All

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.

Monarch butterflies are an iconic species, known for their vibrant orange color and magnificent migration. Monarchs overwinter as adults in Central Mexico and fly to Texas and Oklahoma in the spring. Females lay eggs on milkweed plants, and the caterpillars feed on milkweed for about two weeks. After pupating as a chrysalis, the adult monarchs emerge and continue the northbound migration. Eventually, they reach Iowa around April-May and Canada by June.

Currently 92% of Iowa’s corn crop has been planted and 62% of the soybean crop according to Monday’s USDA Crop Progress Report. However, the wet weather across the state has put #Plant17 and other field activities on hold as farmers only had 2.3 suitable days for fieldwork during the week of May 15 through May 21. 

In 2017, ISU is reporting black cutworm (BCW) peak flights by county and providing degree day resources for more personalized cutting prediction dates using actual accrued degree days for a specific location. We first reported on BCW peak flights in the ICM News in early May.

Recent requests for information has prompted us to share what we know about "jumping worms," another in a long list of invasive species that could have a negative impact on our landscapes and natural areas. In the words of Gilda Radner, "It's always something. If it isn't one thing – it's another."

You might not think insects would make great parents, and in general, you would be correct. Most species just drop eggs and keep moving. But there are a few species, particularly true bugs (Hemiptera), that do try to protect their young. Parental care ranges from hiding eggs, to providing food, to forming life-long bonds. Not surprisingly, females often provide the care.

#Plant17 is progressing across Iowa. Following a period of cooler and wetter weather, most farmers have been able to get back in the fields over the weekend and either resume or start planting. According to Monday’s USDA Crop Progress report, Iowa had 52% corn planted and 19% of soybeans for the week ending of May 7, 2017. Iowa State University Extension and Outreach field agronomists report planting progress and field conditions in their respected regions.  

This week, a couple Iowa crop consultants reported grubs are easy to find this spring. I assume they are digging in crop soils to evaluate seed germination. Last year, there was some grub feeding injury in seedling corn and so it is a good time to look for seed and seedling injury around the state. Learning how to distinguish annual grubs (e.g., masked chafers and Japanese beetle) from true white grubs (May and June beetles) with a longer life cycle is important.

The multicolored Asian lady beetle, also known as Harmonia axyridis, is a common insect in the ag landscape and also in urban areas. It’s often confused with plant pests, like Japanese beetle. Generally, it’s a good thing to see them around because the larvae and adults are predatory, and eat soft-bodied insects like aphids.

The cold, rainy weather this past weekend has presented challenging conditions for corn fields that have already been planted. Now that the weather is improving it’s good to start thinking about what the consequences might be and what to look for. Heat unit accumulation has been negligible since April 26. Rainfall had been near the climatological average prior to the recent rains. The effect of this weather pattern has resulted in April planted corn taking more days to emerge.

The recent wet weather in Iowa has prompted people to ask me if insects can breathe under water. In short, most insects can survive under water (or in saturated soils) for short durations. Of course, how insects can accomplish this is complicated and full of entomological jargon. In some ways, insects breathe like us and in other ways, insects breathe in a completely different way.

There are several challenges to controlling Palmer amaranth in CRP, including: