Download Presentation

SCA Sampling Protocol
Results: 2016
Tom A. Royer
Oklahoma State University
Sorghum – Sugarcane Aphid
Research Exchange Meeting
Dallas, TX
January 3 – 4, 2017
Introduction
• Goals:
– Develop, validate and
demonstrate a user-friendly,
dynamic sampling tool based on
seasonal and spatial distribution
patterns and linked to researchbased economic thresholds for
sugarcane aphid in grain sorghum
Materials & Methods
• One sampling universe for every 80 acres
– a field of 160 acres could be made into two fields
• 48 of 54 samples per field taken from 2 fully expanded
leaves, one on lower 1/3, and one upper 1/3 of plant
• 6 plants were randomly selected for whole plant counts
• Design allows for analysis of variation within and between
plants, within and between cells, between fields, and
between states
• Fields classified into five growth stages
–
–
–
–
–
Vegetative (01)
Boot (02)
Flowering (03)
Milk (04)
Soft Dough to Maturity (05)
• For data purposes use the closest of the five stages listed
when collecting plant measure data
Materials & Methods
Data Slides
• A nested ANOVA was conducted on
data from125 fields, representing
6750 samples from TX and OK
(fields from other states have not
been included yet)
Key Learnings
• Most of the variation in sampling is
captured within plant samples or between
the two sets of within cell samples
• Sampling for SCA needs to be modified
based on location
– OK and North Texas distribution patterns
saw no substantial difference in variation;
data suggests that there is less need to
consider edge when sampling
– South Texas showed evidence of a slight
edge effect due to a higher % of accounted
variance in the “column” category when
compared to N Texas and Oklahoma.
Next Steps
• Continued field sampling for increased
robustness of data and for independent
validation of sampling protocol
• Evaluation of aphids counts on leaves
within plant for most efficient estimation of
aphid density
Collaborators
•
•
•
•
•
•
•
•
•
•
•
•
Jessica Lindenmayer, Oklahoma State University***
Kristopher L. Giles, Oklahoma State University
N.C. Elliott, USDA-ARS
Ali Zarrabi, Oklahoma State University
Mark Payton, Oklahoma State University
Allan Knutson, Texas A&M Agrilife
Xandra Morris, Texas A&M Agrilife
Robert Bowling, Texas A&M Agrilife
Michael Brewer, Texas A&M Agrilife
Nick Seiter, University of Arkansas
Sebe Brown, Louisiana State University
Brian McCornack, Kansas State University
Discussion