Tag Archives: K-State

MANHATTAN, Kan. – A Kansas State University row crop specialist says he’s happy – even if surprised – by the low incidence of disease he’s finding in the state’s corn fields so far this summer.

But he’s urging growers to continue scouting their fields for diseases that have been commonly found in Kansas in past years.

“I have been surprised by the low levels of gray leaf spot in most fields,” said Doug Jardine, who has traveled several areas of Kansas over the past few weeks looking at corn and soybean fields.

“In those areas where I was able to find gray leaf spot, it was on the very lowest leaves, even in some fields that I know have had a problem with a history of this disease.”

Gray leaf spot is a fungus that causes an estimated loss of 9 million bushels of corn per year in Kansas. It was first found in the state in 1989, and is considered the most serious foliar disease of corn in Kansas and the north central United States.

For that reason, indications that it might not be as prevalent so far this summer is no reason for growers to become complacent.

“It’s present in the state, so we need to be scouting,” Jardine said. “But at this point, I was not personally in any fields that I think are going to need a fungicide this year. And given the commodity prices this year, if we can save $15 to $25, that’s probably a good thing.”

He added that the lower incidence of the disease in Kansas could be due to growers’ tendency in recent years to plant hybrids containing tolerance to gray leaf spot, “because that’s what we’ve preached as the primary management practice for years.”

Jardine said that gray leaf spot is sometimes confused with another disease that shows up routinely in Kansas – bacterial leaf streak, a bacteria that is more common in corn fields managed under continuous no-till and center pivot irrigation.

He noted that bacterial leaf streak is mostly found in the western one-third of Kansas, but has been found recently in the southeast (Labette County), north central (Clay County) and south central (Butler County) parts of the state.

“To an untrained eye, this disease can look very similar to gray leaf spot,” Jardine said. “We know over the last 3-4 years that people thought they had gray leaf spot, went out and sprayed and saw no response to the fungicide application – that’s because fungicides don’t work on bacteria.”

Differences between the two diseases are often seen in the lesions that appear on the leaves of the corn plant.

“With gray leaf spot, the lesions are defined by the vein, so they have very sharp borders on them; they don’t cross the vein,” Jardine said. “With bacterial leaf streak, they don’t respect that vein, so they can have a wavy edge that crosses the border and comes back. They tend to be very long and linear.”

He noted that another test is to hold up an infected leaf so that it is back-lit by the sun. If the light passes through readily (translucent), the disease is likely to be bacterial leaf streak. But if light doesn’t pass through the lesions (opaque) and appears dark brown, the disease is likely to be gray leaf spot.

In either case, Jardine suggests that growers submit samples of suspect leaves through their local extension office, or send directly to the plant disease diagnostic lab at Kansas State University.

In addition, Jardine said corn growers should be on the lookout for signs of the root lesion nematode, which were “very severe” in northeast Kansas (Doniphan and Brown counties) a year ago.

Producers who suspect an infestation of root lesion nematodes should dig up whole plants 30-40 days past emergence, shake off the excess soil from roots, and send the sample into the plant disease diagnostic lab.

Jardine said one sample received at K-State a year ago had a count of 100,000 nematodes per gram of root weight. That’s a huge number considering that yield losses in corn are common with infestations of 5,000 to 10,000 nematodes per gram of root weight.

“You’re looking for stunted areas in the fields, especially if they’re starting to become a little chlorotic (yellowish),” Jardine said.

Specific to soybeans, Jardine said he’s keeping his eye out for the presence of frogeye leaf spot, which could take hold in some fields this year because of the wet June weather in Kansas.

More information on crop diseases in Kansas is available from K-State’s Department of Plant Pathology, and the weekly e-Update published by the Department of Agronomy.

Potato lovers are sure to find this research about spuds appealing.

Chetan Sharma is completing his doctorate in human nutrition at Kansas State University’s Olathe campus under the guidance of Martin Talavera, assistant professor of sensory analysis and consumer behavior. For his dissertation, Sharma is conducting a comprehensive, multiyear project that looks at the sensory aspects of potatoes — one of the world’s largest food crops. He is focusing specifically on the drivers behind what people like about potatoes.

“If someone says that they ‘like’ something, such as coffee or chocolate, we understand it to mean that they found that food enjoyable,” Sharma said. “But for companies that produce foods and products, a consumer saying they ‘like’ something is a vague descriptive term that doesn’t provide insight about what that means and why. This creates a knowledge gap when it comes to making products people want.”

Sharma is working to decode vague concepts, such as “like” and taste, into a common language that helps sensory researchers, potato breeders, restaurants and other food producers better align potato and potato products with consumer expectations and desires.


For the first phase of the project, Sharma worked with universities in Colorado and Oregon to collect 55 potato varieties among the more than 4,000 grown worldwide. Sharma also worked with the Center for Sensory Analysis and Consumer Behavior at Kansas State University’s Manhattan campus to develop a technical language comprised of sensory descriptors. The language, called a lexicon, helps breakdown, standardize and streamline terminology involving the taste, smell, visual appearance, texture and mouthfeel of several potato varieties. Mustardy, cauliflower, beany, earthy, cardboard and metallic are some of the flavor nodes included in the potato lexicon.

Food producers and restaurants can use the lexicon as a reference when selecting potatoes for a food, Sharma said. For example, if mashed potatoes were being made, a potato variety that has a metallic aftertaste can be avoided in favor of a variety that has a smooth finish.

In addition to serving as a guide, the lexicon also establishes a historical record documenting the sensory profile of potatoes in 2019, which may be beneficial to potato breeders, Sharma said. Flavors tend to change as foods are bred throughout the ages and many modern foods have been bred to have a sweeter taste than their counterparts centuries ago.

For the second phase, the 55 varieties were narrowed to 12 based on diversity and dynamic characteristics such as bold flavor, texture and color.

Sharma conducted consumer testing with 100 consumers to evaluate each of the 12 potato varieties on liking, taste, texture, aroma and visual appearance.

Two questionnaire types were used to collect information from participants. One questionnaire asked open-ended questions, letting participants create their own terminology to describe the characteristics of each potato sample. The second type, which was given to a new test audience, presented participants with a predetermined list of descriptor terms and asked them to check all that applied to a sample.

The goal was to benchmark the lexicon, determine which questionnaire provided researchers with the most information and also test consumer perceptions about each of the 12 potato varieties. Additionally, questions looked at whether different consumer segments detected texture, aroma, bitterness and other characteristics differently.

Some of Sharma’s findings include that people prefer the cooked taste versus roasted or raw and a more smooth than dry texture. He also found that color deeply affects perception and opinion.

“People do not like color,” said Sharma, who included varieties of purple and canary yellow potatoes in tests. “Even though these colored potatoes had characteristics that were similar to the more familiar varieties like russet or white, they were disliked because of their color. People reported that they enjoyed them if they closed their eyes, but otherwise they said these colored varieties did not look like potatoes.”

He said this presents companies with the opportunity to advertise the health benefits of these colorful potatoes in an effort to change consumer perception.

Sharma is currently conducting the third phase of the project, which sheds light on what qualities people think about when buying potatoes and how that affects their purchase. He is looking at multiple factors that may influence decision-making, including potato variety, where the potato is grown and whether the potato is organic.

Sharma will present his research this summer for his doctoral dissertation.