Rice Farming

A group of Texas A&M researchers believe they’re on the right path to make sweeping changes in the way you sample for rice stink bugs. After two years’ worth of replicated field trials, they’re fairly confident that using a simple 3-foot-long PVC pipe produces similar results as using a cumbersome sweep net. And it’s much faster.

“You look funny, but it’s really easy to do, and it’s much better than a sweep net. And I’ve done a lot of sweeping with the net,” says Luis Espino, a graduate student in integrated pest management who’s conducting the trials.

The group, comprising Espino and his advisers, Drs. Mo Way and Jim Olson, will take the data to the field this year to validate their findings. One thing Espino wants to solidify is whether you’ll only need to make two or three sweeps with the stick before moving to the next sampling site within the field.

They also hope to develop an easy-to-read chart featuring a sequential sampling scheme.

Espino theorizes if you get extremely low or high average stink bug counts after making three sweeps with the stick, then you may be able to stop sampling in that field that day. But if your average stink bug counts fall in the middle, then you may need to make a few more sweeps.

In addition, Espino plans to conduct caged trials in a greenhouse this summer to ensure that current rice stink bug thresholds are still valid, considering newer, more expensive, varieties and hybrids have come on the market.

Not only will he be looking at the effects of different stink bug densities, but he plans to examine how their feeding at different rice growth stages may affect rice yields and grain quality.

Current rice stink bug thresholds
Currently, Texas A&M Extension specialists recommend starting sampling for rice stink bugs when 50 percent to 75 percent of the rice panicles have emerged. To sample, they recommend making 10 sweeps in each of 10 different random locations within a field.

If you average five or more adults per 10 sweeps during the first two weeks, they recommend treating. After the first two weeks, the treatment threshold increases to 10 adults per 10 sweeps.

Because these are just guidelines, Way says some consultants and growers will treat when the threshold reaches just three adults early in the season.

Based on the findings this season, Way says they hope to have recommendations on new sampling techniques growers can use for the 2006 season. The possible new techniques will be in addition to any revisions to sweep net treatment thresholds.

A kindler, gentler sampling method
Espino began his quest for an easier way to monitor rice stink bug populations two years ago.
“I knew I wanted Luis to work on stink bugs, and I knew one of the big reasons why farmers don’t use sweep nets is because they’re so difficult, so we went from there,” Way says.

Working with cooperating growers, Espino divided several fields into grids and sampled each grid several times throughout the season.

Not only did he choose fields with low stink bug populations, but he also sought fields with a history of high stink bug infestations.

Among the tools he explored was the T-tool—two pieces of PVC pipe joined to form a T—that many consultants and some growers use to scout for sheath blight.

He used it to push the panicles aside and count the number of rice stink bugs he saw. But he found you had to know how fast you walked.

“The problem is you have to know your pace, and that might be a problem,” Espino says. “You have to count for 15 seconds or 20 seconds, and you try to make it the same distance every time you do it.”

PVC pipe fills the bill
He also looked at a 3-foot-long piece of about a half-inch diameter PVC pipe he has dubbed the sweep stick.

The name actually is a misnomer. Espino doesn’t actually use the stick to sweep the field. Instead, he takes a step and uses the PVC pipe to gently part the rice panicles.

This prompts some stink bugs that may be deep in the plant to move upward.

Then he counts the stink bugs he sees on the plant close to the last 15 inches of the stick.

He then takes another step, parts the plants and counts again. He may take one more step, repeating the same procedure. He then moves to another part of the field and repeats it.

“The stick gives me a reference when I go into the field,” Espino says. “I count how many stink bugs I can see—some will be flying and some will stay on the panicle. I try to go as fast as I can.

“I’ve done up to 10 sweeps with the stick, but it takes quite a long time if I do 10. But it may be faster if we just do two or three.”

In each case, he timed how long it took to sample with the method and compared the times and bug counts to the traditional sweep net.

Although the data is still preliminary, Espino says the sweep stick looks like a promising replacement for the sweep net. So far, the rice stink bug counts he’s obtained with the stick correlate fairly well to those from the sweep net.

