Norton focused on two particular trials in his presentation. The 2009 corn trial in Bonita with farm cooperator Doug Dunlap was conducted on a 120-acre center pivot field with high nematode pressure and soil variability.

Preseason nematode estimates determined by 250cc soil samples included: Zone 1 – 400 RKN, Zone 2 – 240 RKN, Zone 3 – 250 RKN, and Zone 4 – 18 RKN. Telone II application rates were either zero or 5 gallons per acre (GPA). Half of the crop circle (60 acres) was treated with 5 GPA and the other half with no nematicide.

“An analysis of the yield and Veris maps indicate the half treated with Telone had a significant yield response – up to 35 more bushels of corn per acre in the Zone 1 areas,” Norton said. “In Zone 1 areas left without Telone there was a significant reduction in yield.”  The response to Telone II applications in Zones 3 and 4 was minimal.

In the 2010 cotton trial in Buckeye at H-4 Farms operated by the Heiden family, the field featured a high nematode history and a proven response to 5 GPA Telone II applications. The goal was to utilize soil texture differences to reduce but not eliminate the Telone II application in finer soil texture areas.

The standard rate of 5 GPA was used but 3 GPA was applied in finer textured soils. Nematode densities were Zone 1 – 100 RKN, Zone 2 – 75 RKN, Zone 3 – 95 RKN, and Zone 4 – 60 RKN.

Response in lint yield to Telone II application in Buckeye was positive in all four soil texture zones for both the 3 and 5 GPA rates.  However, the response dropped significantly in Zone 4 and was slightly over the breakeven point considering all costs and returns. 

Research results on the six trials demonstrated the ability to maximize return on investment (ROI) with variable applications of Telone II by targeting the coarsest texture soils of a given field.

Norton’s ROI figures are based on 75 cent per pound cotton and $70 per acre for a 5 GPA Telone II application.

The Coolidge trial showed a very strong uptick in cotton yield, a more than 120 percent increase in lint yield with an over $400 per acre ROI in Zone 1. Three years of trials in Safford generated a range of $30 per acre to $150 per acre ROI in the sandiest regions of the field (Zone 1).

The Bonita corn trial brought nearly $120 per acre ROI in Zone 1. The Buckeye trial with the variable nematicide applications returned $200 per acre for the 5 GPA and $120 per acre ROI for the three GPA in Zone 1. The return on investment dropped off significantly in the finer soil texture zone (Zone 4) at all locations. In the highly variable soil textured soils of the Safford Valley, negative ROIs were experienced in Zones 3 and 4.

In summary, Norton says consistent yield increases were achieved with Telone II under heavy nematode populations. Veris soil surveys consistently predicted higher yield responses and maximized ROI, especially in Zones 1 and 2.

Trials will continue this year in Bonita, Safford, and Buckeye to further study field areas with low soil texture variability and conduct more detailed sampling with Veris surveys.

For more information, contact Norton at (928) 428-2432 or rnorton@cals.arizona.edu.

cblake@farmpress.com