Crop Update August 9 - August 15

 #Drought17, late season hail damage, weed escapes, and soybean aphids seem to be the big issues ISU Extension field agronomists are seeing in fields across the state this past week. Read on for more information about your region's crop progress and field conditions.

Northwest Iowa

Joel DeJong (Region 1): “The newest drought monitor does a good job of showing the areas where moisture stress is causing the most problems. There have been just a few fields harvested for silage so far, most from light soils, but at least one from a corn-on-corn field on decent soils. Corn is mostly at the dough stage (R4) at this time, according to the fields I have visited. Soybeans are filling pods, and are now in the early R5 stage. Soybean aphid reports seem to be few in the southern part of the NW corner, but more frequent as we move north. I am amazed at the differences in yield potential in NW Iowa. Some fields look quite good while others will be collecting crop insurance checks, I am quite certain. There will likely be about as wide of a yield range in NW Iowa this year as I have seen in a few years. That yield range won’t only vary from field to field but within fields as well.”  

North Central Iowa

Angie Rieck-Hinz (Region 3): “Corn is mostly at R4, dough stage, although I have seen some corn at R5, dent, as maturity is progressing quickly under the dry conditions. Soybeans are R4 to R5 and soybean aphids continue to be sporadic in pressure. Continue to scout soybeans for aphids through the R5.5 stage. The biggest concern out there now is the weed escapes we are seeing in both corn and soybeans. Timing was crucial this year on post-application and in most cases I think the weeds were too big and the hot weather and lack of rain helped to make the weeds more difficult to kill. I also scouted two CRP pollinator fields for Palmer amaranth this past week. I am happy to report I did not find any Palmer, but I encourage landowners to continue with appropriate maintenance such as mowing to reduce weed pressure in these plantings.  And, again, the broken record of continued spotty rains, although some areas received nice rains early the morning of August 14.”

Northeast Iowa

Terry Basol (Region 4): "Corn here in NE Iowa continues to look pretty good. Most of the corn is in the dough stage (R4), and according to NASS (National Agricultural Statistics Service), as of August 14, 9% of the corn has dented (R5) in NE Iowa. Cooler temperatures than normal for the last couple of weeks has slowed down the development of the corn. The cooler temperatures have also allowed low stress conditions for the crop, resulting in the crop being able to attain higher kernel weight. Foliar diseases remain at low levels. Soybeans are primarily at the R4 stage in which there is a pod that’s 3/4” long at one of the four uppermost nodes on the main stem. There are some soybean fields that are beginning the R5 stage (seed is 1/8” long in the pod at one of the four uppermost nodes on the main stem). According to NASS, 66% of the third cutting hay has been harvested for the area. The last couple of weeks have been fairly dry as far as precipitation goes. According to the Iowa Mesonet, we received about 0.8 inches of rain from July 31 through August 14 at the NE IA Research and Demonstration farm near Nashua."

Southwest and West Central:

Aaron Saeugling (Region 6): “Corn silage chopping has begun on a few fields here in SW Iowa. Corn is showing signs of early maturing and lower leaves are beginning to yellow in poor areas of fields. Various reports of poor kernel filling are coming in. Most corn is in the milk (R3) to dent (R5) stage. Cool weather has slowed the damage due to the dry conditions. Soybeans are in the R3 (begin pod set) to R5 (begin pod fill) stage and some yellowing has occurs on poor soils.  Most spraying activity has stopped. Moisture is needed to fill the top pods. Unfortunately, we have had no significant rain fall over the last week, and we could really use some in most areas. Hay and pasture conditions continue to deteriorate with lack of rainfall and adequate subsoil moisture across most of the area.”

Southeast and South Central: 

Rebecca Vittetoe (Region 8): “Rain continues to miss my counties that are the driest, leaving some of the driest areas with not having accumulated an inch of precipitation for 35 to 42 plus days. The dry weather is having a direct impact on the corn and soybean crops, pastures, and alfalfa. Corn is mostly in the R4 (dough) to R5 (dent) stage. The cooler weather is helping to prolong the grain fill period some. Many farmers have started to either green chop or chop corn for silage. If you are curious on what the moisture is on the corn you would like to make into silage, you can do a test using a microwave. Soybeans are in that R3 (begin pod set) to R5 (begin pod fill)  stage. We are in that critical window for soybeans, and a decent rain would really help with pod fill. Some farmers are thinking of harvesting soybeans for forage. Be talking to your crop insurance provider and also double check pesticide labels to make sure it is legal to do so.”

The number of recent days till accumulating one inch of precipitation. The yellow and black areas represent 35+ and 42+ days, respectively. Source: Iowa Mesonet. 

Virgil Schmitt (Region 10): “The counties I cover generally received less than an inch of rain during the last week. However, a severe hail storm hit parts of Clinton County late Thursday. Lack of rainfall continues to be a problem along and south of Highway 92. Corn is mostly R4 (dough) and soybean are mostly R5 (begin pod fill) and generally look healthy except for weather-relates stresses. Issues last week are continued concerns about Japanese beetles, concerns about dicamba injury to soybean, and waterhemp emerging from the soybean canopy.”

    
A hail storm went through part of Clinton County last week Thursday (8/10/17) causing damage in corn and soybean field. Photos by: Ross Kleppe.

Find your local ISU Extension and Outreach field agronomist here!