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Water and temperature affect many crop processes simultaneously ranging from crop growth, development, photosynthesis, respiration, water transpiration, grain fill, and nutrient cycling. The magnitude of high temperature or drought stress depends also on the stage of the crop. Another factor that should be considered is how high minimum temperatures are.

The spotty rain and dry weather saga continues in many parts of the state. The U.S. Drought Monitor has just over 47% of the state as abnormally dry and 16% of the state in a moderate drought.


Source: U.S. Drought Monitor 

The 2017 State Fair Weed Identification Contest will be held on Friday, August 11, from 9:00 AM to 11:30 AM.  Contestants can show up anytime during this period and complete the task at their own pace.  

1) Develops in hot, dry weather conditions. Charcoal rot is a fungal disease that is most severe in years and areas experiencing hot, dry weather. However, this disease can also cause losses when ample moisture is present, making it a hidden threat to yield.

The Twitter accounts @corndisease and @soydisease are a place for farmers agronomists, crop consultants, and specialists to collectively document and track corn and soybean diseases this growing season. To help out with the effort, just take a photo of the crop disease when you’re out scouting fields and then tweet the photo to @corndisease or @soydisease with the name of the disease, and the county and state it’s found in.

While off-target movement of pesticides is not a new problem, the growth regulator herbicides create a unique situation due to their ability to induce easily observed symptoms at very low doses.

Parts of the state are still quite dry and could use some much needed rain. Some of these areas did receive some much needed rain Monday night (July 10)/early Tuesday morning (July 11).

Bacterial leaf streak is a new disease of corn that was confirmed in the U.S. last year - as if we don't have enough spots to diagnose on corn!  And, as you might expect, a lot of spots and streaks on corn can be misdiagnosed for bacterial leaf streak.

While scouting corn and soybean fields this summer, farmers and agribusiness professionals are encouraged to tweet a photo with the name of the crop disease, county, and state to either @corndisease or @soydisease. The purpose of this Twitter campaign is to track corn and soybean diseases throughout the country for a project called the Integrated Pest Information Platform for Education and Extension (iPiPE).

A few of you with eagle eyes have been asking about this unique-looking caterpillar feeding in soybean. The green body and dark head capsule definitely make it stand out compared to other green caterpillars. It’s the obliquebanded leafroller (Choristoneura rosaceana), a tortricid moth. There have been sightings of obliquebanded leafroller from southern Iowa to southern Minnesota this year.

Despite June typically being one of the wettest months of the year, it is ending to be much drier than normal across much of the state. Besides drier conditions, other common issues showing up in Iowa crop fields include weed management concerns, herbicide drift, nutrient deficiencies, and insects such as Japanese beetles and thistle caterpillars. Iowa State University Extension and Outreach field agronomists give a quick update on what's happening in their respected regio

We are now past the Summer Solstice, which means daylight hours will be getting shorter and we will starting seeing more flowers on soybean plants in fields, which has triggered questions about when we have to stop using dicamba on Xtend beans.

There isn’t really a true “cutoff date” for applying dicamba post-emergence on soybeans. The label tells us to stop applications based on growth stages of the soybean plants.

The six weedy Amaranthus species at the weed garden have grown quite a bit, but I'm not sure how much easier it is to differentiate a few of the species. The six pigweeds are Palmer, Powell's and spiny amaranth, waterhemp, and redroot and tumble pigweed (not in that order!!).

Some much needed rain fell across parts of the state last week, but with the rain came some strong winds and hail in parts of the state. Other areas could still use some rain. Iowa State University Extension and Outreach field agronomists share what they are seeing in the fields and crop progress in their respected regions.


Rainfall totals across the state over the last 7 days. Source: http://water.weather.gov/precip/

Northwest Iowa

Consider attending one of the Nitrogen and Water Week field days next week – June 27 to 29.

Our focus of these meetings is to have attendees ‘kick the tires’ on the tile drainage studies conducted by Iowa State University. 

The USDA Weekly Crop Progress Report showed that Iowa's corn crop is 96% emerged and gave Iowa’s corn crops a 77% good to excellent rating. Soybean planting is 98% completed and 85% of Iowa’s soybeans have emerged. The USDA gave Iowa’s soybean crop a 74% good to excellent rating. The season started off on the wet and cool side, but has gone to being hot and dry.

While searching for Palmer amaranth in a pollinator habitat planting I encountered a few musk thistles.  As I always do when I see this weed, I examined flower heads for the presence of the musk thistle weevil.  This insect was imported to North America as a biocontrol agent for musk thistle.  The adults feed on leaves of thistles, then lay eggs on the heads of musk and related thistle species.

The USDA Weekly Crop Progress Report showed that Iowa's corn crop is 90% emerged and gave Iowa’s corn crops a 77% good/excellent rating. Soybean planting is 91% completed and 62% of Iowa’s soybeans have emerged. The USDA gave Iowa’s soybean crop a 73% good/excellent rating. With planting wrapping up, the focus is shifting to post herbicide applications, sidedressing nitrogen, and first cutting of alfalfa.

Armyworm feeding has been observed in several fields in northeast and southeast Iowa. Most of the fields with the feeding had cereal rye planted last fall and were terminated this spring.

It is that time of year and with the weather conditions we’ve had the last 30 day we should expect to see purple corn, yellow corn, and maybe even some tattered leaves. Mostly the mosaic of corn color is a product of the weather; cooler and wetter. Over the last 30 days, rainfall has been 150 to 200% above normal and temperatures have be a couple degrees cooler than normal across Iowa.