Pink Bollworm


Pink BollwormPink Bollworm (PBW), also known as Pinky, is an insect pest, a moth, that infests cotton. The adult moths lay eggs on cotton bolls. When the eggs hatch, the larvae damage cotton bolls and squares by burrowing into them. The cotton seed is destroyed, and the lint is cut and stained. The larvae take on pinkish bands as they mature, hence the nickname Pinky. Cotton growers in areas infested with PBW must increase inputs into the cotton crop to combat PBW. Okra is also a host of PBW. PBW was first detected in Texas in 1917. It is thought to have arrived from northern Mexico naturally or through infested shipments.

The Program

The PBW Program is one of the most successful and longest running, area-wide integrated pest control programs in the world. The program has been in operation since 1967. The program is funded almost entirely by assessments on each bale of cotton produced by California cotton growers. The United States Department of Agriculture (USDA) also contributed funds to the program. The program has prevented infestations of PBW from becoming established in California cotton growing regions. The program utilizes a multi prong approach to eliminate PBW. This includes sterile moth release, insect trapping, mating disruption, a host free period, and 100 percent transgenic Bacillus thuringiensis (Bt) cotton in Southern California. The California Department of Food and Agriculture (CDFA) deploys pheromone baited insect traps in cotton growing areas. A pheromone is a substance secreted by the female moth to attract the male. A synthetic pheromone is used in the trap. Sterile moths are reared at a CDFA/USDA PBW Rearing Facility in Phoenix, Arizona. The sterile moths are released by aircraft over areas where the insect traps indicate the need. Occasionally the pheromone will be applied to an area. The moths are then unable to find each other to mate. The host free period refers to a period of time in which the host plant, in this case cotton, may not be grown.


The Department enforces cotton plow down regulations to maintain grower compliance with the host free period. Cotton plantings must be destroyed by a specific date. The destruction includes the shredding of cotton stalks, dislodging the cotton roots from the soil and incorporation into the soil. There must be no regrowth. In Fresno County, cotton must comply with plow down regulations by December 20 for plantings south of Shields Avenue and by December 31 for plantings north of Shields Avenue. No cotton may be planted in Fresno County until March 10 of the next year. Department staff survey every cotton field in Fresno County every year to confirm compliance with plow down requirements. The Department is authorized to issue civil penalties to any person not complying with plow down(PDF, 157KB) requirements or planting date restrictions.

Because this program has been so successful, CDFA usually issues a special permit each year to allow for reduced tillage. Reduced tillage can be used in areas where PBW was not detected the previous season. Cotton growers must submit a reduced tillage form(PDF, 18KB) to the Department ten days prior to beginning the use of reduced tillage. The form serves to notify the Department of their intent to use reduced tillage and gives the Department time to verify reduced tillage is allowed in the area requested. The Department mails a letter and the reduced tillage form to cotton growers each year. The letter notifies cotton growers of the eligible reduced tillage areas. Cotton growers approved for reduced tillage must comply with all the previously stated requirements except that the cotton crop residue does not have to be incorporated into the soil. Reduced tillage permits can be submitted to any of the Departments’ district offices, faxed or mailed to the main office.

The Goal

Former U.S. Secretary of Agriculture Sonny Perdue proclaimed U.S. cotton to be free of PBW in October of 2018 (see Eradication of Pink Bullworm Proclamation). PBW had cost cotton producers tens of millions of dollars yearly in control costs and yield losses. Despite this proclamation, California requirements are still enforced. PBW is an invasive pest and the strategies used to eliminate the pest must remain in place to ensure no resurgence occurs. The Department will continue to enforce plow down requirements and asks growers to remain vigilant in compliance with the plow down requirements.