Controlling aphids remains a judgment call, says University of Georgia Extension entomologist Dr. Phillip Roberts, who has completed lots of research on cotton aphids and has not seen a consistent yield response from controlling them.
Cotton aphids are showing up in fields now. We're (in south Georgia) mostly seeing 'hot spots.' In these places, we may see honeydew, sticky, shiny material, yellowing in the terminal.
Roberts says one of the most important things we can do is look for a naturally occurring fungus that cause aphid populations to crash. We look for gray, fuzzy aphid cadavers. As aphids build, the fungus multiplies, and aphids crash. The crash happens fast and kills all aphids within a week or so.
A few points to consider when making the decision on spraying for aphids is
- If terminal has turned yellow.
- If the whole field has aphids (instead of just hot spot).
We will also see lots of beneficial insects from lady beetles to wasps while aphids are present. Lady beetles are predators, and their larvae eat aphids.
(Sawyer is University of Georgia Extension agent in Thomas County, Ga.)