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2002 - 2003 CUIPM Grants -
Final Reports
Developing a Cabbage Scouting Program for Limited Resource Farmers
Roger L. Francis
Clemson University Extension Service
259 Meeting St
Charleston, SC 29406
Cooperator: Dr. B. Merle Shepard
Coastal Research and Education Center
2000 Hwy. 17
Charleston, SC. 29414
Problem Description: Cabbage production is a major cash enterprise among small limited resource vegetable growers in Charleston and surrounding counties. The major insects attacking the crop are diamondback moth (DBM), imported cabbageworm (ICW) and cabbage loopers (CL). To produce a marketable head of cabbage, growers make routine spray applications to the crop. As a result of this practice, evidence of DBM resistance to some chemicals has been reported in the county. Chemicals such ASANA, Lanate, Pounce, Ambush, Monitor, and Bacillius thuringiensis (Bt) are widely used in the production of this crop.
Routine spray applications have negative impacts on farm income, the environment, and beneficial non-target insects. This practice increases the risk of pests developing resistance, therefore, reducing the effectiveness of selected chemicals used in the crop production system. Growers sometimes unknowingly expose their family members to health risks from this practice. Stricter government regulation of pesticide use, availability and increase costs have also resulted.
Methods: In the final year of the project, five (3 IPM plots, 2 grower-managed plots) on-farm plots were established on four farms in Charleston County. Two farms had IPM and grower-managed plots, the others had only grower-managed plots. The plots ranged in size from .5 acres to 3 acres in size.
Land preparation and other cultural practices were carried out by the growers. All plots were planted with cabbage transplants using Clemson Extension recommendations. The plots were established during late winter and early spring of both 2002 and 2003. Because of heavy and continuous rainfall, all the plots had to be replanted in 2003. Scouting of the IPM plots started in March 2002 and April 2003. Scouting of the fields continued up to harvest. The late start in scouting the fields in 2003 was due mainly to a combination of replanting, heavy rains and field conditions.
To encourage scouting by growers, an efficient, easy-to-use field scouting plan that incorporate all three species of caterpillar, diamondback moth (DBM), cabbage looper (CL) and imported cabbage worm (ICW) into one plan was used. Each plot was sampled using the sequential sample table developed by Shepard and Grotheson (1984).
The sampling pattern followed a zig zag route across the field. The objective was to ensure that the entire plot was covered. A total of 10 plants were sampled two times per week in the IPM plots. Each plant was randomly selected and checked for damage and live caterpillars (irrespective of species). Plants with damage and a live caterpillar were recorded as positive, plants with or without damage and no caterpillar were recorded as negative. One of the grower-managed plots was scouted weekly. The objective was to observe if there was any relationship between insect population/damage and the growers' spray decision. Results of the weekly scouting reports were not made available to the grower.
Because of the low tolerance for insect damage on the crop, an action threshold of three damaged plants with caterpillar was used. The decision to spray the IPM plots was made when three positive plants were recorded; alternatively, no spray decision was made when less than three positives were found. The IPM plots were sprayed with a bio-insecticide when required. The growers made the decision on what they would spray with.
Summary: This is the final report of a two year non-replicated on-farm IPM demonstration. The demonstrations have shown that small-scale growers can produce marketable cabbage using IPM practices. The sequential sampling technique used was precise, simply and easy-to-use. IPM practices reduced the number of spray applications needed to produce marketable cabbage compared to regular grower practice. In 2002 and 2003 the reduction in spray applications made to the IPM plots was 20% and 40% respectively (Tables 1 & 2). Spray applications made to the IPM plots were based entirely on the scouting reports. Over the two years duration of the project, the average number spray applications made to the IPM plots was three (3) compared to five (5) spray applications in the grower-managed plots. This represents a 20% reduction in spray applications overall. Growers have started to include bio-insecticides (Bt) into their regular spraying program in the production of the crop.
By scouting cabbage fields regularly, growers can minimize damage by targeting the early stages of the pest larvae development with their spray application. The advantages to growers are better insect control, lower dosage of pesticides and reduce cost. Additionally, growers can better manage potential disease problems in their fields.
Table 1: Sampling for Cabbage Caterpillars in IPM Cabbage Plots 2002
| Farm |
Start-up sampling date |
End sampling date |
No. of Field Visits |
No. of treat decisions in IPM |
*Avg. No. of grower sprays |
% reduction in sprays |
| Freeman Farm |
3-6-02 |
5-28-02 |
22 |
3 |
5 |
40 |
| Fields Farm |
3-6-02 |
5-28-02 |
22 |
4 |
5 |
20 |
| Average |
|
|
|
4 |
5 |
20 |
Table 2: Sequential Sampling for Caterpillars in IPM Cabbage Plot 2003
| Farm |
Start-up sampling date |
End sampling date |
No. of field visits |
No. of treat decision in IPM plot |
*Avg. no. of grower sprays |
% reduction in sprays |
| Freeman Farm |
4-3-03 |
6-2-03 |
17 |
2 |
4 |
50 |
| Fields Farm |
|
|
17 |
4 |
5 |
20 |
| Average |
|
|
|
3 |
5 |
40 |
* Based on routine grower practice
Impact: As a result of the demonstrations, some growers have reduced the application of some of the older and environmentally harsh pesticides that they generally use in the production of cabbage. They have replaced the application of these chemicals with Bt. While they are only making one application of Bt, at present, this represents a positive change in attitude and perception towards the adoption of IPM practices. Another major impact of the project, while negligible, is that a few growers have made attempts to adopt scouting their fields using the sampling program as a regular practice.
Extension educational activities such as field days and printing of a simple and user-friendly IPM guide to promote scouting and other IPM practices are being planned. The field day will be held at the CREC in Charleston. Field day activities will emphasis scouting procedures, identification of beneficial and harmful insects. The hand-on approach will serve as a vehicle to encourage widescale adoption of IPM among small scale cabbage growers in the Charleston and surrounding counties.
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Questions or comments:
Amy Nichols
Associate Coordinator
IPM and
Sustainable Agriculture
Programs
Contact
Dr. Geoffrey Zehnder
Professor of Entomology, Soils & Plant Sciences
IPM and
Sustainable Agriculture
Programs
114 Long Hall, Box 340315
Clemson, SC 29634-0315
864 - 656 - 6644
Contact
Last revised:
8/4/2006 |
Clemson University Cooperative Extension Service offers its programs to people of all ages, regardless of race, color, sex, religion, national origin, disability, political beliefs, sexual orientation, marital or family status and is an equal opportunity employer. |
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