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Crop watch

By Staff | Sep 13, 2019

The sun is setting twenty minutes earlier each week as we move later into the growing season. This year that will be worth keeping track of as about one third of the corn crop was planted in June. Whether or not that portion makes it to black layer before a freeze hits is the multibillion dollar question for Midwest corn growers.

In driving through Iowa and a few surrounding states the crops are slowly taking on the fall-like look. One can see the patchwork appearance of the bean fields, some completely yellowed while others are dark green yet. It is always noticeable at first where the color change is just barely visible but increases as the days pass. I was in Missouri twice last week and in the Kansas City trip on Saturday most of the corn was a sunny bright yellow or yellowish brown. With their additional GDUs the plants likely died a normal death after reaching a normal maturity.

So the Farm Progress Show is history and Husker Harvest Days out in Nebraska take place the middle of this week. I never heard how the FPS crowd was or if there was one item, event, or program roll out that captured the attention of the crowd. Locally the small plot showings are continuing.

Field scouting

In walking fields it is apparent the corn plants in the fields have slowed down in development with the cooler temps. With last week’s cool highs and this past weekend with low to mid 40 F temps up in Minnestoa and Wisconsin, the cold air is not far away. The first planted corn from mid April to early May is nearing black layer and seems to have good kernel depth. It looks to have very good yield potential.

The middle group is good but has more tipback as moisture was not as plentiful during the late blister stage. The early harvest reports and field estimates by commodity people are verifying how the USDA reports are overly optimistic in their yield projection.

The June planted acres vary in appearance and yield potential based on whether they were planted to collect on crop insurance, so inputs were minimized, or if they were well tended and received micronutrients and sidedressed nitrogen.

The value of having access to high clearance equipment to do the sidedressing was great. The 30 to 50 days of saturated soils led to lots of N subject to denitrification.


The bean plants in northern Iowa seem to be much taller than plants in central and southern Iowa. They appear to be as tall as in past years, but lack the very heavy podding and terminal clusters as seen in other years. How much of that might relate to the very late flowering seen in fields where no flowers had formed when they were in the V6 to V8 growth stages?

The yellowing seen now is continuing to be caused by either senescence, low K uptake, low fertility levels or SDS infections. The SDS likely should have been a larger problem, but the worst fields likely were those that ended up being PP. There may be a few more product choices to use in minimizing the yield effect of SDS with some being plant extracts, some biological, a few mineral related and some chemical in nature.

Reports from across the western bean belt about finding gall midget are still coming in. At last count the number of infected counties documented this year versus 2018 have increased by about 50 percent. This may climb as combines move into the fields, yet could stay low as a portion of the plants stayed so small they may not have lodged as much as if they had grown taller and were holding up more weight.

In rating diseases in bean fields the primary ones that are present now are Septoria brown spot, Frogeye leaf spot (Cerspora sojina), Cercospora leaf blight which turns the leaf a leathery brown, SDS, and Downey Mildew. The incidence levels are high but severity ratings remain low.


The early season predictions for this being the year of the pigweeds or waterhemp proved correct. The taller ones have risen above the crop canopy in many fields. With the plants’ ability to form huge numbers of seed and to germinate through early August, gaining full season control is difficult. Now is the time to scout your different fields, take notes on escapes to rate each field, and begin to formulate your weed control plans for 2020.

I have not seen Bob Hartzler’s notes of his usual Labor Day trip to the counties where Palmer Amaranth was first found. I saw those plants at heavy levels in fields just west of Omaha last fall. Their seeds likely spread far with the floods in March to many areas down river. Several counties up near Redwood Falls, Minnesota have documented that weed to our north. With its ability to spread and become a management problem, everyone needs to stay vigilant and use every means possible to control it.

Disease issues in corn

Now with more corn nearing maturity and mineral levels declining due the droughty soils, the leaf disease pressure appears to be increasing. That can be seen in central and north central Iowa now with corn plants beginning to collapse in areas.

With wetter conditions again and more dews Southern Rust is appearing in more fields, especially were humidity levels are higher. It likes hot and moist weather.

On schedule with the development stages of the plants is tar spot with it being found in Illinois, Indiana, Wisconsin and a few more states. It should not be a factor on yield where the corn was planted on time. In later planted fields where most of the grain fill has to be accomplished growers may be forced to control it.

Cover crop plantings

There are growers who have been seeing benefits from the planting of cover crops and hope to get their acres planted this fall. There was a rep from the Montag Company at a summer field day who was showing the finished designs for a tank and Gandy Box style spreading equipment as a unit that could be mounted on a Hagie sprayer to spread seed in a standing crop prior to harvest. The cost on it was such that it would be attractive for a person already owning a Hagie to do enough custom work and could justify purchasing one. The time gained meant the cover crop seed was more likely to germinate and put on growth before the fall freeze arrived.

Bob Streit is an independent crop consultant and columnist for Farm News. He can be reached at (515) 709-0143 or www.CentralIowaAg.com

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