Rice Farming

Rice disease can cut straight into a farmer’s bottom line by slashing yields and reducing quality for the end-user. But farmers also need to keep in mind that disease can prove costly during milling, says Dr. Terry Siebenmorgen, professor of food science at the University of Arkansas in Fayetteville.

“The penalty for broken kernels used to be as much as 7 cents per percentage point per 100 pounds of rice,” he says. “If you go down from 60 to 55, for example, that would cost you 35 cents per hundredweight.”

In a tight economy, even small losses can add up quickly. Siebenmorgen was part of a team that documented the impact of blast and sheath blight on milling properties.

“I would say farmers better understand the correlation between blast incidence and overall yield,” he says.

“They also know how it can affect quality.”

More blast = more kernel breakage
Blast infection creates drier and thinner kernels; higher incidences of unfilled, fissured and chalky kernels; lower rough rice bulk density; and lower head rice yields. As a result, kernels are less able to withstand the rigors of the milling process.

“Blast affects the maturing of the kernel,” Siebenmorgen says. “The kernel’s normal pathways are disrupted, so you wind up with a thinner, weaker kernel. When it goes through post-harvest processing, it can’t withstand the pressure and breaks. Then it goes into the broken stream.”

The bottom line is that each 10 percent of blast incidence reduces yield by 6 percent and increases chalky kernels by 5 percent, which lowers rice quality by one or two classes.

Sheath blight effects are less severe
The impact of sheath blight on milling quality is less severe and more difficult to quantify, Siebenmorgen says.

Sheath blight infection from panicle initiation to flowering results in yield loss by reducing both grain weight and the number of filled grains. Sheath blight also interferes with grain filling and can reduce rough rice yield by 39 percent.

That loss can increase to 50 percent in terms of milled whole grain rice, because grains can be weakened and subsequently break during milling. A possible 46 percent yield loss in milled rice has been estimated if sheath blight lesions reach 90 percent of plant height.

Harvesting from diseased and disease-free portions of the same field results in a harvest lot with great variability in individual kernel thicknesses, which could affect drying and milling quality.

Keep milling in mind
Farmers should keep milling in mind when developing a fungicide program, says Dr. Ronnie Helms, a farmer and consultant in Stuttgart, Ark. That’s why he likes new Stratego fungicide from Bayer CropScience.

Stratego combines trifloxystrobin, a storbilurin fungicide, with propiconazole, the active ingredient in Tilt.

“By controlling secondary diseases, such as kernel smut and false smut, Stratego appears to enhance the milling quality of the rice,” he says.

Milling problems alone may not be enough to justify a fungicide application, but they can compound the losses already associated with yield and quality reductions.

For questions or comments, contact Rice Farming editor Vicky Boyd at (209) 571-0414 or vlboyd@att.net.

Avoid the milling penalty box Keep grain quality, end-user in mind when drafting fungicide plan
By Alan Goforth
Rice disease can cut straight into a farmer’s bottom line by slashing yields and reducing quality for the end-user. But farmers also need to keep in mind that disease can prove costly during milling, says Dr. Terry Siebenmorgen, professor of food science at the University of Arkansas in Fayetteville. “The penalty for broken kernels used to be as much as 7 cents per percentage point per 100 pounds of rice,” he says. “If you go down from 60 to 55, for example, that would cost you 35 cents per hundredweight.” In a tight economy, even small losses can add up quickly. Siebenmorgen was part of a team that documented the impact of blast and sheath blight on milling properties. “I would say farmers better understand the correlation between blast incidence and overall yield,” he says. “They also know how it can affect quality.” More blast = more kernel breakage Blast infection creates drier and thinner kernels; higher incidences of unfilled, fissured and chalky kernels; lower rough rice bulk density; and lower head rice yields. As a result, kernels are less able to withstand the rigors of the milling process. “Blast affects the maturing of the kernel,” Siebenmorgen says. “The kernel’s normal pathways are disrupted, so you wind up with a thinner, weaker kernel. When it goes through post-harvest processing, it can’t withstand the pressure and breaks. Then it goes into the broken stream.” The bottom line is that each 10 percent of blast incidence reduces yield by 6 percent and increases chalky kernels by 5 percent, which lowers rice quality by one or two classes. Sheath blight effects are less severe The impact of sheath blight on milling quality is less severe and more difficult to quantify, Siebenmorgen says. Sheath blight infection from panicle initiation to flowering results in yield loss by reducing both grain weight and the number of filled grains. Sheath blight also interferes with grain filling and can reduce rough rice yield by 39 percent. That loss can increase to 50 percent in terms of milled whole grain rice, because grains can be weakened and subsequently break during milling. A possible 46 percent yield loss in milled rice has been estimated if sheath blight lesions reach 90 percent of plant height. Harvesting from diseased and disease-free portions of the same field results in a harvest lot with great variability in individual kernel thicknesses, which could affect drying and milling quality. Keep milling in mind Farmers should keep milling in mind when developing a fungicide program, says Dr. Ronnie Helms, a farmer and consultant in Stuttgart, Ark. That’s why he likes new Stratego fungicide from Bayer CropScience. Stratego combines trifloxystrobin, a storbilurin fungicide, with propiconazole, the active ingredient in Tilt. “By controlling secondary diseases, such as kernel smut and false smut, Stratego appears to enhance the milling quality of the rice,” he says. Milling problems alone may not be enough to justify a fungicide application, but they can compound the losses already associated with yield and quality reductions. For questions or comments, contact Rice Farming editor Vicky Boyd at (209) 571-0414 or vlboyd@att.net.
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