Brown Ring On A Few Stems

[showmegreen]

Ants do that roun here ta sunflowers. Probly grabbin starches an tha sugary like fer their molds a fungus they eat off. Sugar water (flat mtn dew) an borax work great.

 

[TOTreesDotCom]

I know this is a five year old post, but I wanted to add my thoughts on this issue.

This is the second year I’ve had issues with the brown rings, and as OP stated, it’s definitely ants doing it. I’ve seen them clustered around the stem biting or drinking. I haven’t had stems die, but sometimes above the ring I do get root primordia beginning to develop above the ring (white bumps in OP pic).

My theory is it’s a harvesting behaviour. The ants want resin and sugar from the plants, so they disable the plant in a way that makes it stress and flower faster, and also make it fall apart so it’s easier to harvest.

I find that the stems on mine don’t die off, but in fall when the wind picks up and the nugs gain weight, they snap off. Very disappointing when it’s your top cola and it still has 2-3 weeks to go...

 

[TOTreesDotCom]

Update: saw the real culprits today: Buffalo Tree Hoppers. They are camouflage and rotate around the stem and jump when they see you, leaving just the ants behind. I’ve seen three now on the rings, with ants feeding on their honeydew.