Next Generation Farming

Leaf Rust in Wheat Expanding in Kansas

Rust in wheat is spreading rapidly, but can be controlled cheaply and easily

After last year's assault of heat and drought, a cool and wet spring is hardly grounds for complaining. An outbreak of rust, though, is still on our radar.

Leaf rust and stripe rust have already been confirmed in central and southern Kansas, which lies directly in the path of storms that carry in fungal spores from Texas and Oklahoma.

Now, thanks to the cool and damp conditions we've experienced in the past few weeks, leaf rust is showing up in our fields here in Lane County in west-central Kansas. The fungal spores are right where you'd expect them – below the leafy canopy on the lower leaves where conditions are moist and cool.

Fortunately, the incidence of leaf rust on our farm is limited to only a few fields and has not spread to the upper leaves or the flag leaf where the plant takes in the most nutrients. We also have a fairly comfortable window to control a potential outbreak thanks to having spotted the rust spores early in development.

According to university guidelines, fungicide applications made between flag leaf emergence and flowering have the greatest disease control and biggest yield benefit. Our fields for the most part are currently in the early boot stage. The main flag leaf has emerged on most plants, but not all.

Cutting to the chase, what will it cost this year to control a rust outbreak in your wheat? It turns out there is a huge price disparity on fungicides. While there are a number of brands to choose from, K-State research shows some convincing evidence that the bargain basement generic fungicides that have a 21-day residual are just as effective for controlling rust as the high-dollar brand-named products.

Folicur, which in the past has been the cheapest fungicide on the market, has been quoted as high as $13/acre in our area this season. The prices on other fungicides are even higher.

But, if you're willing to shop outside of your local area, fungicide can be bought at extremely competitive rates. One chemical dealership across the state line in Colorado sells Tebu, which has the same active ingredient as Folicur called tebuconazole, at the extremely affordable price of $2.06/acre when applying at the recommended rate of 4 oz/acre.

Including K-State's projected application cost of $5.48/acre, that comes to only $7.54/acre to control the rust spreading throughout wheat country – assuming, of course, that you only spray once and you spray at precisely the right time. That all depends on if and when you're scouting your fields.

 

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