Crop Update July 5 - July 11

July 10, 2017 11:57 PM
Blog Post

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). Well some areas of the state are very dry other areas have been hit hard with storms, with the most recent area being up in north central Iowa. Iowa State University Extension and Outreach field agronomists share a quick update on what's happening in their respected regions around the state.  

Northwest Iowa

Joel DeJong (Region 1): "Rainfall in the NW corner of the state remains very spotty, with some areas continuing to miss significant rain since about the 20th of May. Most of the area is classified as Abnormally Dry on the US Drought Monitor, with a segment through the middle listed as moderate drought. At the time of this writing, we have missed almost all of the rain that covered much of Iowa early this week, except the counties in W.C. Iowa. Corn has been rolling daily in some fields in the region, and now we are seeing a few tassels. There is quite a bit of concern about what will happen with corn experiencing stress, and the hot forecast. At the same time, other neighborhoods look very good! Soybeans are blooming, and growth in really taking off in areas that have received rain. There has been some disappointment in the effectiveness of the post-emerge herbicides this year.  Additionally, several calls about dicamba herbicide drift have been received, with a couple more on dicamba tank contamination problems."

According to the U.S. Drought Monitor, parts of Iowa are either abnormally dry or are in a moderate drought. Source:

Paul Kassel (Region 2): “The corn and soybean crop continues to look good for most of my area. The lack of rainfall is being a concern. Moisture stress is evident in both crops in light soil areas. The western half of my area is listed as abnormally dry by the US Drought Monitor. The Drought Monitor lists parts of Sac county as moderate drought. Dicamba drift injury to non RR Xtend soybean varieties has occurred in a few fields. Most of the cases are not real severe but have been a concern to the farmers who have received the drift injury. The soybean crop is recovering from this injury fairly well in most cases."


Dicamba drift injury to a non-RR Xtend soybean variety in Clay county. Photos by Paul Kassel. 

Northcentral Iowa 

Angie Rieck-Hinz (Region 3): "Rainfall continues to be spotty across my 9 counties. The western side of my area is dry and creeping into the drought monitor and the northern part continues to receive spotty rains that rain from 0.3 to 1.5+ inches.   We had a major wind/hail event on Sunday night, July 9th.  See the picture below from near Klemme. Corn is from V16 to R1.  I have seen no disease pressure in corn.  Some places that are dry are exhibiting nitrogen firing in the lower leaves.  This is not due to lack of N, but lack of rain. Soybeans are mostly R1, up to R3.  There has been a lot of talk about spraying for aphids, but most people I have talked to have not seen aphids and I found no aphids last week after being in a dozen bean fields. Let’s pause and think about how that insecticide can’t kill what isn’t there. I have been in several fields where farmers question the efficacy of PPO inhibitor herbicides.  We do have documented PPO resistance in Iowa. In these situations I feel the weed size was too large when sprayed."

Hail event near Klemme, IA, overnight July 9.  Photo from Angie Rieck-Hinz. 

Northeast Iowa

Terry Basol (Region 4): “Corn on average, is looking good in NE Iowa, with most of it around V13 to V15. For the early planted fields, you can begin to see some tassel emergence. Soybeans are looking a lot better now, and are all flowering. Most fields are in full bloom (R2), which is when an open flower can be found on one of the two uppermost nodes on the main stem of the plant. According to the Iowa Mesonet, the NE IA Research and Demonstration Farm here at Nashua has received 2.8” of rain from June 25th to July 11th. Included in that, is 1.2” of rain that was received the evening of July 10th." 

