The post-eradication phase of the boll weevil eradication program in Oklahoma will not officially begin until the State Board of Agriculture designates the state as an "eradicated area," according to Joe Harris, director of the Oklahoma Boll Weevil Eradication Organization.
Based in Hobart, Okla., in Kiowa County, Harris' office oversees the eradication program that extends to all counties where cotton is grown.
As Oklahoma approaches a post-eradication phase in the program, a success story in itself, it is important to understand what post-eradication means to Oklahoma farmers, Harris says.
"The purpose of the post-eradication phase is to ensure against weevil re-infestation in areas declared free of the insect. Without post-eradication monitoring of cotton fields, the potential for re-infestation in as little as one season is very real. This potential is related to the boll weevil life cycle."
Harris explained although research concerning the boll weevil life cycle varies with regard to the timeline of early stages of development, there is general agreement weevils can live about 44 to 55 days (30 or more days as an adult), except for late season weevils which can overwinter and still be alive in the spring.
Pregnant female weevils that overwinter can stay alive until cotton plants begin to put on young fruit (squares) and lay an average of 200 eggs. These eggs can become breeding adults in 21 days.
Depending on field conditions, four to five to as many as eight to 10 generations of weevils can be born in one growing season. And just one pair of undetected weevils can generate 12 million offspring, although 2 million is more typical, Harris said.
"Early detection, along with timely and appropriate response in post-eradication, breaks the boll weevil life cycle. This significantly reduces the threat of major re-infestations in previously eradicated areas. We have seen examples of this re-infestation in several Southeastern states between 1995 and 1998. Addressing each outbreak costs producers several thousand dollars, up to 2 million for the worst case.
"In the latter example, the core field where the problem started had been weevil-free for five years. These re-infestations confirmed the need not only for long term monitoring of eradicated areas, but also the need for a strong quality assurance program to make sure insect traps are inspected in a timely manner and that suspect insects are brought in from the field for proper identification."
Quality assurance is an important part of a post-eradication program, Harris said. Post-eradication monitoring and response follows a set of nationally-accepted "minimum standards" developed by the National Cotton Council Boll Weevil Committee working with the USDA Animal and Plant Health Inspection Service (APHIS) and state eradication program managers, he said.
These standards are based on more than 50 years of eradication research, protocol development and field experience dating back to 1958. Prior to this time, emphasis had been on suppression of the weevil rather than elimination of the insect from the United States.
"As a review of the total elimination or eradication process," Harris said, "and based on the number of weevils caught in a given season, active eradication flows into a period of transition, which leads to post-eradication.
"In active eradication, insect traps are placed at one to five acre intervals around cotton fields and are checked every week. Trap lines set up along highways monitor for hitchhiking weevils on trucks and other vehicles. The treatment trigger is one catch on a field and additional traps may be deployed in or around that field and adjoining fields. Traps are checked every three days with follow-up spraying of the triggered field and adjoining fields if additional weevils are caught."
During transition, Harris explained, using minimum standards, traps are placed at increased intervals on roads running by cotton fields and highway trap lines are continued. Traps are checked every two to three weeks. The interval in Oklahoma in 2009 was variable by area from one trap to 40 acres up to one trap for an 80-acre field. If a suspect weevil is caught in a field, it must be positively identified by a certified person.
Within 24 hours additional traps will be deployed at active eradication intervals on all cotton fields within a one mile radius of the original trap. The traps will be checked daily for at least three days if the catch is confirmed to be positive, then weekly until the crop is harvested. The treatment trigger for that and adjoining fields is a second weevil caught in the area of intensified trapping.
"In post-eradication," Harris said, "weevil capture and response protocol remains the same as during the transition period. However, as the threat of re-infestation decreases over time, traps may be placed at greater intervals. A few East Coast states with long post-eradication histories are now grid trapping in some areas, that is, one trap to any quarter-section (160 acres) with cotton regardless of the number of cotton fields. Traps are checked at least every three weeks because of the weevil's average growth and maturation cycle of egg to adult in 21 days."
Any state either transitioning to or officially engaged in post-eradication activities is required to adhere to the minimum standards protocol, Harris said. States transitioning at the present time include Oklahoma, Arkansas, Missouri, Tennessee, Mississippi, and Louisiana.
All states, Harris said, are expected to be declared weevil free and officially enter post-eradication no later than 2010. Although Texas, Harris said, is mostly weevil free and is in transition in several different zones within the state, three areas in the central and southern parts of Texas with continuing boll weevil reproduction may remain in active eradication for some time.
Ten eradicated states have been in post-eradication for several years, Harris said. They are: Virginia, 25 years; North Carolina, 22; South Carolina, 19; Arizona, 18; California, 18; Georgia, 17; Florida, 15; Alabama, 9; Kansas, 7 and New Mexico, two years.
North Texas, Oklahoma and Kansas Cotton (NTOK) is a group of farmer cooperatives, Land Grant Universities and private companies dedicated to the expansion of cotton production in North Texas, Oklahoma and Kansas.