Bob’s Bits July 2nd, 2026 | June Recap

June Recap

Whew, we made it through a couple months of this crop and I feel things are looking real good.  We have great stands, haven’t had washouts, or leaching of N for the corn, and the weeds are pretty well under control.  We have been doing some later spraying in beans to clean up some late waterhemp escapes, but other than that, I’m optimistic for good crop yields.

Weather Status

I want to give a recap of where we are for the season weather-wise.  Here are a couple maps showing the total rainfall and temperature departures for May and June.  As you can see, we are about tracking normal on overall temperature, although later June was a little cooler, but we are tracking lower on overall precipitation.  I know there are areas that wouldn’t agree with the precipitation as there have been isolated areas with heavy rainfall events.

Grand Growth Stage

The average to cooler weather we had in June has been great for reducing stress on the crops.  Corn develops the ear size mainly during the V5-V8 leaf stages.  We are now into the “grand growth” stage of corn, where we can almost watch corn grow daily.  There are a lot of nutrients being taken up into the corn plant, and if we have compacted, or saturated soils, the roots won’t be able to take up what they need.  The plant is storing the nutrients that will later be relocated into the developing ear.  The following chart from Nachurs shows the percentage of nutrients taken up during the various stages of growth.  A couple things to note are the Boron and Zinc uptake during this time.  Almost 1/3 of the total usage is taken up during the grand growth stage, and then it drops off to almost nothing until the mid reproductive stage again.

We focus on getting Zinc and Boron out ahead of these uptake times, so the nutrients are available in a usable form.  That is why we focus on some foliars at V5-V10, and again at tassel time with the fungicides.  Zinc is important for cell division, and Boron is called the “Sugar Mover”, it basically works to keep the veins open which helps move the photosynthate material within the plant.

Disease Outlook

With the corn crop looking good now, I have been getting some calls about looking ahead to fungicides.  There is concern about the major diseases, Tar Spot and Southern Rust, and how to manage them if they show up.  There is a website, https://cropprotectionnetwork.org/maps/tar-spot-of-corn, that has up to date maps of counties reporting Tar Spot presence, and one for Southern Rust, https://cropprotectionnetwork.org/maps/southern-corn-rust.  As of today, Tar Spot has been confirmed in Chickasaw County, but the nearest positive Southern Rust is way down in Texas.  Remember, Tar Spot likes leaf wetness, but moderate to cooler temperatures.  Southern Rust is a more tropical disease so it needs moist and warmer temperatures.  The weather going forward will determine where we end up on these diseases, along with our normal corn diseases, like Gray Leaf Spot, Northern Corn Leaf Blight, and Eyespot.

I still suggest spraying a premium fungicide at full tassel to protect the corn during its most stressful time, and to be on the front side of disease development, as we cannot grow back any leaf tissue we have lost.  We can only prevent more spread of the disease.  I have also had several farmers asking about how to handle a two-pass fungicide plan if Tar Spot or Southern Rust become as bad as we saw last year, or a few years ago.  In this case, I still recommend spraying a premium fungicide with long lasting residual at full tassel, and evaluate after 2-3 weeks.  If treatment is needed again, we should be fine with a lower tier fungicide or an older generic fungicide to extend the residual further into the grain fill period.

The late April planted corn is about 5-6 leaves away from starting to tassel.  It takes about 50-55 heat units for each new leaf to emerge after V10.  So, with forecasted highs in the 80’s for the next 10 days, we could see tassels starting to emerge in around 10-14 days.

For soybeans, the beans planted in April are fully blossoming.  This is the time to put any preventative products for White Mold out.  Some farmers have used Cobra, Aproach Fungicide, or a new fungicide called Zorina for White Mold at this time.  The objective is to apply when the flowers are present to protect the White Mold fungus from entering the plant as the flower dries up.  We are forecast for a potential high amount of moisture this week, so there could be some risk for White Mold to develop, especially if and when we cool back off to more normal temperatures.

I like to see the soybean rows fully closed by July 4^th, or at least by the time we are fully blossomed.  Soybean leaves need to capture all the sunlight available for plant development.  For this reason, I am a fan of narrower rows, especially in no-till situations that tend to keep the beans on the shorter size.

Here are the total GDU’s we’ve collected compared to average.

Heat Units Accumulated

And Rainfall, this is at New Hampton, which understandably is different for everyone.

RainFall Totals

Please reach out to me if you have any questions or concerns about your crop going forward.  Everyone have a Happy Fourth of July, and Happy 250^th Birthday America!!

Bob Sobolik

641.330.1815