Linda F. Benedict, Davis, Debra T., Stout, Michael J.
Bryce Blackman, Troy Autin, Natalie Hummel, Anna Mészáros, M.O. Way, Michael Stout and Debra Davis
Knowing how producers adopt new production practices is vital to research and program planning. Production practices in Louisiana rice have changed dramatically over the past decade. For example, herbicide- tolerant Clearfield varieties are now planted on nearly 60 percent of rice acres annually, the use of drill-seeding and hybrid varieties has increased, and seeding rates have decreased.
During this same period, the most important change in insect pest management has been the introduction of insecticidal seed treatments for managing the rice water weevil, an early-season pest that is consistently a major yield-reducer. The three currently available seed treatments are Dermacor X-100, CruiserMaxx Rice and NipsIt INSIDE. These seed treatments are effective against the rice water weevil and help protect the investment in expensive Clearfield and hybrid seed. In addition to new seed treatments, new insecticides have been introduced for managing the rice stink bug, which is the major late-season pest of Louisiana rice.
From 2008 to 2012, annual surveys were conducted to determine pest management practices in the rice industry in Louisiana and surrounding rice-producing states. Questions focused on sampling practices, insecticide use patterns and management actics. Following each growing season, surveys were distributed during production meetings, through email and via a rice insect blog. Over five years, 851 surveys were completed from five states, with the majority (86 percent) from Louisiana and Texas. Survey respondents identified themselves as rice farmers (62 percent), consultants (20 percent), dealers (4 percent), and others, including extension agents and industry representatives (15 percent).
The average Louisiana respondent had more than 31 years of experience in rice production. More than 50 percent of farmers in Louisiana and Texas selected print media, consultants and production meetings as their top sources of information on integrated pest management practices (Figure 1).
The presence of rice water weevils in fields was reported by approximately 90 percent of respondents across all years. Respondents were asked to note tactics used against rice water weevils in one or more of the fields for which they were responsible (Table 1). Less than 10 percent of respondents used no management tactics. Responses showed that seed treatments were rapidly adopted after the introduction of Dermacor X-100 in 2008, and seed treatments of Dermacor X-100 and CruiserMaxx Rice were the most widely used management tactics in the last two 14 Louisiana years of the survey. The increase in the use of seed treatments corresponded with decreased use of pyrethroid insecticides and a reduction in draining of fields for weevil control from 43 percent in 2008 to 18 percent in 2012. Factors that likely contributed to the rapid and widespread adoption of seed treatments include ease of use and effectiveness against the rice water weevil and minor pests.
Respondents observed rice stink bugs in 79 percent to 89 percent of their fields over the survey period. More than 90 percent of respondents sampled for stink bugs from 2009 to 2012. Approximately 35 percent of farmers in Louisiana reported not spraying for stink bugs from 2009 to 2012, while 46 percent sprayed once per season. Only 14 percent of Louisiana farmers made two pesticide applications for rice stink bugs, and less than 5 percent sprayed three or more times. The majority of respondents treated their crops with the pyrethroid insecticides Karate Z or Mustang Max, while some respondents used the organophosphate insecticides malathion and methyl parathion (Figure 2). Recently, LSU AgCenter entomologists showed that after 50 years of use, malathion is ineffective against rice stink bugs, and methyl parathion use in rice is no longer allowed by the U.S. Environmental Protection Agency. Respondents chose not to alternate chemistries from one year to the next. During the survey period, a new insecticide, Tenchu 20SG (a neonicotinoid), was tested against rice stink bugs and shown to be as effective as Karate Z. Use of Tenchu 20SG grew from 8 percent in 2011 to 16 percent in 2012 before receiving a full label in 2013 after the survey ended.
These surveys provide a valuable picture of producer practices while highlighting a need for more options for managing rice pests. Repeated use of insecticides in the same chemical class eventually will lead to insecticide resistance in the target insect. Heavy reliance on Dermacor X-100 for rice water weevil control and pyrethroid insecticides for rice stink bugs is cause for concern from a resistance management standpoint. Additionally, the use of draining fields to combat rice water weevils must be reexamined to ensure that it is cost-effective.
Even as more resources become available on the Internet, the use of print media and face-toface meetings remain important to rice farmers. This survey demonstrates the continuing need for extension personnel to communicate relevant research to producers in person and through print publications.
Acknowledgments: The authors are grateful for the support of numerous extension agents and rice industry participants. This survey was supported in part by the Louisiana Rice Research Board and the USDA Southern Region IPM Program.
Bryce Blackman, a former graduate assistant in the Department of Entomology, is an agronomy extension and training specialist at the International Rice Research Institute, Los Banos, Laguna, Philippines; Troy Autin is a graduate assistant in the LSU School of Human Resource Education & Workforce Development; Natalie Hummel is with Bayer Crop Science, Greenville, N.C.; Anna Mészáros is with Pest Management Enterprises, Cheneyville, La.; M.O. Way is a professor at the Texas A&M AgriLife Research and Extension Center, Beaumont, Texas; Michael Stout is a professor in the Department of Entomology; Debra Davis is director and professor in Organizational Development and Evaluation.
This article was published in the summer 2014 issue of Louisiana Agriculture Magazine