Renewable Farming

Ways to help corn and soybeans endure a hot, dry July – August stretch

A couple of foliar-applied products new to the Midwest offer corn and soybeans ways to withstand stretches of hot, dry weather.

July 9, 2020 — Last February we published a preview of stress relievers from Spraytec, a Brazilian firm. We’re watching fields now for further evidence that nutrient elements, fully assimilated, can keep corn healthy through hot, rainless days of early July in our region.

Naturally, our long-held prescription for helping crops endure wet or dry stress is a healthy, biologically alive soil. One that’s rich in active humus which quickly sponges up downpours (like the deluge that roared across northeast Iowa this afternoon) and holds that moisture in the root zone. But building that soil is a gradual process, and many soil types such as sandy strips can’t cling to moisture very well. 

This is one reason Renewable Farming is a distributor of Spraytec products, which have seen strong demand this spring and summer. (For details, call Erik at 319-610-2506 or e-mail

Foliar fed with Spraytec’s Fulltec zinc and Impulse.
Photo taken July 8 when temps were near 90 F.

The nearby corn photo was taken July 8 near Moorland in Webster County, Iowa. Drew Ewing, field rep for Spraytec, says many fields around this one showed severe rolling — indicating a loss of grow time. But this field remained vigorous, with no rolled leaves or leaf striation signaling nutrient deficiency.

This corn had been foliar-fed twice:

About June 1 — At V4, the four-leaf stage, with Fulltec zinc. Its spec sheet indicates “The phosphates of Mn and Zn increase plant tolerance to diseases and stress.”

On June 11 — At V6, with Spraytec’s Impulse for corn. 

Drew also sent us a report from another Webster County, IA grower, Dan Sullivan, who said he’d encountered dry weather at planting. “That led to uneven emergence, so my corn developed with wide variations in height.  I applied Spraytec’s Impulse at V5, then Fulltec zinc at V7.”


Dan Sullivan

Dan’s observation was that those foliar feedings helped the field “even up” — become more uniform in height and color.

Note: We’ll update this report as more field observations arrive. Renewable Farming is working with Spraytec, via Drew Ewing, to provide field reports.

We’re also working to gather Midwest field evidence of a biological product called BioEnsure, which works synergistically with crops to help withstand dry weather and other stresses. Last Jan 22, Iowa crop consultant Bob Streit conducted a farmer seminar which included Rusty Rodriguez, the innovator behind Bioensure, to explain how he discovered the ability of “endophyte” microorganisms to help plants cope with stress. The video of Randy’s presentation is available from Central Iowa Agronomics. 

Early this season, Bob Streit worked with a north central Iowa farmer to test the BioEnsure endophytes on corn. It was foliar-applied with BioEnsure June 8. That treatment also included 1.25 gal. of a solution which contained the recommended rate of Fulltec Cube, a product from Spraytec.

Now as of July 10, after three rainless weeks, most of the area’s corn on lighter soils is rolling late in the day and showing some lower-leaf firing.

Corn in this treated 80-acre field is tasseling — except for the endrows, which were not sprayed with the endophyte from Adaptive Symbiotic Technologies plus the Fulltec Cube product from Spraytec.

The 80-acre field is 107-day corn, planted April 22, and among the farmer’s earliest to tassel. The photo below shows that the untreated endrow corn is about a foot shorter than the treated corn, and shows only a few tassels.  Even though it’s late this season for a remedial spray of BioEnsure, it’s an indicator of possible “insurance” to use on stress-prone soils next season and beyond. Actually, the researchers at Adaptive Symbiotic Technologies, makers of BioEnsure, tell us that recent trials have shown that BioEnsure and a companion microbial product, BioTango, do confer stress resistance when applied as late as the onset of the reproductive phase.

Since this field was foliar-fed a combination of two products — BioEnsure (an endophyte stress reliever) and the mineral and biostimulants in Fulltec cube, there’s no clear-cut way to attribute the corn’s performance to either product. But certainly the combination shows benefits. The grower also treated some test strips with GPS coordinates, so the combine yield monitor map should reveal more data.

Main 80-acre field in north central Iowa was sprayed with bioensure. Endrows were not sprayed.

Another photo (below right) taken in late afternoon of July 10, with temps approaching 90 F.

and three weeks without rain, shows a closeup of the corn treated with Bioensure and Fulltec Cube.

There’s no firing of lower leaves and no rolling.

Directly below is a chart extracted from the website of Adaptive Symbiotic Technologies, the company which markets Bioensure. It shows that the more stress a crop encounters, the greater the yield gain compared with unprotected crops.


Yields by levels of water and/or heat stress.
Higher stress gave treated corn a larger advantage.
Update on this field July 27 (Photo below):  Still no leaf rolling or firing, although there has been almost no rain here through July.  Corn in untreated endrows is rolling tight in the afternoons, such as the warm afternoon July 27 when this photo was shot.  The grower also noted that where Bioensure was applied earlier, there are very few fungal lesions on the leaves — which are common late in the season. He wonders if the Bioensure fungal endophyte, which lives in the crop’s vascular system, becomes a natural defense against pathogenic late-season fungi.