Next Generation Farming

Stripe Rust: A "Perfect Storm" in 2010

Wheat crop could suffer 15 to 20 bu. per acre yield losses.

Not long ago the crop in our area of Kansas looked like a bin-buster. Now, after hearing some of the disaster stories out there and seeing some neighboring fields up close, it's obvious the tables have turned and stripe rust has hit this crop with a vengeance.

The sheer severity of stripe rust – a rapidly spreading fungus that stunts plant growth – took everyone by surprise. Even varieties that were resistant to stripe rust last year have turned susceptible. All this was on exhibition last week when our local county extension agent organized the annual Lane County Wheat Tour on my family's farm with 26 wheat varieties in the plots. Only five varieties showed any resistance to stripe this year.

This is devastating news. Most of the wheat varieties out there are rendered virtually useless when planted alone. Wheat breeders are even throwing out 40-60% of their breeding stock due to stripe rust's merciless return to wheat fields across the Southern Plains.

Hard Hit Yields According to state plant pathologist Eric DeWolf, who was in attendance, fields that did not have a timely application of fungicide this year will see yields drop like a rock. Yields will fall to 15-20 bushels/acre and test weights will suffer, which will cost even more in dockage at the elevator.


What's even worse is that some farmers who haven't checked their fields lately still have no clue about the disaster they are going to see at harvest.

The source of the problem goes back to Jagger – a popular wheat that is the parent of many of today's varieties. When Jagger was released in the mid 90s, it was a blockbuster hit among wheat farmers from Texas to Nebraska. It had strong resistance to stripe rust, leaf rust and wheat streak mosaic, and worked well for grazing. Everyone planted it – which is the start of the problem.

With everyone planting Jagger all across the Southern and Central Plains, the door was left wide open for Mother Nature to adapt. It was only a matter of time for pests to evolve around Jagger's superior genetics. Now, anything that has Jagger parentage is virtually useless since that genetic package no longer carries resistance.

As Northwest Kansas regional crops and soils specialist Brian Olson describes it, everything finally came to a head this spring when storms brought drenching rains – and fungal spores – all the way from Texas, where stripe rust overwinters.

With such widespread and intense dispersal of the fungus – combined with the weakening resistance in varieties carrying Jagger's genetics – the camel's back finally broke. Fields all over the Southern Plains are now swimming in rust.

In some cases, the rust is so bad the fields turn completely yellow as the leaves die – starving the head of badly needed nutrients. And with harvest just around the corner, it's too late in most fields for a fungicide application to have any effect.

Lessons for the future? Eric DeWolf says that from now on, farmers cannot rely on one single genetic package anymore. Rather, we must plant a number of varieties with a diversity of resistance. And of course, check your fields. You don't want to be one of the farmers who finds out too late that he doesn't have a crop.

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