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Scouring rush and field horsetail are two species in the Equisetum genus. These are primitive plants that produce spores rather than seeds, but they spread primarily by underground rhizomes. Until recently these two weeds were found primarily in roadside ditches, but the reduction in tillage has allowed them to spread into crop fields.

As Merle Haggard said in his song, Under the Bridge, “you’ll find some great grub feedin’ here below.” I got a couple calls about grub injury in seedling corn last week and how to identify annual grubs (e.g., masked chafers and Japanese beetle) from true white grubs (May and June beetles) with a longer life cycle.

Iowa has 80% corn planted as of May 8, according to Monday's USDA Crop Progress Report, up from 57% the previous week. The report shows that soybeans planted also made a notable jump from 7% complete on May 1 to 29%.

Many farmers were able to get back in the fields this weekend with a break in precipitation. Others continue to be affected by wet conditions. Iowa State University Extension and Outreach field agronomists report planting progress and field conditions in their area.

My home drinking water source comes from the Xenia Rural Water District. Depending on where you are located within the district, your water comes from an alluvial aquifer, or surface water from the Raccoon River or the Des Moines River. The water is treated and delivered to my home and, according to their web page, over 9,400 other customers.

As of May 1, the USDA reported 57% of corn had been planted in Iowa. See below for area conditions and planting progress around the state from Iowa State University Extension and Outreach field agronomists. ISU Extension and Outreach specialists provide recommendations and resources based on current condition.

The United States has almost half of the corn crop planted for the season at 45% complete, according to the United States Department of Agriculture (USDA) Crop Progress Report on May 2.

The USDA reported 57% of corn planted in Iowa as of May 1, with the 5-year average being 28%. The weekly report had 7% of corn emerging in Iowa, which is 4% ahead of the 5-year average.

You should visit the newly formatted and revised Corn Nitrogen Rate Calculator (CNRC) website. The site has a new url ( http://cnrc.agron.iastate.edu/ ). For Iowa, there are now two regions, the Main Iowa area and a Southeast Iowa area (SEIA) – see the descriptions below. The Iowa corn following corn and corn following soybean N rate response trial databases have also been updated, so suggested N rates have changed somewhat.

Accelerated, early planting in some parts of the state increases pressure on applicators of preemergence herbicide to speed up sprayers to cover a larger numbers of acres. Increased speeds increase boom pressure for existing nozzles, and can tempt applicators to increase boom height. Both increase drift potential. 

If travel speed increases, consider using a slightly larger nozzle size to maintain desired droplet size and keep spray booms within 2 ft of the target.

Corn typically requires 90 to 120 Growing Degree Days (GDD) from planting to emergence. Of course this GDD range assumes adequate soil moisture and varies with planting depth, tillage system and residue cover. As a rule of thumb, if 120 GDD have accumulated since planting and seedlings haven’t emerged, check the condition of planted seed ASAP. For example, in west central Iowa we have had around 120 GDD’s since April 11th.

I’ve received a few questions asking what the purple weed is that is appearing in the landscape. It is probably either purple deadnettle (Lamium purpureum) or henbit (Lamium amplexicaule).

I received one report of a cereal rye control failure this week as temperatures warmed and rye growth resumed. Some follow-up questions and photos showed that concerns regarding burndown applications during cool, early-spring conditions have merit.

Statewide Summary

Weather conditions this past week (April 13-17) kicked off corn planting for many farmers throughout the state. As soil temperatures rose above 50°F towards the end of the week, farmers were able to dive into fieldwork and planting corn.

See statewide planting progress and field conditions across Iowa here.

Below, Iowa State University Extension and Outreach specialists provide recommendations and best practices going into the planting season:

It seems that anhydrous ammonia (AA) applications and planting may fall very close together on the timeline of events this spring. This could be concerning with drying soils and lack of significant rainfall chances in the near future.

Important notes to remember:

1) Application procedures are key to avoiding injury to corn seedlings. Deep injection (6-8 inches) and a good seal on the knife track are the best ways to avoid AA placed in or movement into the root zone.

I've had a lot of questions/discussions this week about planting corn. I had some growers get started Monday, some others were going to start towards the middle or tail end of this week, a few were going to wait until Monday, and a few were undecided. When to start planting was probably worthy of a blog, but that horse has sailed out of the barn in my part of Iowa.

Bean leaf beetle adults are susceptible to cold weather and most will die when the air temperature falls below 14°F (-10°C). However, they have adapted to winter by protecting themselves under plant debris and loose soil. An overwintering survival model developed at ISU in 2000 is helpful for predicting winter mortality based on accumulating subfreezing temperatures. Predicted mortality rates in Iowa were low during the 2015-2016 winter and ranged from 35-68%.

Research can be frustrating. For the past 5 years, my lab has been evaluating seed treatments on soybean. In an effort to detect an effect of seed treatment on soybean stand and yield, in 2015 we planted our trials very early (mid-April). A few days later, it rained, soil temperatures dropped below 50 F and we thought we had nailed it!  Finally we would have great data. Wrong!!! Our ICM News article summarizing these data should be posted to ICM News soon.

As I did some reading in preparation of writing this blog, I found there are various definitions of soil health. And I am sure for as many definitions as there are, we each have our own ideas as to what defines soil health.

Meaghan and Bob’s blog posts on weeds, and seeing a floater spraying yellow herbicide in 30 mph winds on Monday, reminded me to do an update on our newest problem child in the weeds world, Palmer amaranth. While we hoped that the few infestations scattered across Iowa could be contained, unfortunately a few weeks ago I found out that—in Harrison County anyway—Palmer has increased its range and seed bank.