H2O Perfect Timing

Compatible glyphosate tank mix with Zn/Mn

Published in the July 2009 Issue Published online: Jul 03, 2009

As the second year for glyphosate-tolerant sugarbeets gets under way, a recent advance in nutrient formulation technology is producing more tonnage in glyphosate-tolerant beets by averting the herbicide’s chelating activity.

The nutrients provide similar benefits in conventional beets, but the formulations are intended to help growers maintain the herbicidal effects of glyphosate while enhancing crop development.

 

Zinc & Manganese

Glyphosate is now so widely used on so many crops that the focus of research has become how to help growers get even more benefit and performance from it. One way is to overcome the problem university research has demonstrated—that glyphosate molecularly combines (chelation) with metals such as zinc and manganese.

This locks the nutrients up so they lose mobility and efficacy when applied to the crop at the same time as glyphosate.

Glyphosate also interferes with the plant’s ability to pick up zinc or manganese from the soils.

Zinc is the cornerstone for leaf, root and vascular system development while manganese is a key player in photosynthesis, nitrogen assimilation, disease and stress resistance and other essential bio-chemical reactions within the plant. To effectively provide these nutrients to glyphosate-tolerant crops, growers have had to wait eight or more days for the residual glyphosate in crop tissue to move out through root exudates, and then make another pass across the field with the nutrients.

 

Dr. Huber

In the new Sysstem-Ready formulation, zinc and manganese are linked to phosphite ions that resist glyphosate chelation, enabling rapid nutrient absorption and mobility within the crop plant. Phosphite, which is more readily absorbed into plant tissues than phosphate, becomes the carrier for the nutrients when used in the Sysstem-Ready foliar sprays.

This makes the nutrients available during peak demand, increases the flush of new roots, and accelerates maturation to produce better yield. Also, the phosphite formulations are not antagonistic to glyphosate, which typically loses some weed control activity when chelation has occurred in a tank mix with nutrients.

Dr. Don Huber, professor emeritus in the Botany & Plant Pathology Department of Purdue University, is one of several experts in plant physiology and metabolism who have studied how nutrients enter, translocate and act upon the plant, interact with one another and impact the surrounding soil rhizosphere.

He has spent several years working on the problem of glyphosate immobilization of nutrients.

“Early-season timing of nutrient uptake is critically important for sugarbeet root growth, but also for resistance to soil-borne diseases like Fusarium and Rhizoctonia,” says Dr. Huber.

“Any lag in the period when the crop needs manganese and you have reduced yield potential. It’s why you see the yellowing of some crops after an application of glyphosate. It has chelated and immobilized micronutrients in the crop tissues.

“For a while, the crop will be just sitting there in suspended animation from a development standpoint, which impacts yield.”

 

Dr. Westra

The Sysstem-Ready phosphite ions give the zinc and manganese systemic movement through the plant and down into the roots to keep the plant physiology at optimal level.

The benefit of adding the nutrients to glyphosate was demonstrated in 2008 sugarbeet trials conducted by Dr. Philip Westra, professor in the Department of Bioagricultural Sciences and Pest Management at Colorado State University, and by field agronomists of the J.R. Simplot Company, one of the Sysstem-Ready distributors.

The CSU sugarbeet trials showed that with Sysstem-Ready added to the tank mix with glyphosate there was an average 4.5 tons/acre increase in yield. The trials also showed no statistically significant reduction in control of weeds such as green foxtail, pigweed, kochia and barnyard grass.

“I was generally pleased with the nutrient system,” said Dr. Westra. “I thought the crop plants that received Sysstem-Ready with the glyphosate had more color and shine, better root systems and better overall vigor.

“There were a few more leaves, and the leaves were darker green and more shiny. The visual effects are subtle, but important. The plants appeared healthier, and this may be due to the disease resistance that important nutrients like manganese provide. Crops in high alkaline and calcareous soils may be particularly responsive.”

 

Simplot Trials

The average sugarbeet yield increase in four replicates in the Simplot trials also was about 4.5 tons/acre, says Rob Ford, Simplot Grower Solutions field development agronomist in Scottsbluff, Neb.

“Glyphosate-tolerant beets have been very widely adopted, but they need a very sound nutritional program,” says Ford.

“Disease resistance is a highly important aspect of well-timed nutrition. In a prolonged wet, cool spring season nutrition is even more important for fending off disease. There were a few reports of Rhizoctonia and curly top in glyphosate-tolerant fields, sometimes occurring where these diseases were not a problem in prior years.”