Central Iowa

Mark Johnson (Region 7): “As I drove around last Thursday and Friday, I noticed a lot of fields with pockets of tassels showing. From my observations, it looks like pollination timing may be quite variable in many fields this year. I have had only a few calls about dicamba injury to soybean. Of the 9 counties I serve, 8 of them are in the abnormally dry category on the drought monitor. The lack of moisture is causing corn leaves to roll, especially during the hot part of the day.  In my travels, I've also noticed that the compacted areas and the sandy areas of fields are easily spotted, due to the extent of the leaf rolling.  I have noticed a few soybean fields that look as though there were no pre-emerge herbicides and no post so far as the grassy weeds are getting tall and some of the broadleaves are taller than the soybean plants. However, overall, there are a lot of soybean fields and are quite weed free and are very clean."

Southwest and West Central:

Mike Witt (Region 11): "Overall moisture has been hit and miss in West Central Iowa with amounts from 0 to 2 inches of rain reports over the last few weeks. Crops are showing some signs of water stress in areas, but it is not widespread. Maturity of soybeans is ranging from R1 to R2 while corn is between V18 and tasseling. Tassels in fields are not uniform which represents the unevenness that the fields have experienced throughout the growing season. Insects of note in the area have been Japanese Beetles and grasshoppers which are starting to increase in numbers. Palmer Amaranth still continues to be found in 2016 planted CRP fields. Now is the correct time to be scouting for the weed.  Herbicide drift, especially from dicamba applications, has been noted throughout the area. Contact your local field agronomist if you see an issue to report within your fields."  

Southeast and South Central: 

Rebecca Vittetoe (Region 8): "We could definitely use some rain in this part of the state. All of my counties are either abnormally dry or in a moderate drought according to the U.S. Drought Monitor. Rain showers have been very spotty. Thankfully some counties received some much needed rain Monday night/Tuesday morning.  Corn is either very close to tasseling or right at tasseling (VT) and most soybeans are R1 to R2. Both the corn and soybeans seem smaller (height-wise) this year. Pastures are looking tough due to the lack of moisture. It's not uncommon to find fields or parts of fields showing signs of potassium deficiency, especially in fields with low potassium levels to begin with. Keep an eye out for nitrogen firing in the lower leaves, which is not because of a lack of N, but rather lack of rain. Besides the moisture stress, other things to keep your eyes out for in fields include Japanese beetles, spider mites, potato leafhoppers in alfalfa, and herbicide drift or damage. I've had a few dicamba drift calls and also some calls on malformed soybean leaves due to a group 15 herbicide included as a residual in post applications." 

Japanese beetles emerge over about a six-week period and are starting to appear in corn and soybean fields. Leaf feeding on soybean and corn silk clipping (before pollination) are of concern. Photo by Rebecca Vittetoe. 

Meaghan Anderson (Region 9): "Most corn in my area is very close to tasseling (VT), while some fields already have 50% of plants with silks out (R1).  Fields look good overall, but the south and western portions of my counties need rain, especially with the warm temperatures and pollination occurring/approaching.  Most soybeans are at R2 or full flower.  Some fields look fantastic and are completely canopied, while others look very tough, especially those late planted.  Japanese beetles, spider mites, and dicamba injury have all been big issues in soybean fields in the last week."

Virgil Schmitt (Region 10): "During the last two weeks, we have had between 0.5 and 2.0 inches of rain, depending on location. In general, areas along and south of Highway 92 are the driest. Corn is generally V16 to V18. A few fields began displaying tassels last week. Corn condition is generally very good. Soybeans are mostly R1 to R2. They have seemed to struggle some so far this season. Many people have observed that corn looks very good but the soybeans look poor. The big issues over here are Japanese beetles, grasshoppers starting to make their appearance, and soybeans with malformed leaves, with dicamba drift high on peoples’ list of suspected causes."

Map showing rainfall totals for Iowa over the last two weeks. Source:  

Find your local ISU Extension and Outreach field agronomist here!


Rebecca Vittetoe Field Agronomist in EC Iowa

Rebecca Vittetoe is an extension field agronomist in east central Iowa. Educational programs are available for farmers, agribusiness, pesticide applicators, and certified crop advisors.

Areas of expertise include agronomy, field crop production and management of corn, soybeans, and...