Expect no curtain call for the pink bollworm, the most pernicious pest in southwestern desert cotton fields.
Eradication of the pinkie is near, but not a done deal in Texas, New Mexico, Arizona, and California. Northern Mexico has made tremendous strides in eradication.
For more than four decades, PBW has been kept out of California’s San Joaquin Valley with an aggressive trapping program to monitor it and dropping millions of sterile pink bollworm moths to overwhelm native populations.
Wally Shropshire of Blythe, Calif., the 84-year-old chairman of the California Cotton Pest Control Board, said the success of the eradication program in Far West Texas and Arizona has put PBW on the fast track to eradication.
“We are 99.8 percent there,” said Shropshire. “The eradication program has been a great success with the combination of the pheromones, sterile moth releases, and Bt cotton.”
Another factor has been plow down rules to prevent overwintering.
So far this year, there have been no native moths trapped in the San Joaquin. Last year by this time there were 29 trapped. When natives are trapped, program managers bombard the find areas with more steriles.
“We have had only one native find in Southern California,” Shropshire said. “I am sure (the eradication program) has had an impact on the zero finds this year in the San Joaquin.”
Other instrumental warriors in PBW eradication include: Larry Antilla, director, Arizona Cotton Research and Protection Council (ACRPC), Phoenix, Ariz., and entomologist Robert Staten, retired director, USDA-APHIS Methods Development Laboratory in Phoenix.
“I think by the end of 2010 we’ll have most of New Mexico, West Texas, Arizona, and Mexico’s state of Chihuahua largely un-impacted by the pink bollworm,” Staten said. “We are down to finishing and conquering the pink bollworm in the Mexicali, San Luis, and Yuma valleys.”
Far West Texas added the pinkie fight to its boll weevil eradication efforts in about 2001. Arizona was the last state to launch eradication in 2006.
Staten and Antilla concur the single most potent weapon has been Bt cotton.
“If we didn’t have high levels of Bt planting today we would not be this close to eradication,” Antilla said.
Antilla, working with the ADA and others, successfully lobbied the Environmental Protection Agency to grant a 24c special use registration to allow 100 percent Bt plantings in all Arizona eradication zones without a refuge area.
This allowed Bt cotton to be seeded to 97 percent of Arizona’s acreage, up from 80 percent to 85 percent before the exemption.
The sterile moth component is another pivotal piece of the eradication puzzle.
From 2006-2009, about 19 billion steriles were dropped by small plane on cotton fields across the four-state area plus Mexico.
A glitch occurred last August when about 350,000 moths missed the irradiation (sterilization) process. The fertile moths were mixed with 2.1 million steriles loaded into a single airplane’s drop machine. The fertile-sterile mix was dropped over the Fabens, Texas, area east of El Paso.
“We quickly responded with a pheromone rope treatment and future sterile releases in the area. There is no evidence of pinkie reproduction in the Fabens area this year,” Staten explained.
Far West Texas is nearing a decade in pinkie eradication. The El Paso/Trans Pecos area includes about 37,000 acres of cotton and about 3,600 PBW traps. The last trapped native moth was found in November 2009. The last larva was found in 2007.
Eradication is proceeding as planned in the El Paso/Trans Pecos corridor, said Larry Smith, program director, Texas Boll Weevil Eradication Foundation in Abilene.
Last year's fertile moth release in the Fabens area (about 7,500 acres of cotton) was a concern.
In response to the fertile moth drop, the foundation directed most of the available steriles for the area to be dropped in the Fabens area. Pheromone rope was placed on cotton plants from south of Fabens to the El Paso city limits.
"The El Paso/Trans Pecos area was essentially eradicated until the fertile moth drop," Smith said. "It looks like our efforts with the extra steriles and rope are paying off. We have not caught a single native moth in this area this year."
New Mexico has about 30,000 acres of cotton statewide. Joe Friesen, program director, South Central New Mexico Pink Bollworm Control Committee, Las Cruces, manages PBW eradication in the southwestern counties of Dona Ana, Luna, and Sierra (13,000 cotton acres). The tri-county area is in the monitoring phase.
Friesen reports the last native adults were caught in 2007. The last larva found in a cut boll was in 2004.
“To have zeroes is a good feeling,” Friesen said. “We’ve been able to knock them out. If we can hold our ground, things will be fine.”
Arizona cotton growers passed a referendum in 2004 that requires eradication in each of Arizona’s three eradication zones within four years.
“We have a statutory timetable, not a biological timetable,” Antilla said. “Thanks to the effectiveness of the tools available, the two timetables have coincided.”
About 4,000 traps statewide are checked weekly.
Area One eradication was launched in eastern and central Arizona counties in 2006. Formal eradication was completed last year. Monitoring, sterile moth releases, and trapping continue.
“We caught 207,000 natives in traps in Central Arizona in 2006; so far we have 8 captures in 2010,” Antilla said. “We haven’t found a larva since 2008.”
Area Two eradication was kicked off in 2007 in La Paz and Mohave counties, which border the Colorado River. There are no native captures or evidence of reproduction. Area 2 also includes the southern California counties of Riverside, San Bernardino, and Imperial.
Areas One and Two have a 99.99 percent reduction in pinkies to date, Antilla says. This year is the final year for Area 2 eradication.
Area Three eradication was launched in 2008 in Yuma County. Moth captures have declined 99.4 percent.
“I hope to have no reproduction in Yuma County by the end of this year,” Antilla said. “Year four (2011) would basically include cleaning up and maintaining maximum trapping and sterile moth releases.”
Mexico has done a good eradication job so far, Staten says. “We have not found a single larva in the State of Chihuahua for three years.”
Achieving eradication of the pink bollworm in desert cotton is close.
Antilla says PBW eradication will open new doors for farmers to experiment with non-Bt cotton varieties to increase yields and lower the current $32/acre technology fee farmers pay for Bt cotton.
As eradication nears, the National Cotton Council (NCC) will likely develop a generic eradication definition to fit the cotton states. NCC PBW committees consisting of growers and professional advisers must approve the definition. Official declarations will likely be declared by state governments