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

Oklahoma State University 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 The Product A computer program located at It has several elements: 1. Information on sorghum headworm 2. A calculator for determining economic thresholds for headworm infestations 3. Sequential sampling forms 4. Sampling instructions 5. Information on other sorghum pests

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

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

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

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

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

What You Need to Know Directions 1. Walk feet into field 2. Grasp and bend head into bucket and shake vigorously 3. Walk 30 paces in row to next sample, repeat 2 4. Walk 30 paces to next sample, repeat 2 (STOP 1) 5. Count medium ( 1 / 4 – ½ inches) and large > ½ inches) caterpillars, and determine whether most are Medium, Large or a Mixture (ca. 50/50). Sampling Technique Oklahoma State University

What You Need to Know Directions 1. 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. 2. If you need to sample 3 more heads, move over 25 rows, and sample 3 heads. 3. Repeat 1 (STOP 3). 4. Repeat 1, and move over 25 rows AFTER you sample 6 heads in each row. Sampling Form Oklahoma State University

What You Need to Know Directions 1. If you sample at 16 stops and still can’t make a decision, return in 3 days and resample the field. Sampling Form Oklahoma State University

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

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

Oklahoma State University Thanks!