Inputs for Wheat Production: What’s Economic, What’s Not?

Results in 2003 and 2004 show that economic return from some inputs used for spring wheat production must be based on decisions made during the growing season – there’s no substitute for good scouting.

Compiled by George Rehm, U of M extension soil scientist in cooperation with Russ Severson and Char Hollingsworth, U of M Crookston

The importance of various inputs for producing hard red spring wheat has been well-defined, and economic returns have been calculated. However, there is less certainty about the economic importance of various combinations of production inputs. Growers are annually faced with decisions about what combination of inputs to use. This demonstration project was designed to document the economic impact of several management strategies on production of hard red spring wheat.

This study was conducted in 2003 and 2004 at the Northwest Research and Outreach Center in Polk County, and the fields of cooperating wheat producers. The additive importance of individual inputs to overall management strategies was evaluated at each site on Oxen spring wheat. There were seven different management strategies or treatments that were replicated four times at each location.

Management strategies selectively included the following individual inputs.

1. Increased seed to achieve a population of 1.25 million live seed per acre instead of 80 lb. per acre
2. Vitavax Extra RTU seed treatment applied at a rate of 5 ounces per 100 lbs. of seed
3. Tilt (2 oz. per acre) in combination with herbicide at the 3-5 leaf stage
4. Tilt (2 oz. per acre) plus Pencap-M (1 qrt. per acre) at flag leaf
5. Folicur (4 oz. per acre) plus 20 lb. N per acre (10 gallons of 20-0-0-3) at early-flowering.

Two treatments were used as standards or controls from which the remaining five treatments were compared. For example, all of the above production inputs were included in treatment #1, whereas none of the production inputs were included in treatment #7.

There is general agreement that fertilizer and herbicides are essential for optimum yields. Therefore, all sites were fertilized according to University of Minnesota guidelines. Likewise, commonly used herbicides to control broadleaf weeds and foxtails were used at all sites. The seven treatments tested in this study are summarized in Table 1.

Table 1: Description of production strategies/treatments used in the input study.

Treatment #	Add’l Seed	Herbicide + Fungicide 3-5 lf	Fungicide + Insecticide, flag lf	N & Folicur	Seed Treatment
1	yes	Yes	yes	yes	yes
2	no	Yes	yes	yes	yes
3	yes	Yes	yes	yes	no
4	yes	No	yes	yes	yes
5	yes	Yes	no	yes	yes
6	yes	Yes	yes	no	yes
7	no	No	no	no	no

In the 2004 evaluation, Oxen spring wheat was planted in late April into wheat residue in Polk County, into soybean residue in Red Lake County, and into barley residue in Otter Tail County.

Oxen is known to be susceptible to leaf spot diseases as well as scab. After plants headed, eight randomly selected stems per plot were rated for leaf disease severity based on the percentage of leaf area with disease. Twenty-five heads were collected from each plot at soft dough to be rated for Fusarium head blight (FHB, scab) incidence (the number of heads with at least one infected spikelet) and severity (the number of diseased spikelets on each head). Grain yields were measured at maturity and samples were analyzed for protein as well as vomitoxin (DON) levels.

Results
Results in Polk and Otter Tail Counties -- As in 2003, excellent yields were measured again in 2004 (Table 2). The effect of treatments was consistent at both test sites. Specifically, yields were lower without the combination of Folicur and liquid N (treatment #6) and in the absence of any tested inputs (treatment #7). The omission of other single inputs (treatments #1 – 5) had no substantial negative effects on yield. Relative to increased yield, individual inputs such as added seed, seed treatment, fungicide for control of leaf diseases at the 3-5 leaf stage, and the combination of insecticide and fungicide at the flag leaf stage did not boost yield at either test location.

Table 2. Yield of Oxen spring wheat as affected by the use of various inputs.

------------------------Location and Year------------------------ Treatment   Polk Co. 2004 Otter Tail Co. 2004 Red Lake Co. 2004 E. Polk Co. 2003   ------------------------------bu. per acre------------------------------ 1 96.7 82.8 118.8 90.8 2 92.8 80.8 119.7 93.3 3 93.9 82.8 122.7 98.5 4 93.7 83.0 118.8 95.4 5 93.7 83.5 119.3 94.4 6 86.4 76.6 117.0 95.4 7 82.2 72.0 110.6 94.2

However, quality of wheat grain continues to be an important issue for Minnesota growers. Differences in treatments significantly affected quality. Leaf spot diseases such as tan spot, septoria leaf and glume blotch, and leaf rust were present at both locations. The Otter Tail site also had widespread and severe bacterial stripe and to a lesser extent, stripe rust. Fungicides do not control bacterial stripe, so it spread readily across plots and treatments. Plots in the Otter Tail County test that received treatments #4 (no herbicide or fungicide applied at the 3-5 leaf stage) and #7 (no tested inputs) had plants with significantly more diseased leaf tissues compared to the other treatments (Figure 1). There were no significant differences in leaf disease pressures between treatments at the Polk County test site.

Vomitoxin (DON) levels in grain, produced by the scab fungus, were comparable in both locations (Figure 2). The Polk County site had slightly more DON than the Otter Tail site, which may have been due to the amount of wheat residue on the soil surface which served as a source of in-field inoculum. Treatments #6 (no Folicur or insecticide at heading) and #7 (no tested inputs) resulted in significantly increased DON levels compared to the other five treatments (treatments #1-5) at both sites.

