Among the whole host of calamities that have lined up to wreak havoc on the area wheat crop, diseases are among the last, but they may not be the least.

Speaking at the Southeast Agriculture Research Center’s annual wheat field day last week, Kansas State University Plant Pathologist Doug Jardine noted that many of the usual suspects have been at work.

Statewide, he said, leaf rust and powdery mildew have been the primary culprits.

Powdery mildew has been a particularly serious problem because Jagger is highly susceptible to the disease, Jardine explained, and Jagger genetics are in over half of the wheat planted in the state.

“Throw in the right conditions for the disease and it’s not really a surprise that powdery mildew is potentially a big problem,” he said, adding that there are several hard red winter wheat varieties available which do boast respectable resistance to the disease.

Leaf rust, typically the biggest overall yield robber, is a particular problem for varieties such as Jagger which are highly susceptible.

Stripe rust, on the other hand, hasn’t been a big problem this year, the plant pathologist said, but he cautioned growers to keep it in mind when selecting varieties.

There was good news and bad news regarding barley yellow dwarf disease, Jardine noted. The bad news is that there has been a good deal of barley yellow dwarf infection but the good news is that it came in the spring rather than in the fall which normally results in more serious yield damage.

The freeze did one good thing, Jardine said, in that it killed off a lot of the insects that carry disease.

Regarding the use of fungicides, he said there are a half-dozen or so treatments that are fairly effective on most foliar diseases. Normally, growers needed 40-45 bushel per acre yield potential to justify application which costs roughly $12-$15 per acre and typically delivers a yield bump of 10-30 percent.

Higher wheat prices, however, make fungicide use much more economical.

Jardine also said that a half-rate, early-season application is not generally recommended. It may have some benefit in the case of powdery mildew, he said, but it won’t help if there is leaf rust on flag leaf because it occurs too late in the season.

If a producer applies a reduced rate early and then is faced with a full application because of leaf rust later on, the two applications would be difficult to justify on an economic basis.

Jardine urged producers to look at disease resistance in addition to maturity and yield potential when evaluating varieties.

Explaining that there is no good resistance for barley yellow dwarf, he suggested that growers look for a good resistance package for diseases such as powdery mildew, leaf rust, tan spot, septoria and stripe rust.

K-State, Jardine pointed out, has disease resistance ratings for virtually all of the wheat varieties planted in the state.

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