another soybean question

[bueller]

First time for me planting beans. Is it normal for the two bottom unifoliate leaves to turn yellow? White flowers are just beginning to appear on some of the plants.

 

[wiscwhip]

Did you inoculate your seed before planting? If not, they need N.

 

[bueller]

I did not inoculate. The rest of the leaves are a nice dark green even with the hit and dry weather lately. Only the bottom two unifoliate leaves are turning yellow.

 

[bueller]

I did apply a decent amount of N at time of planting.

 

[wiscwhip]

Hmmm...maybe deficient in potassium (K)? I would think that would show up on more than just the bottom set of leaves though? Or maybe just that dry beach your plotting on? Could it just be stress from lack of water or have you had sufficient rain? Our beans never got anywhere near a flowering stage to see any of those symptoms because the deer ate the whole 1/2 acre to the dirt when they would get between 4"-8" tall.

Any small brown spots on the leaves?

 

[bueller]

Didn't notice any brown spots. Field didn't come in thick enough to get anywhere close to forming a canopy so they've been baking the last couple weeks. Rain gauge had .10 in it for the last two weeks. I'm sure a little bit more fell and evaporated before I got back up there but I know we've been dry as I watch the reports pretty darn close throughout the growing season.

 

[bueller]

So I guess it's not "normal" for the two lowest leaves to be going yellow at this point?

 

[wiscwhip]

No, not "normal" until the pods start to mature and all the leaves turn yellow and fall off....in September. It could very well be the start of some heat/water stress, which there isn't much you can do to remedy. Next time you are out there, take a small shovel or posthole digger to a few spots in between some healthier plants and see how far down it is before you reach moist dirt. I'm betting if you haven't had any recent rainfall, it will be dry for the first 4" to 6" at least. Those hot, dry, windy days we had over the last couple weeks will turn that soil to dust in short order if the sun hits the ground at all.

 

[Nova]

I see it every year on my beans, both at home and at the farm. I guess I always thought it was normal. I just noticed yesterday on one of my plots at home there were a few with little purple flowers on them and the bottom leaves were yellowing. They are eagle beans hence the purple flowers, but I have also noticed it on my ag beans. I will check the farm field next to my house tonight. He has beans in there and see if I see the lower leaves yellowing.

 

[bueller]

No, not "normal" until the pods start to mature and all the leaves turn yellow and fall off....in September. It could very well be the start of some heat/water stress, which there isn't much you can do to remedy. Next time you are out there, take a small shovel or posthole digger to a few spots in between some healthier plants and see how far down it is before you reach moist dirt. I'm betting if you haven't had any recent rainfall, it will be dry for the first 4" to 6" at least. Those hot, dry, windy days we had over the last couple weeks will turn that soil to dust in short order if the sun hits the ground at all.

Hopefully next time I'm there it will have rained a bunch so I can rule out moisture

 

[Barndog56]

I did apply a decent amount of N at time of planting.

I know it's a little late for this advice, and most have probably not heard of this, but you should apply 1 pound of sulfur for every 10 pounds of nitrogen. The soil bacteria that processes nitrogen into peptides for the plant to uptake, uses sulfur to do it. When sulfur is lacking the nitrogen goes unused until it finally leaches away.

Farms without irrigation around here are having serious problems. Beans across the road from me all have their leaves upside down, and corn leaves are all curled up, right when it's starting to make tassels. Doesn't seem to be any significant rainfall in the 10 day either. So that could very well be your problem too.

 

[Tree Spud]

Hopefully next time I'm there it will have rained a bunch so I can rule out moisture

Time to start broadcasting the turnip & clover seed ... hopefully the nighttime dew will give them a head start ...

 

[Bill]

I get yellow leaves all the time in my beans. Never thought anything of it. I guess if I was farming for 40 bushels an acre I'd be more into finding out why. I wouldn't sweat it for deer unless the flowers start falling off.

 

[Nova]

First pic is my eagle s beans yellowing at the base, the other two are the ag beans in the farm field next to me. I do see brown dots on the leaves, what is that tell me?

 

[wiscwhip]

Most likely septoria leaf spot...shouldn't affect a deer plot, only farmers looking for max yields, but it would explain the lower leaves turning yellow, that is why I asked.


https://fyi.uwex.edu/fieldcroppathology/soybean_pests_diseases/septoria_brown_spot_soybean/

 

[S.T.Fanatic]

That was my thought when I saw the ag beans. I wonder if the yellowing lower leaves on the Eagles is the same thing or is it due to a lac of sunlight as the beans grow tall and canopy?

 

[Nova]

That was my thought when I saw the ag beans. I wonder if the yellowing lower leaves on the Eagles is the same thing or is it due to a lac of sunlight as the beans grow tall and canopy?

I doubt it is the lack of sunlight, the eagle beans pic was taken of the outside row on the east side of the plot that borders a mowed trail. That pic was taken at 4pm last night and they were still getting sun.

 

[S.T.Fanatic]

I know it's a little late for this advice, and most have probably not heard of this, but you should apply 1 pound of sulfur for every 10 pounds of nitrogen. The soil bacteria that processes nitrogen into peptides for the plant to uptake, uses sulfur to do it. When sulfur is lacking the nitrogen goes unused until it finally leaches away.

Farms without irrigation around here are having serious problems. Beans across the road from me all have their leaves upside down, and corn leaves are all curled up, right when it's starting to make tassels. Doesn't seem to be any significant rainfall in the 10 day either. So that could very well be your problem too.

This is partly the reason I use a half and half ratio of urea and AMS.

 

[S.T.Fanatic]

I doubt it is the lack of sunlight, the eagle beans pic was taken of the outside row on the east side of the plot that borders a mowed trail. That pic was taken at 4pm last night and they were still getting sun.

Leaf spot is just another reason to switch to no till agriculture. Now if I only had the money to blow on a good drill.

 

[Nova]

Most likely septoria leaf spot...shouldn't affect a deer plot, only farmers looking for max yields, but it would explain the lower leaves turning yellow, that is why I asked.


https://fyi.uwex.edu/fieldcroppathology/soybean_pests_diseases/septoria_brown_spot_soybean/

Thanks for the link Wiscwhip! Warm wet weather promotes it and that is exact;y what it has been this year. Very likely that is the issue with the ag beans as they look just like the pics in the link, but the eagle beans look different to me.