Skip to main content Skip to navigation

Resistance Management, Water

WSU Scientist Advocates Fungicide Stewardship

Chang-Lin Xiao. Photo by Brian Charles Clark
Chang-Lin Xiao. Photo by Brian Charles Clark

It’s every doctor’s worst nightmare. Whether a healthcare practitioner for people, animals or plants, discovering that a disease (pathogen) has evolved resistance to your front-line defense is bad news. We’ve heard about it with a form of Staphylococcus that is resistant to multiple antibiotics, making it tough for doctors to treat. The same sort of process can happen with fungal infections in plants. That’s why WSU plant pathologist Chang-Lin Xiao is urging tree fruit industry professionals to rotate their use of key fungicides.

“In order to maintain our market share for Washington-grown tree fruits,” Xiao said, “we must be able to control pathogens. That means being on the alert for the development of resistance in pathogens.”

Xiao pointed out that fungicide manufacturers naturally want their product to be used year after year – that’s how they make the most money. But there’s been a change in that attitude based on the advocacy of Xiao and others. For control of postharvest rots of tree fruits, manufacturers and other industry professionals now understand that in order to maintain a product’s efficacy it must be used in rotation with other products –- even if rotation means that another manufacturer’s fungicide gets a piece of the market. “We have effective tools, but must use them judiciously,” Xiao said.

But Xiao is not relying solely on a defensive posture to ensure the future efficacy of fungicides. He’s taking an aggressive stance toward detecting resistance in the fungi themselves. “We are using molecular biological techniques to look for resistance in pathogenic fungi,” he said. “We are monitoring both orchards and packing houses, looking for strains of resistant fungi. We study the biological and ecological characteristics of fungicide-resistant strains and use what we learn to make application recommendations to growers and packing houses.”

Xiao and his colleagues also host annual WSU Fruit School meetings. There, they pass on new information to industry professionals in a timely manner.  The results have been positive, with manufacturers now recommending rotating fungicides. “This is a progressive agricultural industry,” Xiao said. “The various parts of the industry” — growers, packers, and chemical manufacturers — “work together to make it both profitable and sustainable. It’s gratifying to work with such a forward-looking group of people to provide science-based solutions to the issues they face.”

by Brian Clark

For more information, please visit http://bit.ly/postharv.

Water, Water, Not Quite Everywhere

Wheel line irrigation system (courtesy USDA)
Wheel line irrigation system (courtesy USDA)

When I was a kid I was “born again,” a process that involved being fully and totally immersed in water. Much more recently I was on the home stretch of an 8-mile walk in the hot sun when the minister I was walking with kindly poured her drinking water on my hot little head.

Seldom does water feel so good as when splashed on an overheating noggin in the summertime. As soon as my hair was sopping wet, I felt born anew, able to complete the walk with at least a tiny smidgen of spring in my step. Just a cup or two of water, supplied at the crucial time and applied to best advantage, made all the difference in the world.

What would you imagine is the largest use of water in the U.S.? We all can guess it’s not drinking water itself, nor wetting the heads of aging geologists. Would it be what goes on everyday in kitchens for meal preparation? Or the weekly washing of laundry? Bathrooms and what we do in them? Perhaps commercial car washes use more water than your home?

Actually, irrigation makes up the most significant use of freshwater in the U.S. In a nutshell, some farmers use a lot of water to grow crops on semi-arid or marginal land.

Techniques range from flooding fields to using pressurized sprinklers to anoint crops with much needed artificial rain.

There are some significant drawbacks to irrigation. Freshwater is a precious resource, and using so much of it for farming can be criticized as profligate. Beyond that, irrigation can degrade soil, making it saltier over time as water evaporates repeatedly in hot and dry regions where irrigation is commonly practiced.

But there are two major ideas to keep in mind when it comes to irrigation. The first is that around the world irrigation truly helps us produce food for the seven billion mouths we now have to feed on the planet.

In various parts of the U.S. we irrigate to grow everything from vegetables to wheat and rice. Almost all states in the Union have some measure of irrigated agriculture within them. And, as most of us vaguely know but we don’t often articulate, American farmers feed us well and also produce enough for many millions of others around the world to whom our harvests are exported.

All those facts came to mind recently when I read of a University of Wisconsin study about irrigation on a global scale. The bottom line of the study was that global irrigation patterns increase farming output substantially. In fact, that increase is almost as great as all of U.S. farming output rolled into one sum –- and we grow a lot of food in this country, so that ain’t nothing to sneeze at.

Dr. E. Kirsten Peters, a native of the rural Northwest, was trained as a geologist at Princeton and Harvard.
Dr. E. Kirsten Peters, a native of the rural Northwest, was trained as a geologist at Princeton and Harvard.

Agricultural productivity and irrigation aren’t the same everywhere because a little bit of water in a dry field can increase yields much more than a lot of water in a wetter region. Interestingly, the Wisconsin researchers believe irrigation around the world is used close to maximum efficiency.

In some ways the efficiency of global irrigation is good news -– we humans are not being wasteful with respect to a very large chunk of our freshwater resources. But it also means that as the population continues to increase, we can’t feed more mouths just by upping our irrigation efficiency.

One reason scientists and engineers are studying matters like irrigation is that people have become interested in all forms of carbon uptake from the air. If you grow plants, they “mine” carbon dioxide out of the air to build their carbon-rich little selves. A tree locks up this carbon for years or even centuries to come. By comparison, a crop plant like wheat only temporarily stores carbon.

Freshwater is one resource that, like energy, goes into all sorts of our products and activities. It’s so much cheaper than gasoline, we normally don’t think of it as we go about our daily lives. But it’s a limited resource the use of which has significant environmental impact. What we want to do with it is something we could well afford to think about more clearly.

One thing is evident to me: I want us to always have enough water to pour over the heads of old ladies taking long walks on hot summer mornings.

by Dr. E. Kirsten Peters

If you aren’t already reading the Rock Doc in your local paper, ask for her — or check out Dr. Peter’s weekly column online at rockdoc.wsu.edu. Follow her on Twitter @RockDocWSU.