Rice Farming

Rice stink bug is an increasing concern across the Southern rice-producing regions, delivering a one-two punch on both yield and quality in heavy infestation years.

“As far as insects are concerned, rice stink bug is the No. 1 pest in rice in Arkansas,” says Don Johnson, an entomologist with the University of Arkansas Extension Service in Little Rock. “The last several years, stink bug has been our major pest because it can have such an impact on the yield and quality of the crop.”

Rice stink bug is also quickly becoming the leading insect pest of Texas rice producers and is second in Louisiana, only to the rice water weevil.

In 2001, the heaviest rice stink bug year in memory, Johnson says the insect caused an estimated $25 million to $30 million in crop losses in Arkansas, with virtually every acre of rice in the state requiring treatment. Typically, however, about one-third to one-half of the state’s rice is treated for stink bug, at a cost ranging from $5 to $8 per acre. One or two applications are often enough to control an average outbreak.

Tiny bug, big losses
Unmanaged, though, stink bug can cause an estimated 10-percent yield loss in a given season, not to mention losses due to impacts on quality. Stink bug can damage rice throughout heading, and growers must be diligent prior to heading and throughout the period the crop is vulnerable, says Boris Castro, a rice Extension entomologist with the Louisiana State University’s Department of Entomology in Baton Rouge.

During the first two weeks after heading, rice stink bug will directly reduce yield by feeding on the panicle of flowering rice heads, killing embryos and destroying kernels. From two weeks after heading until the head starts to dry down, stink bug continues to threaten the crop’s quality by leaving an opening for pathogens that can lead to rice peckiness or staining.

Control grassy vegetation
Castro says an integrated rice stink bug management program actually begins by controlling grassy weeds in rice fields and along roads, levees and borders. That’s where stink bug populations overwinter and build before moving into the preferred flowering rice as grasses begin to dry down.

“The best way to keep these populations low is to control grassy weeds throughout the season,” he says. “If growers allow grasses to mature, they can make the whole thing worse by driving them into rice later. It’s better to do a top job controlling those grasses and then start monitoring the field early when you have 50 to 75 percent heading.

A fully integrated program
Morgan Smith, who grows and manages more than 3,000 acres of rice in northern Louisiana’s Richland and Ouachita parishes, says rice stink bug management is an integrated program of monitoring, treatment and managing grassy weeds in the field and along the perimeter and even in other crops such as corn and soybean, which can provide an overwintering habitat for the pest.

“The first stage of stink bug management is to have good herbicide management in your crop so that you don’t have host plants for the bugs before the rice heads,” Smith says. “Take care of your barnyardgrass or your sprangletop and also manage your ditch banks.”

Smith often tankmixes an insecticide with herbicides when spraying grasses on perimeters and roads to kill overwintering insect populations and keep them from migrating into rice at heading.

Monitor to time treatments
As heading approaches, monitoring the rice field becomes the primary component in rice stink bug management to keep pest levels under control as they reach treatment thresholds. Treatment thresholds are based on sweep net counts, although current research is underway to determine if an economical monitoring trap is also feasible to improve early monitoring along the field periphery.

“Monitoring is very important because growers need to be aware of the presence of insects even before rice starts heading out,” Castro says.

Start sweeping rice fields at about 50 percent to 75 percent head emergence, taking 10 sweeps from up to 10 representative locations within the field.

Sweep net thresholds for the pest are much lower during the first two weeks of heading when yield damage is most likely.

Castro recommends treating during the first two weeks when sweep net counts reach a threshold of three to five stinkbug catches per 10 sweeps from each sample location. During the second two weeks, treatment thresholds increase to 10 stink bugs per 10 sweeps.

“You have to be aware that once you treat, you need to follow up and make sure those stink bugs stay down and don’t reinfest the field,” Johnson says. “Immatures can still hatch out and become a subsequent problem after the first treatment.”

