Renewable Farming

WakeUP Summer can help you control late-season weeds, but resistance is rising

This time of year, we get calls from farmers asking about a wide range of weedkiller combinations to fight weed escapes. This summer’s persistent rains and muddy fields make their challenge tougher than in most seasons. We wish we had a magic bullet for you. One thing we do know: Our WakeUP Summer reduces water surface tension for smoother leaf coverage, and speeds leaf absorption of your chosen herbicides. WakeUP is not a herbicide/pesticide. It’s a surfactant/adjuvant.

July 2, 2018   By Jerry Carlson — Farmers’ response to weed escapes has often been to broaden their tank mix of postmerge herbicides and increase rates per acre. In the final paragraph of this report, we’re inviting you to e-mail us your own workable ideas — or mixes that were busts. 

Postmerge weedkillers are more effective with uniform leaf coverage and rapid systemic penetration. WakeUP Summer does that job more efficiently than any surfactant we’ve tested. However, effective herbicide choices are dwindling as weed resistance rises. Successful Farming reported a few days ago that the University of Missouri has found some waterhemp resistant to six modes of herbicide action. 

Today, an Iowa consulting agronomist, Larry Eekhoff, sent us the nearby photo of waterhemp sprayed with this herbicide mix and rates per acre:

6.4 ounces Fusilade (Syngenta, fluazinfop-p-Butyl)

3 pints Flexstar Gt (Syngenta, fomesafen/glyphosate)

1 pint Fusilade (Syngenta, Fluazifop-p-Butyl)

1 pint Medal (Syngenta, S-metolachlor)

The four-herbicide blend also had

2 pounds of soluble AMS

4 ounces of Biodyne’s potassium product, Respite

3.2 ounces of Winfield’s spray drift reducer, Interlock

6 ounces of Renewable Farming’s WakeUP Summer.

As shown in the photo, most of the waterhemp sprayed with this blend on the morning of June 30 was toast by July 2. Other waterhemp weeds right beside the dead weeds had a few dings — but were growing almost undamaged.

The consultant’s conclusion: “It sure looks like resistance” to the five modes of herbicide action.

The University of Missouri weed scientist’s prescription in such super-resistant cases: Hand rogue the field to clean up the survivors, and carry live weeds from the field if the seed has a chance to be viable.

(That was the prescription my Dad gave me to clean up cockleburs in our soybeans in 1948, when I was 12 years old on our southwest Iowa farm. “Jerry, hitch up the Ford 8N to the hayrack. Pull the rack through the field; stay between the rows so you don’t mash down beans. Pull every cocklebur and toss it on the rack. Bring back the hayrack to this gravel area in front of the barn. Unload it. Go back for more burrs. Don’t quit until you can’t find any more weeds in the field. Then in three days, scout for those that were hiding in the beans on your first trip.” 

Three hayrack loads later, I had accumulated a huge pile of cockleburs in the barnyard. After they dried for a week, I had great satisfaction in lighting the fire and watching them roar, crackle and pop. That was my July 4 celebration.)

Since 2008 we’ve focused our WakeUP research almost entirely on getting nutrients into plants. However, we have had experience with a few foliar herbicides, out of necessity in wet seasons like this. One test was whether a tank mix of Cobra and WakeUP Summer is more effective with — or without — MSO (methylated seed oil). Farmers often ask us about that.

Generally, we’ve found that using WakeUP as the only surfactant gave Cobra herbicide more effective coverage and absorption than a combination of WakeUP plus an oil-based “sticker” blended in the tank mix. Usually the goal of a contact herbicide is to translocate the active ingredient into the plant metabolism soon as possible, and make the herbicide’s active ingredient rain-fast in five or 10 minutes. WakeUP does that, especially if you use 20 gallons of water per acre (or a tad more). Reminder: WakeUP is not a herbicide; it just helps herbicides do their jobs.

We also have found that using Pursanova-energized water improves systemic absorption of contact weedkillers.

Leaving out the oil-based sticker also tended to reduce soybean leaf burn in several of our tests. The two photos below resulted from an obviously late-season rescue application of Cobra plus WakeUP Summer in August 2014. Note the minimal leaf burn on soybeans.

Larry Eekhoff, the crop consultant  who took the above photo of resistant waterhemp, is also tracking field progress with other technologies using a drone with Normalized Difference Vegetation Index (NDVI) software. He’s watching several field trials with in-furrow combinations of Biodyne products, Vitazyme and WakeUP.  Watch this site for reports as the season unfolds.

Please e-mail us your experience with herbicide workable answers, or things to avoid, coping with weed escapes. For example, an Illinois farmer advises us that he prefers to spray Cobra or Flexstar in late afternoon, so hot sunshine won’t aggravate leaf burn on the beans. Just send me an e-mail, and also include permission to post your suggestions as an update to this report, if that’s OK with you. Thanks!  

A label rate of Cobra and 5 ounces per acre of WakeUP Summer on soybeans, 2014. This photo and the 
one below were taken in the same field, about six days after spraying.