Yield stability is the key factor wheat producers should evaluate when choosing a wheat variety. But the decision should be based on more than just how well the neighboring farm did or what’s always worked, especially as disease and insect pests adapt and as cropping options change with potential to plant for grazing, grain or both.
“Look at variety trials,” said Robert Duncan, Texas AgriLife Extension wheat specialist, during the Blackland Income Growth (BIG) conference in Waco. “Evaluate varieties over multiple years and at multiple locations.”
He also recommended growers look at any yield limiting factors from any test that could have influenced ranking. Drought conditions and a late freeze, for instance, will skew results on what could otherwise be a good choice.
He said to look at grazing potential if that’s an option for a particular farm. “Also look at pest resistance, both disease and insect.”
He used results from 2009 trials to emphasize the value of looking at several locations. In one hard red winter wheat variety trial location, Art, an AgriPro selection, was the best variety, followed closely by Tam 203, Duster (from Oklahoma State University), APOGT3832, from AgriPro, and Tam 304.
None of the top 10 selections produced yields significantly better than the others, Duncan said.
In tests at another location Duster was tops, followed by OK05526 and APOGT3832. “Look at two or three year’s data,” Duncan said. That helps limit variability from weather and other factors.
He said Terral was tops in one soft red winter wheat trial, followed by USG3295 and GA99137. USG3295 was best at a different location.
Yield remains the most important factor in selecting a wheat variety, but other traits are worth noting and growers should match traits to production conditions on each farm or even from field to field.
He said resistance to leaf rust and stripe rust is a crucial concern for some growers. “Both these diseases are moving targets. We’re dealing with two different pathogens and both are constantly evolving. Resistance may break.”
He said Hessian fly can be troublesome for growers in some locations, too. Symptoms include severe stunting, withered tillers and a reduced number of tillers. He said Duster, Chisholm and Ike varieties have shown resistance.
He said researchers have looked at seed treatments and rotating to a non-host crop to help control Hessian fly. Later planting dates also may help manage the pest. “Avoidance is the best bet."
Duncan said the 2010 crop is off to a good start across most of Texas, but many farmers have been frustrated by wet conditions that have prevented timely topdress nitrogen applications. He recommended that growers determine how much nitrogen they still need to make yield goals. He figures 1.5 pounds of nitrogen for each bushel of yield. A 50-bushel target will require 75 bushels of nitrogen per acre.
“If a grower put 10 pounds on preplant, he still needs 65 pounds to achieve his goal. Test strips can help determine needs. Strips with 40, 80 and 120 pounds of nitrogen each can identify topdress needs. Growers can install these strips in their own fields to optimize nitrogen use and returns. Not all fields will need the same amount.”
He said producers have begun to find aphids in wheat fields. “These pests may bring in barley yellow dwarf virus. Controlling the vectors with an insecticide is usually not the best option, however. We may see reduced populations but we don’t always see significantly higher yields.”
He said leaf rust had begun to show up in early February in some fields. “We have not identified stripe rust yet.” Symptoms of the two may look similar, but can be differentiated. Duncan said leaf rust has dark red, halo-effect spots. Stripe rust is more orange in color and displays a more linear pattern.
Variety resistance is a key control option. “But a variety may be resistant to one disease and not the other. If the selection is susceptible to both, growers know they have to apply a fungicide. But remember, fungicides do not enhance potential yield; they just protect it.”
He said susceptible varieties may be economical to plant, but growers need to be aware of treatment options. “Make sure to protect the fly leaf. That’s where 75 percent of the plant’s energy comes from. Timing fungicide application is critical.”
Headline and Quilt have done well in fungicide tests. “All the fungicide treatments were better than the untreated check.”
He recommends untreated test strips to evaluate control success.