Pesticide Note

North Carolina Cooperative Extension Service
North Carolina State University



Pesticide Note Number 2
ENT/pia-2
February 1995

Insecticide Use by North Carolina Cotton Growers in 1992




Stephen J. Toth, Jr., Extension Pesticide Impact Assessment Specialist

Jack S. Bacheler, Extension Cotton Entomology Specialist


Caution!
The information and recommendations in this Note were developed for North Carolina and may not apply in other areas.




Introduction

In 1992, cotton growers in the state harvested 468,000 bales of cotton from 377,000 acres, ranking North Carolina eleventh among the states in cotton production (Watson 1993). The value of cotton lint produced in North Carolina in 1992 was $129 million, while the value of cottonseed produced in the state was $15.7 million.

Cotton is very susceptible to damage by insects. These pests can reduce yields from 25% to over 75% (Bacheler 1993). Insect pests of cotton in North Carolina include thrips, aphids, plant bugs, bollworms (corn earworms), tobacco budworms, European corn borers, beet and fall armyworms, cabbage and soybean loopers, and stink bugs. One of the most damaging insect pests of cotton in the United States, the boll weevil, has been eliminated in North Carolina as a result of the Boll Weevil Eradication Program which began in the state in 1978. Thus, North Carolina cotton growers do not treat their acreage with insecticide to manage this pest.

A mail survey of cotton growers in 18 counties in North Carolina was conducted in the winter of 1993 to determine the use of pesticides on the 1992 cotton crop. The use of insecticides and non-chemical pest management practices by survey respondents in 1992 is reported.


Survey Method

Cotton-growing counties in North Carolina were placed in five agronomic regions. Within each region, 50% of the counties with 1,000 or more acres of cotton in 1992 were selected at random for participation in the survey (Fig. 1). County mailing lists of cotton growers were obtained from the North Carolina Department of Agriculture and reviewed for accuracy by agricultural extension agents. All cotton growers identified in the selected counties were included in the survey.

A total of 1,115 growers in Carteret, Chowan, Columbus, Duplin, Halifax, Hertford, Johnston, Lenoir, Nash, Onslow, Pamlico, Perquimans, Richmond, Robeson, Sampson, Scotland, Union and Wilson Counties were surveyed by mail in the winter of 1993, following methods described by Christenson (1975) and Dillman (1978). On February 16, a cover letter signed by the county agricultural extension agent, questionnaire, and pre-stamped return envelope were mailed from the county extension centers to each cotton grower. On February 23, a postcard from the agent was mailed to each grower as a reminder to complete and return the questionnaire. Finally, on March 9, another letter, questionnaire, and return envelope were mailed to each grower not responding to the previous correspondence. Information collected from growers was compiled and analyzed at North Carolina State University.

Figure 1

Fig. 1. North Carolina counties (hatched) selected from 5 cotton-growing regions for participation in the mail survey of cotton growers.


Results and Discussion

Cotton Production. Of the 1,115 cotton growers that were surveyed, 755 or 67.71% responded. A total of 605 respondents planted 155,640.81 acres of cotton in 1992, while the remaining 150 respondents did not produce a cotton crop (i.e., no crop, leased farm, or deceased). Of the cotton acreage planted by survey respondents, 7,775.60 acres were grown no-till (5,293.6 of these acres were in Halifax County). Cotton growers responding to the survey harvested 151,556 acres of cotton in 1992, with an average yield of 632.46 pounds of lint per acre. The average yield of growers statewide in 1992 was 596 pounds of lint per acre.

Thrips and Aphids. Temik, the standard at-planting insecticide in North Carolina, was used by survey respondents on 85% of their cotton acreage in 1992 (Fig. 2). Temik provides extended thrips management, earlier maturity of the cotton plant, and, at times, higher yields than other insecticides applied during planting. Growers used the organophosphate insecticides Thimet and Di-Syston on approximately 7% and 2% of their cotton acreage, respectively. The current product label for Command herbicide requires the use of Thimet or Di-Syston as a safening agent to prevent herbicide-induced seedling phytotoxicity. If the 1993 product label for Command is retained, some increase in the use of these two insecticides is expected in the future.

