Sorghum Headworm Sequential Sampling System

1. Sorghum Headworm Sequential Sampling System Tom A. Royer Department of Entomology & Plant Pathology Oklahoma State University

2. Development of Headworm Sampling System • Data on Economic and Treatment thresholds collected from Texas, Oklahoma, and Kansas (Elliott et al. 2012) • Objectives: • Create a simple, dynamic, economically accurate sampling strategy for sorghum headworms • Develop an educational tool with information on headworm identification, and other sorghum pests. • Develop a flexible system that could be expanded as additional information became available and/or interface with real-time platform (such as I-Wheat). Oklahoma State University

3. The Product • A computer program located at http://entoplp.okstate.edu/shwweb/index.htm • It has several elements: • Information on sorghum headworm • A calculator for determining economic thresholds for headworm infestations • Sequential sampling forms • Sampling instructions • Information on other sorghum pests Oklahoma State University

4. What Does the Headworm Decision Support System Provide? • It allows a producer to play the “what If” game with pesticide costs, market values Oklahoma State University

5. What Does the Headworm Decision Support System Provide? • It has a full complement of treatment threshold forms that can be printed off to serve as a permanent record of the sampling results Oklahoma State University

6. Assumptions: The Scout Needs to: • Estimate sorghum plant populations • Estimate composition of headworm sizes (Large, Medium, Mixed) • Mostly large headworms > ½ inch cause significant damage • Mostly medium headworms ¼ to ½ inches will also cause damage (less so, due to field mortality) • Small headworms < ¼ inches are not counted because many will die Oklahoma State University

7. Oklahoma State University

8. What You Need to Know • Plant Density • Number of sorghum heads per acre • Number of sorghum heads per length of row spacing • Pounds of seed planted per acre • (assume that a pound of seed per acre results in 35,000 heads per acre • None of the Above • (assume that 1 inch of rainfall results in 1100 heads per acre. Inches of rainfall is determined by clicking your location on the map. • (3 or 4 won’t give you as accurate an estimate) Oklahoma State University

9. What You Need to Know • Value of crop ($ per hundredweight) • Control Cost ($ per acre) Oklahoma State University

10. What You Need to Know Directions Sampling Technique • Walk 15-20 feet into field • Grasp and bend head into bucket and shake vigorously • Walk 30 paces in row to next sample, repeat 2 • Walk 30 paces to next sample, repeat 2 (STOP 1) • Count medium (1/4 – ½ inches) and large > ½ inches) caterpillars, and determine whether most are Medium, Large or a Mixture (ca. 50/50). Oklahoma State University

11. What You Need to Know Directions Sampling Form • Sample 3 more heads, combine count from first three heads with new count, mark total in box (STOP 2). Determine if you need to treat, not treat, or sample 3 more heads. • If you need to sample 3 more heads, move over 25 rows, and sample 3 heads. • Repeat 1 (STOP 3). • Repeat 1, and move over 25 rows AFTER you sample 6 heads in each row. Oklahoma State University

12. What You Need to Know Directions Sampling Form • If you sample at 16 stops and still can’t make a decision, return in 3 days and resample the field. Oklahoma State University

13. Data on time to decision. 10 fields, 16 stops, no decision made: 10 fields, no treatment after 3 stops, 9 samples Average time per stop: • Average time: 19 minutes 37 seconds • Average time: 3 minutes 4 seconds • 1 minute 12 seconds Oklahoma State University

14. Next?. • An Application for Smart Phone use in field. Oklahoma State University

15. Thanks! Oklahoma State University