Billbug pressure is a challenge for many row rice farmers in the Delta, and the best protection against the pest begins at planting with an insecticide seed treatment, like Fortenza or Dermacor. But what can a farmer do if billbug pressure sneaks in mid-season, and the seed was not treated with a diamide? 

To get answers, Farm Press talked with Extension Crop Protection Specialist Chase Floyd at the University of Missouri. He said, “Controlling billbugs with a foliar application has a lot more to do with luck than it does precision.” 

Additionally, Extension Entomologist Nick Bateman at the University of Arkansas System Division of Agriculture, discussed the pest during his presentation at the National Conservation Systems Cotton and Rice Conference in January.  

Together, Floyd and Bateman lent their insight and expertise in the battle against rice billbugs. 

Billbugs overwinter 

Floyd conducted four years of billbug research in Northeast Arkansas during his graduate studies at the University of Arkansas. Bateman referred to results that determined a greater threat when row rice fields had bermudagrass at the turnrow.  

“Basically, what we found is if you have good bermudagrass on your turnrows, you are a lot more susceptible to having billbug pressure,” Bateman said, noting that billbugs overwinter in bermudagrass until the rice reaches plant growth of one- to two-tillers. 

Related:Insect problems emerge as row rice acreage increases

Floyd added that billbugs are unique because they overwinter as both adults and larvae. “This means the initial feeding we find in the field early-season is likely adults that overwintered,” he said. “The billbugs that overwinter as larva all emerge at different times depending on what stage they overwintered.” 

Furthermore, Floyd hypothesized from his dissertation data that billbugs have five larval instars, which means five emergence timings. 

“You are essentially looking at a five-week window where billbugs are actively moving in the field and laying eggs. That is the reason foliar insecticide applications are essentially ineffective,” Floyd explained. 

“The cheaper products are typically contact insecticides, so droplets must physically touch the insect. They also lack residual, so you would have to make weekly applications for five weeks, and still would not get 100% billbug control.” 

Floyd said more expensive options are systemic insecticides, but those should be moving through the plant before billbugs begin to feed and oviposition. He noted, those products are too expensive to go out on a weekly schedule. 

Related:Rice stinkbug: Resistance, strategies, and net return

Options for in-season billbug control 

So, if billbugs show up in your furrow-irrigated rice fields and you did not use a diamide seed treatment, what can you do? 

Bateman said from a foliar perspective, Prevathon or Vantacor can provide some control if applied at the right time. He reported trial results with sprays at two- to three-leaf, first and second tiller, and fourth and fifth tiller – all the way to green ring. 

“Basically, we sprayed every couple of weeks. Around the first tiller it seemed to do okay.”  

Beyond that, Floyd said the best thing you can do is keep an eye on the billbug population and plan for next year. “We tell growers to scout those fields, monitor the billbug populations, and record your yield this year. If you have high levels of billbug this year, make sure you have a more effective seed treatment in your budget for next season.” 

Floyd recommends walking the field to scout for damaged tillers, and count those that will never have a head come to fruition. Then, scout again before harvest. 

“Count a couple of five-row feet samples at harvest and see how many blanks you have. Those numbers plus the damaged tillers from earlier in the season will compound and you can see how much yield was left in the field,” Floyd explained. 

Another tip to reduce billbug injury is to keep standing water on the field, closer to the water level for paddy rice. “I understand this is not a viable option for all growers,” Floyd added.  

“However, standing water will force billbugs to go into a hibernation state where they are not feeding. The water will not kill them, because they are not truly hydrophobic, but it can reduce injury.” 

Finally, as the rice dries down before harvest, pick up the poly pipe on the top end of the field. Floyd said the adult billbugs will begin to migrate back to the bermudagrass to overwinter.  

“I have walked with several growers who were shocked when I pulled up the poly pipe and showed them how many billbugs were out there that year.” 

While Floyd said nothing indicates increased billbug pressure in 2024, the insects will continue to solidify themselves as a major pest in furrow-irrigated rice as the popularity of the practice gains traction. 

Plan for next year 

Ultimately, Bateman said the jury is still out on exactly how damaging billbugs are, but a diamide seed treatment provides the most effective control. 

“The only consistent thing we saw was adding Dermacor or Fortenza to that seed, and it is not bulletproof by any means. We saw about a 60 to 70% reduction in injury,” Bateman reported. 

“What does that equate to in a combine? We have yet to find anything to zero billbugs out to know what their yield loss potential is, but I can tell you, multiple times we saw anywhere between a 15- and 25-bushel increase.” 

Bateman said overtreating a hybrid rice seed with Fortenza pays for itself at up to $8 per acre. As for Dermacor, the seed treatment is closer to $12 per acre on a hybrid. 

For those in the 60-pound range on conventional rice, Bateman said the seed treatment ranges from $16-17 per acre. 

Additionally, Fortenza combats rice water weevil, so the protection is two-fold. “Rice water weevil is the number one insect rice farmers deal with, particularly in flooded rice,” Bateman said. “Fortenza is about the best safety net you have there.”