1. Influences of Planting Population on Sugarcane Aphid (Melanaphis sacchari) in Grain Sorghum (Sorghum bicolor)
Brittany Lipsey
Mississippi State University
Sorghum – Sugarcane Aphid
Research Exchange Meeting
Dallas, TX
January 3 – 4, 2017

2. Collaborators Name Affiliation Trial Location Plant Date Spray
Angus Catchot
Mississippi State University
Starkville, MS
Jeff Gore
Stoneville, MS

3. Objective
Determine the influence of plant population and insecticide treatment on sugarcane aphid densities in grain sorghum

5. Materials & Methods
RCB design with a factorial arrangement of treatments replicated 4 times in 2015 and 2016.
Factor A= Planting Population
Factor B= Treated Plots vs. Untreated Control Plots
Treated plots were treated with seed treatment and with foliar insecticide on current threshold.
The data were analyzed with regression analysis and analysis of covariance was used to compare slopes.
Aphid counts were taken weekly during infestation by examining 15 flag leaves and 15 bottom leaves in each plot and estimating the total number of aphids on each leaf.
The center two rows were harvest and adjusted to 13% moisture.

6. SCA in Treated Plots in 2015 and 2016

7. Total SCA in Treated Plots 2015 and 2016

8. SCA in Untreated Plots in 2015 and 2016

9. Total SCA in Untreated Plots 2015 and 2016

10. Yield 2015

11. Yield 2016

12. Key Learnings
We observed a NEGATIVE correlation between aphid numbers and population effect. As population increased aphid populations decreased.
Bottom leaves consistently had HIGHER aphid numbers than top leaves.
Yield in 2015 positively correlated with population. As we observed an increase in population, we also observed an increase in yield. In 2016, we observed no correlation between plant population and yield but a drastic difference in yield due to seed treatment.
We think that the small plot size diminished some of the population effects that would have occurred in field settings (large plot).
B. C. Thrash