August is here and what happens weather wise will determine if the upcoming crops meet expectations. Then you will know if you had a bad or good year. It is been one of the weirder seasons where everything seems to be off kilter. Most of the crops got planted 1 to 3+ weeks later then normal due to it being either exceptionally wet or way too cool. Late March was more like early May and early to mid-May was still late winter. In some ways getting planted later than normal did not bother farmers as much as normal since soil temperatures never climbed to 50 or 55F until mid-May, weeks later than normal.
How much rain did each area of the Midwest receive this past weekend? Looking at and reading the reports one can see that much of northern Iowa as well at points in eastern Iowa received 2 to 5+” inches over the weekend. It was well received by the lucky farmers, including many in eastern IA who were not as dry as fields in western or central parts of the state. For weeks one could or walk thru fields where various planting time sins were committed, or it was second year corn and the reasons for the glitches were obvious. Now even where sound decisions and management steps were made or taken, the leaves are rolling more, the plants are firing up to the ear and a percentage of the fields are taking on that silvery color. During the past three weeks the corn plants went thru the tasseling, silking and blister stages and most fields were progressing decently. Now that the late blister thru the milk stage has arrived, you can pull the husks down and see how much tip kernel abortion has or will be occurring. At present checks in quite a few fields in the last two weeks were made for kernel and ear kernel development in each. Those kernel stages range from blister to late milk. I’m seeing shallow kernel depth, some bubble kernels, and tip kernel abortion ranging from none to 8, 10 and even 16 rings of kernels shrinking away due to lack of rain and the constant high 80 to mid to high 90-degree temperatures. Once you lose those kernels the plant may partially compensate by forming deeper grain on all of those kernels. Anyone who has walked into the cornfields the past few weeks can verify that achieving yields close to those of last year is not likely to happen. We had a slight temperature reprieve but not enough rain in the stressed areas.
Stress Days
Elwynn Taylor gained further fame by summarizing the multi-year data of effect of cumulative temperatures in excess of 86 degree on final corn yields. These Stress Degree Day or SDD calculate the daily high degrees above 86. Once that figure tallies above 140 the corn yields dropped. How far the drop is then dependent on moisture sufficiency or deficiency. The expected yields are projected in eight-bushel increments. I was checking out the Iowa Mesonet charts and could not find out the current figures for Aug 8th for the different parts of the state. In past years we normally tally fewer than ten days at or above 90 F. This year nearly every week since early June has contained four to seven days above that mark.
Planning for Stress Conditions
In my preplant meetings with growers I had to sum up my observation that in the past 15 years we have seen two to three weeks of very warm weather in mid to late March where temps are in the 60s and get farmers fired up and excited to get started with spring work. Then in mid- to late April conditions cool off with temps in the high 30s to low 40s and very little sunshine. It may or may not rain or snow during that two to three-week time period. Then around May 1st to the 5th or so, the temps increase dramatically. It may rain harder, but not as often and erosion can be severe during June. Then between June 15th and mid-August things turn hot and dry, often placing the corn crop under heat and moisture stress. From visiting with a friend who works for NASA running an observatory I know we are actually in a cooling trend. However, for whatever reason the extremes in rainfall and temperatures are more the rule now and have followed that pattern.
In those planning meetings we talk about hybrid selection and root architecture characteristics, the value of using mycorrhizal fungi to expand the root zone, the use of Biological seed treatments like BioEnsure and SabrEx, the use of foliars and minerals to tolerate heat or drought like Phonix-Respite-Solace, calcium silicate and its 36% increase water use efficiency, and the use of zinc and its value to help plants tolerate drought conditions. When the top nutrient expert from Australia calls zinc his drought mineral, you have to pay attention. In field adjustments to the planter can help dramatically. One selling point for the use of strobe fungicides is that they can act as stress mitigators and keep canopy temps 8 to 10 degrees cooler for 15 to 20 days. This will reduce the formation of the Ethylene hormone, which can act as the precursor to Abscisic acid, which can cause SB pods to drop off as the abscission lay will form. When I spent time at Bayer headquarter I was able to spend part of one day with Dr. Isolde Hauer Hahn, their chief fungicide physiologist. She totally opened her books and showed me the data on the cooling effect on plants. But at what cost vs using the Phonix type product which was developed by top Biochemist Frank Dean. All of these steps are more effective when a good biological mix has been applied in-furrow or broadcast, or the Haney soil analysis has verified that your soil health is good.
Late Season Management
After the corn crop gets too tall for tractor traffic, in season trips to maintain or boost yields are generally not made. Fungicides may be applied and a bit of foliar feeding will be done, primarily with slow release forms of N. There have not been as many planes flying on fungicides as the drier fields and lack of longer lasting dews are not as conducive to fungal infections. Both incidence and severity of fungal and bacterial diseases are minimized. Goss’s Wilt will be the exception as there is always enough moisture within the stalk for the bacteria to survive. So far fungal leaf disease pressure has been light and the ones still appearing have been GLS, Eyespot and small spots that may be early anthracnose. There have been reports of Tar Spot being identified and confirmed, but not at high levels. Without more rain most farmers in the drier areas may give up spending more money on the crop. The exception will be those who have enough livestock and place a higher value on their known quality grain.
The soybean crop generally has more potential left and more bushels could be added that aid in grain fill. Plus, as we move into mid-August we see more dew and early morning dews that allow Septoria, Downey Mildew, and Frogeye to appear and approach yield reducing levels. Given the fact that both fungicides and late season application of mineral products by actual producers have been shown to be profitable, scouting and using products geared to foliar applications can produce a nice ROI. Using products that have systemic movement into and within the plants is a must. You must know your water quality and best products to use to make adjustment. Making judgment calls as to the best time to make application is important. Making applications in the midafternoon when thermals and high temperatures peak are not wise. Those are when most universities make their applications, leading them to say late applications are not valuable.
In the past few weeks I have looked at many bean fields that have received mineral and biologicals that either increased mineral levels in the plant to boost seed size or added branches to compensate for shorter stems due to late planting. Seeing a high frequency of plants with 4 to 7 side branches and a huge number of small and filling pods tells us that higher yields can still be achieved.
Botanical Insecticides
We work with a newer blend of companies from Eastern IA, central ILL and SE S Dakota, that now have products that fit a number of different crops or needs. I see one big need. Most people that work outside have commented on Face fly numbers and their boldness has reached new levels. In my own yard the number of face flies that land on any and all exposed flesh is greater than I have ever experienced.
Working outside with short sleeves leaves you wanting a flyswatter in one hand at all time to swat them. Dogs and cattle are doing everything possible to avoid their attacks. When guys are working on machinery and need three or four hands to hold a piece in place, you would have to tolerate their bites. There is now a concentrated botanical insecticide called BigShot which is a micro-encapsulated mix of three essential oils extracted from organically grown plants available. They are actually selectively breeding for increased yields of these oils to keep prices affordable and boost efficacy. None of the health-related side effects from DEET containing products accompany this insecticide. It is also labeled against ticks and spiders while being safe to pollinators and for kids. One well known mineral expert and friend tested BigShot and just a small shot of an organic pyrethroid to get rid of his Japanese Beetle populations and problems. Orchard and berry producers will like having this product for their use.
Bob Streit is an independent crop consultant and columnist for Farm News. He can be reached at (515) 709-0143 or www.CentralIowaAg.com.