Figure 2

Fig. 2. Insecticides applied at planting to manage thrips. Bars indicate the percentage of acres treated.

Limited use of foliar insecticides for aphid and thrips management prior to first bloom was reported by cotton growers responding to the survey (Fig. 3). These treatments were mostly directed against thrips. Orthene, which is recommended for thrips but not aphid management in North Carolina (Bacheler et al. 1992), was applied to approximately 16% of the acreage. Cygon was used on about 5% of the acreage to manage cotton aphids during this period. Aphids are seldom abundant in pre-bloom cotton in North Carolina. Furthermore, growers are advised against treating for aphids before cotton opens due to the availability of predators, parasites and fungi that limit aphid populations and because of the presence of aphid populations resistant to organophosphate insecticides (Bacheler 1993).

Figure 3

Fig. 3. Foliar insecticides applied to manage aphids and thrips. Bars indicate the percentage of acres treated prior to first bloom (dark) and from first bloom through harvest (hatched); numbers following bars are mean numbers of applications per treated acre.

Survey respondents also relied very little on insecticides to manage cotton aphids from first bloom through harvest. Orthene and Capture were each used by growers on only 1% of the acreage, while Cygon and Bidrin were each applied to less than 1% of the acreage. These results indicate grower recognition of the impact of predators, parasites and fungi on aphid populations.

Bollworms and European corn borers. North Carolina cotton growers almost exclusively utilize pyrethroid insecticides from mid-July through boll opening for the management of the major generations of bollworms and European corn borers. In North Carolina where resistance of these insects to the pyrethroids has not been discovered, pyrethroids are also the predominant insecticides applied from June through the first week in July for the management of early (second) generation bollworms and tobacco budworms. Baythroid, Karate, and to a lesser extent, Ammo, Scout X-tra and Asana XL were pyrethroid insecticides used by survey respondents to manage both the early (Fig. 4) and major (Fig. 5) generations of bollworms, tobacco budworms and European corn borers in their cotton. The carbamate insecticide Larvin was applied to a small percentage of the cotton acreage to manage these insects.

Figure 4

Fig. 4. Insecticides applied from June through the first week in July to manage early generations of bollworms or tobacco budworms. Bars indicate the percentage of acres treated; numbers following bars are mean numbers of applications per treated acre.


Figure 5

Fig. 5. Insecticides applied from mid-July through boll opening to manage major generations of bollworms and European corn borers. Bars indicate the percentage of acres treated; numbers following bars are mean numbers of applications per treated acre.

According to survey respondents, 48% of their cotton acreage was treated with pyrethroid insecticides for early-season bollworms and tobacco budworms. However, the proportion of North Carolina's 1992 cotton acreage treated for the early generation of these insects was probably closer to 5% (Bacheler 1993). It is likely that some of the pyrethroid insecticide applications reported by growers for early generation bollworms and tobacco budworms were actually applied to manage the major generations of bollworms and European corn borers. This seems more apparent because survey respondents reported only about 2 applications of the pyrethroid insecticides to those acres treated for the major bollworm and European corn borer generations. Cotton growers in the state generally made 3 applications of pyrethroid insecticide to manage the major generations of these insects in 1992.

Secondary pests. Pyrethroids were also the most frequently reported insecticides for the management of secondary pests such as beet and fall armyworms, cabbage and soybean loopers, stink bugs, and spider mites (Fig. 6). The use of the carbamate Larvin and the organophosphate insecticide Curacron by growers was probably due to the presence of fall armyworms in a number of cotton fields in 1992. The fall armyworm is an occasional pest of cotton in North Carolina, primarily in the southern counties.

Figure 6

Fig. 6. Insecticides applied to manage spider mites, beet and fall armyworms, cabbage and soybean loopers, and stink bugs. Bars indicate the percentage of acres treated; numbers following bars are mean numbers of applications per treated acre.