Pulling the trigger
Growers have a choice of treating with a pyrethroid, such as Karate or Mustang Max, or using methyl parathion, which provides quick knockdown at a typically lower cost but lower residual control.

Johnson says he has studied tankmixes of methyl and Karate or Mustang Max at lower rates and found good preliminary results in small-scale trials. He believes the tankmix may provide broader coverage against both the adult and immature stages of the pest.

Castro typically recommends making the first application with a pyrethroid because it provides residual activity of four to five days, compared to about two days with methyl or other knockdown products.
Then follow about a week later with methyl for a second application, if necessary, based on sweep counts that should resume about four days after the first treatment.

Johnson’s studies in Arkansas have shown that rice stink bugs move to lower portions of the plant during the heat, so sweep net sampling is most accurate during cooler hours. And treatments are most effective in the morning and evening when chances are higher of direct contact between the insecticide and the pest.

Last year, some Louisiana growers made up to six insecticide applications, so Johnson emphasizes the importance of rotating chemistries to avoid creating resistance among resident insect populations. “We always recommend alternating products,” he says.

Morgan says he often begins his treatments on levees or field perimeters where rice is more advanced or infestations are higher, sometimes getting by with a spot treatment on about 10 percent of the field. The practice buys time before he returns with a full application to the entire field.

“With GPS on the planes, we can also do an application where we’re treating only 50 percent of the field and applying the other 50 percent a week later, so we can treat hot spots, clean up the edges and then hang in there and monitor the whole crop until the entire field reaches treatment thresholds,” Morgan says.

Pay now or pay later at the mill
Regardless of the strategy, Morgan says rice stink bug control is a small investment compared to the damage it can exact on the crop and something growers should take seriously.

“Milling goes down, peck goes up and gross production goes down, so it’s imperative you manage stink bug,” he says. “And it’s at the end of the crop when you already know how much money you have in it. I mean why would you put $250 into a crop and pinch the last 10 bucks?”

