Early August Observations
By: Mike Toohill, Consulting Agronomist, AgVenture WSC
June was too wet in many areas and/or July was too dry in many areas. So, what are we seeing in the field in early August?
Today we are going to focus on two weather maps. The most concerning colors on the June observed precipitation are the dark reds (8 to 10”) and hot pinks (10 to 15”). The most worrisome colors on the July % of normal precipitation map (as of July 28th) are the reds (less than 25% of normal) and orange (25 to 50% of normal).
Heavy June rains areas and VARIABILTY: Our southern McLean County Illinois farm was one of the “lucky” locations that had over 10” of June rain and corn plant height varies from form 13’ (well drained old hay and pasture ground) to 3’ in the mud holes with plants of all sizes in between. This is common in heavy rain areas around the Midwest. As far as soybeans in heavy June areas, they vary from dead spots to replanted in the holes to stunted survivors to decent beans in well drained areas.
Very dry July impacts: Non-irrigated sand crops are looking tough in dry areas as is corn and soybeans in lighter soil types. The corn edges are also getting burnt in many fields that are located north and east of soybean fields (from hot and dry, south, southwest and west winds).
What if you had a very wet June and a dry July? The low ground looks rough from June moisture and the higher ground looks rough from July hot and dry…
June weather’s main impact on August ear development: In locations with very wet June weather, short, shallow rooted yellow N deficient corn is very common in areas of the field with compromised drainage. Corn planted in mid-May was most impacted (grew in saturated conditions much earlier in its life cycle compared to April and early May planted fields that had a chance to root deeper when it was drier in May). Below left is what the ears look like in the bad spots in most of those fields:
There are also some pollination issues, most common with late emerging and stunted plants.
June and July’s weather’s impact on tip back: Above right is a picture of the tip back that is very common in areas impacted by too much June rain followed by July hot and/or dry. For review tip mainly occurs in the milk and dough stages of corn development. Below are the most common reasons why corn is tipping back in 2026:
Lack of root available moisture.
Lack of nutrient uptake/availability (especially N).
Hot nights (mid 70s plus with multiple consecutive nights at these temperatures). In this situation, corn “focuses” more on plant cooling than kernel keeping and building.
Reduced genetic plant height from June moisture stress keeping the canopy hotter.
Edge effect from HOT SOUTH & WEST winds (usually on the north and east sides of bean fields and large roads).
What if hot and dry weather persists into August? Premature corn plant death can occur. If it happens at full dent, Purdue says to expect a 41% yield reduction. The number is 12% yield loss when corn dies early at 50% milk/starch.
Soybean yield impacts from too much June rain and July dry? While most farmers still consider soybeans to be an August crop, my experiences indicate that earlier planted early to mid-maturities need good July rains (but not too much) to maximize nitrogen mineralization/recycling and maximize pod set and early fill. Most soybean fields in heavy June rain areas with a dry July are slow growing, very hard with reduced nodulization and poor nodule health. Thus, I think the top end has already been taken off in most early planted early to mid-maturities in fields impacted by adverse June and July weather. The later planted and later maturities need have more time. All soybeans need rain ASAP.
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