I posted on my Instagram stories a few weeks ago about gall midge after walking into a few of our soybean fields, scraping back the damaged stem, and finding little orange larvae.
Now, keep in mind, I’m not an agronomist and I won’t claim to be. But, I am a farmer who likes to learn. And boy, do I have a lot to learn.
It seems like every time I walk into a field, I find something new to me and am filled with questions.
One ‘new to me’ threat I found this year while scouting was gall midge.
Keep in mind, gall midge hasn’t been a big concern in our area in the past few years. It’s been around, but it hasn’t been something we’ve really had to worry about.
Now, however, it’s looking like it might become a bigger threat.
In this article, I’ll share:
- How we found it/what it looks like in the field
- What to do this year if you find it
- How to prevent it next year
- What impact gall midge can have on yields
How we found it
In any of the fields we found gall midge, it was worse near the edges.
We’d walk in a few rows in from the end rows and, when you’d push back the bean plants, the stems would be weak. Some would snap off near the ground.
Getting closer to where the stem meets the ground, we saw dark discoloration, as you can see in the picture below.
We took a pocket knife and gently scraped on the damaged part of the stem. You don’t have to scrape very deep and, if you catch it at the right time in the gall midge life cycle, you’ll see little orange larvae.
Keep in mind, the life cycle of a gall midge is around 4 weeks. The adult gall midge is a small fly, which then lays eggs near the base of the soybean plant, and the eggs hatch into larvae, which turn orange as they get older and feed on the stems of the plant.
What to do this year if you find it in your field
Unfortunately, once the larvae have entered the plant, there isn’t much you can do to suppress it.
Which, as farmers finding it in our fields, is a very helpless feeling like so many other problems.
Gall midge will eventually kill the plant as it feeds off the stem.
It’s important to get in your fields and assess which ones, if any, have been impacted by gall midge even though you can’t kill them once they’ve entered the stem.
Considering the plants will die early, you’re at risk of them falling over and making harvest much more difficult. If you know which fields have been impacted most, you can better plan which fields to harvest first.
How to prevent it next year
Because research hasn’t been done on gall midge management practices for very long, there aren’t any research-based effective management strategies that have been found to combat the larvae, according to Iowa State.
One thing the Iowa Soybean Association mentions as a potential way to limit gall midge moving into your field is to try to stop the midges through foliar contact insecticide application at the first sight of the adult midges (i.e. the flies) in the first 4-8 weeks after planting.
Sticky traps or emergence cages are recommended to use to monitor for the adult gall midges, but they can be very difficult to identify.
A good starting point would be to do an application on the field edges first but, again, there’s not enough research yet to know what the most effective method is.
What impact can gall midge have on yields?
According to soybeaninfo.com, “Yield loss estimates on a small sample of plants from a heavily damaged field indicate complete yield losses from the field edge up to 100 feet, with about a 20% yield loss 200 and 400 feet from the field edge.”
You might be wondering, why is the Farm Girl Next Door talking about soybean gall midge? What does this have to do with my marketing?
Well, when it comes to marketing, a loss in yield directly relates to a change in your breakeven — your cost of production stays the same but gets allocated across fewer bushels.
Thus, you’ll need a higher cash price to breakeven, which will change your grain marketing plan and target prices.
Moral of the story, never forget how intertwined your yield and your grain marketing plan really are.