Nonchemical Pest Management Practices. Cotton growers were asked if they, family members, employees, and/or professional scouts scouted their cotton crop in 1992 for insects, weeds or diseases. Approximately 54% of the growers surveyed reported that they or a family member scouted their cotton crop. Five percent claimed that an employee scouted their crop. Professional scouts or consultants provided this service for 50% of the growers, according to survey results. Only 2% of growers did not have their cotton scouted in 1992. Fifty-seven percent of survey respondents reported that they rotated fields planted with cotton as a means of pest management, while 35% planted resistant varieties of cotton. Light traps were used by 26% of respondents to monitor insects in their fields.

Fall Survey of Boll Damage. Of the yield loss to insects in North Carolina, a large percentage is due to late season boll damage from caterpillars. Therefore, a statewide survey of boll damage by bollworms, European corn borers and fall armyworms has been conducted annually in the fall since 1985. In 1992, 12 randomly-selected cotton fields in each of the 21 largest cotton- producing counties in the state were surveyed for boll damage by insects. Results from 1992 fall boll damage survey are included in Fig. 7. Boll damage from bollworms, European corn borers and stink bugs in 1992 was less than average; however, boll damage by fall armyworms in 1992 was above average for the state (Bacheler 1993). Fall armyworms reached economic levels in cotton fields in several North Carolina counties in 1992.

Figure 7

Fig. 7. Late-season boll damage by bollworms (BW), European corn borers (ECB), fall armyworms (FAW), and stink bugs (SB) in North Carolina. Dark bars indicate the percentage of bolls damaged in 1992; hatched bars indicate the mean percentage of bolls damaged from 1985-1993.


Literature Cited

Bacheler, J. S. 1993. Insect management on cotton. In 1993 Cotton Information. Publication AG-417. North Carolina Cooperative Extension Service, Raleigh, NC. 145 pp.

Bacheler, J. S., J. R. Bradley, Jr., and J. W. Van Duyn. 1992. Insect Control on Cotton. In T. W. Knecht, ed. 1992 North Carolina Agricultural Chemicals Manual. College of Agriculture and Life Sciences, North Carolina State University, Raleigh, NC. 355 pp.

Christenson, J. A. 1975. A procedure for conducting mail surveys with the general public. J. Community Development Society 6(1): 135-146.

Dillman, D. A. 1978. Mail and Telephone Surveys: The Total Design Method. John Wiley and Sons, New York. 325 pp.

Watson, D. D., ed. 1993. 1993 North Carolina Agricultural Statistics. Publication No. 176. Agricultural Statistics Division, North Carolina Department of Agriculture, Raleigh, NC. 81 pp.


Acknowledgments

We thank the following county extension directors and agents that participated in the survey of cotton growers: A. Ray Harris (Carteret County), J. Michael Williams (Chowan County), Michael W. Shaw (Columbus County), Curtis D. Fountain (Duplin County), R. Douglas Phillips (Halifax County), Byron L. Simonds (Hertford County), Eric V. Spaulding (Johnston County), Alan A. Harper, Jr. (Lenoir County), Mark D. Hucks (Nash County), Daniel Shaw (Onslow County), Richard F. May (Pamlico County), Lewis W. Smith, Jr. (Perquimans County), Benjamin F. McCallum, Jr. (Richmond County), L. Everett Davis (Robeson County), William C. Ellers (Sampson County), David E. Morrison (Scotland County), Richard M. Dowless (Union County) and Connie H. Jernigan (Wilson County). Appreciation is also extended to the North Carolina Department of Agriculture for generously providing mailing lists of cotton growers. Finally, Anne Henderson and Rebecca Osborne are acknowledged for the preparation of survey materials and data entry. This research was supported by the National Agricultural Pesticide Impact Assessment Program, Extension Service, United States Department of Agriculture under project 92-EPIX-1-0071.


Recommendations for the use of chemicals are included in this publication as a convenience to the reader. The use of brand names and any mention or listing of commercial products or services in this publication does not imply endorsement by the North Carolina Cooperative Extension Service nor discrimination against similar products or services not mentioned. Individuals who use chemicals are responsible for ensuring that the intended use complies with current regulations and conforms to the product label. Be sure to obtain current information about usage and examine a current product label before applying any chemical. For assistance, contact an agent of the North Carolina Cooperative Extension Service in your county.




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Web page last modified on August 14, 1996 by Stephen J. Toth, Jr.