Dr. Huber notes that research conducted at Colorado State University has shown that glyphosate can increase susceptibility of tolerant sugarbeets to Rhizoctonia and other diseases, so proper nutrition to minimize the potential damage from these pathogens is especially important in the new glyphosate-tolerant beets.

Ford said better plant health was apparent in the Sysstem-Ready plots. “Where we treated with Sysstem-Ready the leaves were healthy and there were no lesions, and in the fall. The treated beets were still vibrant when the untreated beets were starting to dry down and finish.

“We could have waited another three weeks to harvest the plots and seen an even bigger increase in sugar content of the treated beets, but the harvest schedule was dictated by the untreated beets so we could have a good comparison.”

 

Replication

Ford said the replicated plots were conducted in cooperation with local growers and results were based on a 10-foot-of-row comparison.

“This year we will have a much larger mix of replicated trials. The Simplot company is very interested in how to optimize use of these nutrients,” says Ford.

“In addition to the application with glyphosate, we’d like to test giving the beets two shots of Sysstem-Ready zinc and manganese early and in some trials then come back with a third treatment when they do the potash application, or perhaps late enough to try Sysstem-Ready with boron. Three applications of Sysstem-Ready is a reasonable program in beets.

“We’ll pull several tissue samples at various timings during the season, and we look forward to some interesting results coming out of the field studies.

“But based on the results from 2008, we believe it’s important for growers to try these glyphosate compatible micronutrients in their fields this year. If we have another really tough spring, it will be a great opportunity for Sysstem-Ready to make a difference. The way I look at it, if you can see a symptom of nutrient deficiency, you’ve already lost more money than the treatment will cost you. So it’s better to head off deficiencies.”

The Sysstem-Ready technology also is available in calcium, magnesium and potassium formulations providing these essential plant nutrients. Each is compatible with the other. 

Sysstem-Ready is a real problem-solver for growers who want to maximize production of glyphosate-tolerant crops, says Ken Dart, national sales manager of Minneapolis-based Agro-K Corporation, which developed the phosphite-linked nutrient system.

“A one-pass nutrient-plus glyphosate application also helps growers avoid delays due to adverse weather, unnecessary costs for energy, wear and tear on equipment, and soil compaction,” says Dart. “Sysstem-Ready also can be an effective tool to maximize yields in conventional crop varieties and hybrids.

“With Sysstem-Ready, zinc and manganese are rapidly transported to the developing roots and foliage when and where they are most needed during peak demand,” Dart says. “We recommend Sysstem-Ready sugarbeet treatments when the plants are about four or five inches tall or with the first glyphosate application, followed by another treatment of Sysstem-Ready with the later glyphosate application, which often is with 0-0-20 potash as well. With or without glyphosate, Sysstem-Ready effectively enhances plant development and yield potential.”

“Cyst nematode is present in the Idaho soils; it is a parasite on sugarbeets and can really cause problems,” says Dennis Searle, Senior Agriculturalist for Amalgamated.

“Dr. Saad Hafez has been trying for years to teach us that we need to be planting oil radish and mustard varieties that do not increase cyst populations. Some do. So the practice is good but the choice is less random than one thinks. One needs to make sure the variety used has been screened by Dr. Hafez and will not increase cyst nematode populations.”

The following information is provided by Dr. Hafez, Mike Thornton, Dave Barton, Brian Finnigan, Gale Harding and Mir Seyedbagheri. It is based on studies at the Parma Research and Extension Center.

The information from the studies indicate that certain cultivars provide better suppression of cyst nematodes than do other cultivars (Table 1). In general, radish crops provide slightly better suppression than do mustard crops.

A major concern in growing radish and mustard green manure crops is the relatively long growth period required to produce an acceptable amount of plant biomass. It takes 8 to 10 weeks of at least 60 degrees F soil temperature to get satisfactory plant growth and cyst nematode suppression. Frost is also a concern because it will kill the plants if the temperature drops below 28 degrees F for mustards, or 25 degrees F for oil radishes. Early plantings generally produce more plant biomass, provided frost damage is avoided (Table 2).

For fall planting, the last week of July to the second week of August is the optimum planting date in southwest Idaho. For spring planting, the first two weeks in March are recommended in southwest Idaho. Planting dates in other regions should be adjusted according to local soil and air temperature conditions, and danger of a killing frost.

The complete report can be found on the University of Idaho College of Agriculture website, www.uiweb.uidaho.edu/sugarbeet.