Date of this Version
Blackbird damage to sprouting rice can be locally severe and costs Louisiana growers an estimated $4 million/year and Texas growers $4.4 million/year. DRC-1339 blackbird baiting programs probably will continue until available alternative control techniques (i.e., repellents) become available. We conducted 3 studies to evaluate different rice baits and chemicals to improve efficacy of DRC-1339 for use at staging areas. During the first study, individually caged red-winged blackbirds preferred untreated medium grain brown rice over long grain brown rice, rough rice, or rough rice soaked with sodium bisulfite. Of birds offered only medium (control), long, rough, and rough rice soaked with sodium bisulfite treated with 2% DRC-1339 diluted 1:25 with untreated carrier (medium, long, or rough rice), 90 to 100% died within 48 hrs. During the second study, individually caged red-winged blackbirds preferred untreated rice over rice treated with Harvest Guard or ethyl cellulose. Birds were offered only medium brown rice (control), Harvest Guard, or ethyl cellulose-treated medium brown rice treated with 2% DRC-1339 diluted 1 :25 with untreated medium grain brown rice. With the medium grain brown rice (field bait), 100% mortality was observed within 48 hrs. With the Harvest Guard and ethyl cellulose treatments, 580% mortality was observed. The third study was an aviary test to determine if aging the chemical baits (sodium bisulfite, Harvest Guard, ethyl cellulose) for 3 days in Louisiana would affect mortality. Mortality with the fresh field and sodium bisulfite baits were 100%. We did not achieve 280% mortality with either the fresh Harvest Guard or ethyl cellulose bait. Mortality with the aged sodium bisulfite bait was 50%. None of the other aged baits produced >l0% mortality. Degradation occurred with all the aged baits but occurred the least with the sodium bisulfite treatment. Future research will look at possibly combining sodium bisulfite with W protection to further reduce the degradation of DRC-1339 in the field.