Results in Red Lake County -- Leaf disease pressure was light at this site early in the growing season but increased rapidly after plants started to mature (Figure 1). The usual fungal diseases were present such as tan spot, septoria leaf and glume blotch, and leaf and stripe rusts. Septoria leaf and glume blotch were more severe at this site than the other test locations. The disease remains somewhat of a mystery, but apparently waits until plants are either close to heading, or headed, before producing symptoms. Disease leaf symptoms were sufficiently controlled when at least one fungicide application was made at, or prior to, the flag leaf stage.

Treatment #7 resulted in significantly increased leaf disease symptoms, which may have contributed to lighter thousand-kernel weights (TKW. Treatment #1 TKW was 37.83 grams; treatment #7 TKW 35.01 grams).

Scab disease pressure was light at the Red Lake County site. DON levels were low across all treatments, indicating Fusarium species inoculum was not present (planted into soybean residue) and the environment did not promote disease development. Grain yields held steady even when Folicur was not applied (treatment #6).

Grain samples collected at harvest were also analyzed for protein and the results are summarized in Table 3. Considering the high yields, grain protein was higher than expected. None of the inputs had a substantial effect on grain protein at the Red Lake County site. For the Polk and Otter Tail County sites, protein percentages were lower when the Folicur with N was not used. The reduction was about 0.6% and 0.4% at the Polk and Otter Tail County sites, respectively.

Table 3. Grain Protein of ‘Oxen’ spring wheat as affected by the use of various inputs.

------------------------Location------------------------ Treatment # Polk County Red Lake County Otter Tail County   ------------------------------% Protein------------------------------ 1 13.9 14.7 14.4 2 13.7 14.7 14.4 3 13.8 14.7 14.5 4 13.9 14.8 14.3 5 14.1 14.8 14.4 6 13.6 14.9 14.1 7 13.3 14.7 14.1

Recommendations
The results from this study stress the differences that can exist between growing wheat strictly for yield versus for yield and quality. Inputs such as the use of Folicur at early-heading can be important to both yield and quality of wheat grain in certain years. Producers are urged to avoid planting small grains into small grain residue, to scout fields for disease problems, and to go to the wheat disease web site to determine if the weather supports disease development http://mawg.cropdisease.com, www.ag.ndsu.nodak.edu/cropdisease.

The need for inputs such as insecticides and fungicides vary from year to year. Decisions about the use of these inputs should be based on current information, rather than planning or scheduling applications strictly by plant growth stage.

There was no return from using a higher seeding rate, seed treatment, and fungicides to control leaf diseases and scab if pathogens were not present. When the problems were present (2004 growing season), the economic return was positive.

The results of this project conducted in high yield environments in 2003 and 2004 show that economic return from some inputs used for spring wheat production must be based on decisions made during the growing season – there’s no substitute for good scouting.

Economic Comparison: Economic calculations of the seven management strategies, based on grain yield alone*

Treatment #1: Addl Seed; Seed treatment; Herb + fung 3-5 lf; Fung + insecticide flag lf; N & Folicur Yield increase 6.1 8.2 10.8 Gross return 22.57 30.34 39.96 Input cost 44.66 44.66 44.66 Net return (-22.09) (-14.32) (-4.70)

Treatment #2: Seed treatment; Herb + fung 3-5 lf; Fung + insecticide flag lf; N & Folicur Yield increase 10.6 9.1 8.8 Gross return 39.22 33.67 32.56 Input cost 43.66 43.66 43.66 Net return (-4.44) (-9.99) (-11.10) Treatment #3: Addl Seed; Herb + fung 3-5 lf; Fung + insecticide flag lf; N & Folicur Yield increase 11.7 12.1 10.8 Gross return 43.29 44.77 39.96 Input cost 42.39 42.39 42.39 Net return +0.90 +2.38 (-2.43)

Treatment #4: Addl Seed; Seed treatment; Fung + insecticide flag lf; N & Folicur Yield increase 11.5 8.2 11.0 Gross return 42.55 30.34 40.70 Input cost 40.02 40.02 40.02 Net return +2.53 (-9.68) +0.68 Treatment #5: Addl Seed; Seed treatment; Herb + fung 3-5 lf; N & Folicur Yield increase 11.5 8.7 11.5 Gross return 42.55 32.19 42.55 Input cost 28.52 28.52 28.52 Net return +14.03 +3.67 +14.03

Treatment #6: Addl Seed; Seed treatment; Herb + fung 3-5 lf; Fung + insecticide flag lf Yield increase 4.2 6.4 4.6 Gross return 15.54 23.68 17.02 Input cost 24.05 24.05 24.05 Net return (-8.51) (-0.37) (-7.03) Treatment #7: No addl production inputs   0.00 0.00 0.00

* Always consider grain quality factors in economic analyses when determining
whether management strategies are successful.

This research funded in part by the Minnesota Wheat Checkoff.  For more reports and updates of research funded in part by the Minnesota Wheat Checkoff, go online to www.smallgrains.org/2004WRP/2004wrp.htm.