mildew. This pathogen can live in a field year-round and emerges to infect grape leaves, flowers and fruits annually. Grape plants infected with powdery mildew suffer low berry yields and mildew may affect the taste of wine. In the Willamette Valley, where vineyards abundant, grape powdery mildew is a big problem. Brent Warneke, a Master’s student in the department of Botany and Plant Pathology, is studying the effect of fungicide application timing on the reduction in severity of powdery mildew on grapes, and he is our guest on Inspiration Dissemination this week.

Moldy Grapes

A grape bunch severely infected with powdery mildew. Note the berry cracking, powdery appearance, and poor color accumulation.

Brent works at the USDA Horticultural Crops Research Lab with Walt Mahaffee, and his research tests the effect of fungicide application timing on grape powdery mildew control. Timing fungicide applications is especially crucial during the one to three-week window of grapevine flowering. Optimal fungicide application timing can slow the mildew epidemic allowing grape berries to mature and become less susceptible to powdery mildew. Across the Willamette Valley, fungicide application to grapes is a well-known prevention solution for powdery mildew, but less is known about the best fungicide to use and when to spray plants during berry development. The findings of his research are now being validated at a larger scale in commercial vineyards. In the lab, Brent is also studying the mobility of fungicide “through the grapevine,” from tissue to tissue through the air and xylem, and Brent is helping with a project to identify strains of mildew resistant to commonly used fungicides.


The Grape State of Colorado 

Brent with a harvest of varnish conk (Ganoderma oregonense), Lobster mushroom (Hypomyces lactifluorum).

Brent hails from Colorado where he spent his early years outside gardening, snowboarding, and hiking. During undergrad at Colorado State University (CSU), Brent majored in Horticulture and held research positions at the Center for Agricultural Resources Research and the Bioenergy Lab. Among his many projects during undergrad, Brent completed a senior thesis project, under the direction of Dr. Courtney Jahn, developing a LAMP-PCR to diagnose Canada thistle rust on infected plants that were not displaying symptoms.

Wine Not?

While at CSU, Brent also began studying viticulture. He liked the challenge and complexity of growing grapes for wine. Brent chose to pursue graduate school at Oregon State because his current program blends plant pathology with viticulture. He’s happy with his decision because Oregon is similar to Colorado for outdoor recreation, not to mention its world class Pinot Noir!

Hear more from Brent this Sunday September, 10 at 7PM on KBVR Corvallis, 88.7FM! Not a local listener? Not sweat! Stream the show live.

Brent on top of South Sister (10,363 ft). Middle and north sister can be seen in the immediate background. In the far background the small peak to the left without snow is Mount Washington , then Mount Jefferson behind north sister and Mount Hood in the background to the right of North Sister.

Ways and Means: Attitudes Toward Methods of Restoring American Chestnut Trees

“The Christmas Song” or “Chestnuts Roasting on an Open Fire” by Bob Wells and Mel Tormé is an iconic song in American culture, but most Americans will never experience a chestnut roast (at least not with American chestnuts).

A mighty blight

The American chestnut was a widespread North American native tree that covered nearly 200,000 miles of Appalachian forest. In 1904, the American chestnut trees in the Bronx Zoo were dying from a then unknown disease, Chestnut Blight. In the next forty years, Chestnut Blight spread across the estimated 4 billion American chestnut trees. Now American Chestnut trees are seen only as giant stumps, juveniles never reaching maturity, and rarely, adult fruit-bearing trees.

Since the decline of the American chestnut, Appalachian forests have changed. Chestnuts have been replaced by oaks, and it is likely that many organisms that relied on the chestnut trees for food or shelter have had to adapt to new conditions or have been displaced. The loss of the chestnut also led to the loss of financial income for many Appalachian people. In addition to chestnuts as a food source, the American chestnut provided decay resistant timber and tannins for tanning hide. The American chestnut and its decline is remembered through oral and written history. Members of older generations from Appalachia tell stories of enormous trees and later forests of white wooden chestnut skeletons.

Restoring the chestnut

Josh skiing in the mountains of Big Sky, Montana.

The restoration of the chestnut is an active project that faces many challenges. First, few Americans have seen an American chestnut tree, and few are familiar with their decline via Chestnut Blight. Since the restoration of the American chestnut would require policy changes and action across 200,000 miles, spanning multiple state governments, it is necessary to assess the extent the public might disfavor or favor this restoration. Our guest this week,Josh Petit from Forest Ecosystems and Society, is seeking to understand the attitudes of Americans toward the chestnut restoration. In particular, Josh is surveying a sample of the US population to compare attitudes toward a controversial method of chestnut restoration,  the use of genetic engineering.

Ways and Means

You may be familiar with genetic engineering to modify the genome of an organism to achieve a specific goal. Many of the crops we eat have in some way been modified to aid harvest, growth, and/or resistance to pests and disease. The methods for restoring the American chestnut are:

  • Selective breeding with related, blight-resistant Asian chestnuts
  • Modifying the genome of American chestnuts with Asian or other related chestnut genes (cisgenics)
  • Modifying the genome of American chestnuts with foreign genes or genes from wheat (transgenics)

Josh conducting research during a study abroad program in tropical North Queensland, Australia.

It is important to assess the attitudes of the public to transgenics because the introduction of  genes from wheat has been the most successful method at enhancing resistance toward chestnut blight. Recently, negative media has led to the misunderstanding that genetically modified organisms (GMOs) have adverse effects on consumers (humans) and ecosystems. However, these claims are not based in sound science and have been refuted. Although GMOs are being supported as alternatives to crop and forest species extinction, ultimately chestnut restoration relies on majority vote in favor or against a specific strategy. Thus, assessing attitudes toward restoration methods is tantamount to restoration efforts.

The Guy for the Job

A native of Ohio, Josh Petit attended Xavier University and majored in Political Science. He credits a Semester at Sea for broadening his world view and exposing him to different cultures. He learned that culture is important in all aspects of daily life. In retrospect, perhaps it is no surprise that he is currently studying an iconic tree and how culture has driven attitudes toward its restoration.

Josh participating in a Fijian traditional village celebration and homestay–taking turns playing guitar.

Josh became interested in ecology, biology, and the interface of the two with humans while working for Q4 International Marketing an ecotourism company in Panama. This lead him to pursue a Master’s in Natural Resources with a marine ecology focus from Virginia Tech. However, his most recent work withOregon Parks and Recreation Department lead him to pursue a PhD at Oregon State University. With the State Parks, Josh conducted surveys in Oregon Parks and sought to connect behavior, impacts, and social science to ecology and recreation. Now at Oregon State University, Josh is working with Mark Needham andGlenn Howe to understand the drivers of attitudes toward using biotechnologies for restoring American chestnut trees.

Hear more about Josh’s research and his journey to now this week on Inspiration Dissemination. Tune in to KBVR Corvallis 88.7FM on Sunday July, 30 at 7 pm, or live stream the show.