A large-scale boll weevil eradication program was initiated in Texas in an effort to rid the state of the cotton boll weevil, Anthonomus grandis Bohman. The cotton growing area in the state has been divided into nine zones, each encompassing between 150,000 and 3.9 million acres of cotton. The plan is to complete the eradication of the boll weevil within the next 10 years.

The program was first initiated in the Southern Rolling Plains (SRP) on 200,000 acres of cotton in September of 1994 with the diapause phase. All cotton fields in the SRP received a single application of malathion ULV during the week of September 26, and every week thereafter until all hostable plants and food supply were eliminated by harvesting and stalk destruction or a killing freeze. The total cumulative number of acres treated was 866,363, averaging 4.3 applications per acre. For evaluation purposes prior to the first application, boll weevil traps were placed at a density of one trap per five acres around the periphery of 22 randomly selected fields. Traps were inspected weekly.

The season-long phase of the program was initiated during the spring of 1995. Boll weevil traps were placed during planting around all cotton fields at a density of one trap per five acres and were inspected on a weekly basis. A single malathion ULV application was made to fields that had reached the treatment criteria (action threshold). The threshold was trap catch of two adult boll weevils per field at matchhead square. The action threshold was increased to eight adults per field beginning August 7 in an effort to reduce the use of insecticide during mid-season, and decreased to five adults per field beginning September 18 for the remainder of the season. The total cumulative number of acres treated season long was 1,862,522 acres, averaging 8.5 applications per acre. The overall mean number of boll weevils captured per trap during the fall of 1995 was significantly less than 1994. The 1995 mean was 2.7 and the 1994 mean was 50.6, a reduction rate of 94.7%.

In the spring of 1995, the program was initiated in the Lower Rio Grande Valley (LRGV) on 365,000 acres of cotton with the season-long phase. Cotton fields received two malathion ULV applications (at 7-9 day intervals) when the initial action threshold was reached. One additional application was made on each subsequent occasion that the threshold was exceeded. The action threshold was increased to five adults per field in mid-season (June 12), and to10 in the latter part of the growing season (July 3). The total cumulative number of acres treated season long was 1,928,164 acres, averaging 5.4 applications per acre. With 1995 being the first year of the program, there was no program trapping data collected from the previous year for comparison as was the case in the Southern Rolling Plains. Definite conclusions may not be made until comparative data is collected in 1996.

These results demonstrate that the area-wide eradication approach, utilizing pheromone traps with sound cultural, mechanical and chemical controls, represents an effective strategy in reducing the boll weevil populations as planned and subsequently eliminating the pest.