A sweeping change New stink bug sampling method may save time, is easier than nets
By Vicky Boyd Editor
A group of Texas A&M researchers believe they’re on the right path to make sweeping changes in the way you sample for rice stink bugs. After two years’ worth of replicated field trials, they’re fairly confident that using a simple 3-foot-long PVC pipe produces similar results as using a cumbersome sweep net. And it’s much faster. “You look funny, but it’s really easy to do, and it’s much better than a sweep net. And I’ve done a lot of sweeping with the net,” says Luis Espino, a graduate student in integrated pest management who’s conducting the trials. The group, comprising Espino and his advisers, Drs. Mo Way and Jim Olson, will take the data to the field this year to validate their findings. One thing Espino wants to solidify is whether you’ll only need to make two or three sweeps with the stick before moving to the next sampling site within the field. They also hope to develop an easy-to-read chart featuring a sequential sampling scheme. Espino theorizes if you get extremely low or high average stink bug counts after making three sweeps with the stick, then you may be able to stop sampling in that field that day. But if your average stink bug counts fall in the middle, then you may need to make a few more sweeps. In addition, Espino plans to conduct caged trials in a greenhouse this summer to ensure that current rice stink bug thresholds are still valid, considering newer, more expensive, varieties and hybrids have come on the market. Not only will he be looking at the effects of different stink bug densities, but he plans to examine how their feeding at different rice growth stages may affect rice yields and grain quality. Current rice stink bug thresholds Currently, Texas A&M Extension specialists recommend starting sampling for rice stink bugs when 50 percent to 75 percent of the rice panicles have emerged. To sample, they recommend making 10 sweeps in each of 10 different random locations within a field. If you average five or more adults per 10 sweeps during the first two weeks, they recommend treating. After the first two weeks, the treatment threshold increases to 10 adults per 10 sweeps. Because these are just guidelines, Way says some consultants and growers will treat when the threshold reaches just three adults early in the season. Based on the findings this season, Way says they hope to have recommendations on new sampling techniques growers can use for the 2006 season. The possible new techniques will be in addition to any revisions to sweep net treatment thresholds. A kindler, gentler sampling method Espino began his quest for an easier way to monitor rice stink bug populations two years ago. “I knew I wanted Luis to work on stink bugs, and I knew one of the big reasons why farmers don’t use sweep nets is because they’re so difficult, so we went from there,” Way says. Working with cooperating growers, Espino divided several fields into grids and sampled each grid several times throughout the season. Not only did he choose fields with low stink bug populations, but he also sought fields with a history of high stink bug infestations. Among the tools he explored was the T-tool—two pieces of PVC pipe joined to form a T—that many consultants and some growers use to scout for sheath blight. He used it to push the panicles aside and count the number of rice stink bugs he saw. But he found you had to know how fast you walked. “The problem is you have to know your pace, and that might be a problem,” Espino says. “You have to count for 15 seconds or 20 seconds, and you try to make it the same distance every time you do it.” PVC pipe fills the bill He also looked at a 3-foot-long piece of about a half-inch diameter PVC pipe he has dubbed the sweep stick. The name actually is a misnomer. Espino doesn’t actually use the stick to sweep the field. Instead, he takes a step and uses the PVC pipe to gently part the rice panicles. This prompts some stink bugs that may be deep in the plant to move upward. Then he counts the stink bugs he sees on the plant close to the last 15 inches of the stick. He then takes another step, parts the plants and counts again. He may take one more step, repeating the same procedure. He then moves to another part of the field and repeats it. “The stick gives me a reference when I go into the field,” Espino says. “I count how many stink bugs I can see—some will be flying and some will stay on the panicle. I try to go as fast as I can. “I’ve done up to 10 sweeps with the stick, but it takes quite a long time if I do 10. But it may be faster if we just do two or three.” In each case, he timed how long it took to sample with the method and compared the times and bug counts to the traditional sweep net. Although the data is still preliminary, Espino says the sweep stick looks like a promising replacement for the sweep net. So far, the rice stink bug counts he’s obtained with the stick correlate fairly well to those from the sweep net.
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