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

Stink bug intervention Monitor early and manage grasses for control
By Marni Katz
Rice stink bug is an increasing concern across the Southern rice-producing regions, delivering a one-two punch on both yield and quality in heavy infestation years. “As far as insects are concerned, rice stink bug is the No. 1 pest in rice in Arkansas,” says Don Johnson, an entomologist with the University of Arkansas Extension Service in Little Rock. “The last several years, stink bug has been our major pest because it can have such an impact on the yield and quality of the crop.” Rice stink bug is also quickly becoming the leading insect pest of Texas rice producers and is second in Louisiana, only to the rice water weevil. In 2001, the heaviest rice stink bug year in memory, Johnson says the insect caused an estimated $25 million to $30 million in crop losses in Arkansas, with virtually every acre of rice in the state requiring treatment. Typically, however, about one-third to one-half of the state’s rice is treated for stink bug, at a cost ranging from $5 to $8 per acre. One or two applications are often enough to control an average outbreak. Tiny bug, big losses Unmanaged, though, stink bug can cause an estimated 10-percent yield loss in a given season, not to mention losses due to impacts on quality. Stink bug can damage rice throughout heading, and growers must be diligent prior to heading and throughout the period the crop is vulnerable, says Boris Castro, a rice Extension entomologist with the Louisiana State University’s Department of Entomology in Baton Rouge. During the first two weeks after heading, rice stink bug will directly reduce yield by feeding on the panicle of flowering rice heads, killing embryos and destroying kernels. From two weeks after heading until the head starts to dry down, stink bug continues to threaten the crop’s quality by leaving an opening for pathogens that can lead to rice peckiness or staining. Control grassy vegetation Castro says an integrated rice stink bug management program actually begins by controlling grassy weeds in rice fields and along roads, levees and borders. That’s where stink bug populations overwinter and build before moving into the preferred flowering rice as grasses begin to dry down. “The best way to keep these populations low is to control grassy weeds throughout the season,” he says. “If growers allow grasses to mature, they can make the whole thing worse by driving them into rice later. It’s better to do a top job controlling those grasses and then start monitoring the field early when you have 50 to 75 percent heading. A fully integrated program Morgan Smith, who grows and manages more than 3,000 acres of rice in northern Louisiana’s Richland and Ouachita parishes, says rice stink bug management is an integrated program of monitoring, treatment and managing grassy weeds in the field and along the perimeter and even in other crops such as corn and soybean, which can provide an overwintering habitat for the pest. “The first stage of stink bug management is to have good herbicide management in your crop so that you don’t have host plants for the bugs before the rice heads,” Smith says. “Take care of your barnyardgrass or your sprangletop and also manage your ditch banks.” Smith often tankmixes an insecticide with herbicides when spraying grasses on perimeters and roads to kill overwintering insect populations and keep them from migrating into rice at heading. Monitor to time treatments As heading approaches, monitoring the rice field becomes the primary component in rice stink bug management to keep pest levels under control as they reach treatment thresholds. Treatment thresholds are based on sweep net counts, although current research is underway to determine if an economical monitoring trap is also feasible to improve early monitoring along the field periphery. “Monitoring is very important because growers need to be aware of the presence of insects even before rice starts heading out,” Castro says. Start sweeping rice fields at about 50 percent to 75 percent head emergence, taking 10 sweeps from up to 10 representative locations within the field. Sweep net thresholds for the pest are much lower during the first two weeks of heading when yield damage is most likely. Castro recommends treating during the first two weeks when sweep net counts reach a threshold of three to five stinkbug catches per 10 sweeps from each sample location. During the second two weeks, treatment thresholds increase to 10 stink bugs per 10 sweeps. “You have to be aware that once you treat, you need to follow up and make sure those stink bugs stay down and don’t reinfest the field,” Johnson says. “Immatures can still hatch out and become a subsequent problem after the first treatment.” Pulling the trigger Growers have a choice of treating with a pyrethroid, such as Karate or Mustang Max, or using methyl parathion, which provides quick knockdown at a typically lower cost but lower residual control. Johnson says he has studied tankmixes of methyl and Karate or Mustang Max at lower rates and found good preliminary results in small-scale trials. He believes the tankmix may provide broader coverage against both the adult and immature stages of the pest. Castro typically recommends making the first application with a pyrethroid because it provides residual activity of four to five days, compared to about two days with methyl or other knockdown products. Then follow about a week later with methyl for a second application, if necessary, based on sweep counts that should resume about four days after the first treatment. Johnson’s studies in Arkansas have shown that rice stink bugs move to lower portions of the plant during the heat, so sweep net sampling is most accurate during cooler hours. And treatments are most effective in the morning and evening when chances are higher of direct contact between the insecticide and the pest. Last year, some Louisiana growers made up to six insecticide applications, so Johnson emphasizes the importance of rotating chemistries to avoid creating resistance among resident insect populations. “We always recommend alternating products,” he says. Morgan says he often begins his treatments on levees or field perimeters where rice is more advanced or infestations are higher, sometimes getting by with a spot treatment on about 10 percent of the field. The practice buys time before he returns with a full application to the entire field. “With GPS on the planes, we can also do an application where we’re treating only 50 percent of the field and applying the other 50 percent a week later, so we can treat hot spots, clean up the edges and then hang in there and monitor the whole crop until the entire field reaches treatment thresholds,” Morgan says. Pay now or pay later at the mill Regardless of the strategy, Morgan says rice stink bug control is a small investment compared to the damage it can exact on the crop and something growers should take seriously. “Milling goes down, peck goes up and gross production goes down, so it’s imperative you manage stink bug,” he says. “And it’s at the end of the crop when you already know how much money you have in it. I mean why would you put $250 into a crop and pinch the last 10 bucks?” For questions or comments about this article, contact Rice Farming editor Vicky Boyd at (209) 571-0414 or vlboyd@att.
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