Managing for high yield

A review of intensive wheat production research in North Dakota in 2004

Compiled by Joel Ransom
joel.ransom@ndsu.nodak.edu

Experiments were conducted by North Dakota State University during the 2004 growing season with the objective of identifying practices that could be used to improve the productivity of wheat in North Dakota.  These experiments varied somewhat in the factors that were studied but included one or more of the following: seeding rate, N rate, N timing, variety, and fungicide. 

The intent of this report is to summarize the effect of selected management practices in a range of experiments so that farmers may have a better understanding of how these practices may impact production on their own farms.

A similar report was prepared in 2003 and the results of that report should also be reviewed when considering the results and recommendations presented here (the 2003 report is available online at: www.ag.ndsu.nodak.edu/aginfo/smgrains/IntensW04.htm).

Table 1 lists the experiments that were included in this review and the contact details of the principal investigators from whom additional information about the research can be obtained.

The experiments were designed so that the effects of each factor could be evaluated as well as the interactions between the various factors.  Positive interactions between management practices are considered desirable, as it means that the output of two or more inputs is greater than the output of each input alone. Just as in 2003, however, there were few significant and consistent interactions between the various main factors, so this report will focus primarily on main factor responses. The cool, wet spring in the areas where this research was conducted was favorable for small grain development, and yields were well above average. 

Seeding rate
Increasing the seed rate from the lowest rate used (1.0 to 1.2 million seeds per acre) to the highest rate (1.5 to 2.0 million seeds per acre) increased yields in three of the five experiments (Table 2). The increases were only in the range of 2 to 3 bu/acre, however. In two of the five experiments, increasing the seed rate reduced yield. 

Nitrogen rate and timing
The effect of nitrogen rate and timing on grain yield and protein varied between experiments. Nevertheless, in general terms, the results indicate that when fertilizer rate was included as a variable in the experiment, applying all of the fertilizer pre-plant at the high rate was as effective as and often more effective than applying it in splits (Table 3). 

At the lower fertilizer levels, or in experiments where just one level of N was used, grain yields were improved by splitting the fertilizer only in Carrington and Langdon. Grain protein tended to be higher when N was applied later but not consistently.

Fungicide
Only a single fungicide experiment at Carrington was included in this review.  In this experiment, the fungicide treatment consisted of a single Folicur application at the early bloom stage. There was significant fungicide interaction by variety at this site. Reeder was much more responsive to the Folicur application than Granger (18 bu/acre vs. 8 bu/acre), due to its greater susceptibility to foliar diseases and leaf rust.  The DON levels were higher in Reeder than in Granger, and were reduced significantly in both varieties with the application of Folicur.

Conclusions and recommendations
Based on the results of these experiments and the data from 2003 (bear in mind that 2003 and 2004 were exceptional years for wheat yield), I would recommend the following:

• There seems to be only marginal value in increasing seeding rates beyond 1.2 million seeds/acre (perhaps somewhat higher for durum).  Avoid over-seeding and use the money saved for other inputs that will likely produce greater returns (i.e. nitrogen or fungicide).
• Based on a reasonable yield goal, apply all nitrogen before planting.  If during the early development of the crop, however, it appears that the yield goal will be exceeded, apply extra nitrogen using streamer bars.  Applications on or before the 6 leaf stage are recommended in order to improve yield as well as protein.
• A fungicide applied at heading has the potential of increasing yields by protecting the flag leaf from foliar disease even in years and regions of the state where FHB pressure is low.  Consider applying fungicides in years that are conducive to the build up of diseases, especially if a variety that is known to be susceptible to foliar diseases is grown.

Table 1. Wheat management experiments conducted in North Dakota in 2004

Location Management factors studied Principal Investigator Casselton & Carrington1 Seeding rate, variety, N rate, N timing Brian Otteson Brian.otteson@ndsu.edu Mohamed Mergoum mohamedmergoum@ndsu.edu Carrington2   Seeding rate, variety, fungicide Greg Endres reg.endres@ndsu.edu Blaine Schatz Blaine.schatz@ndsu.edu Langdon N rate and N timing John Lukach john.lukach@ndsu.edu Minot Seeding rate, N timing, fungicide (durum and HRSW) Kent McKay kent.mckay@ndsu.edu

Table 2. Effect of seeding rate on wheat yield in ND, 2004

Location Seeding Rates (seeds/ac.) Yield (bu/ac.)+ Casselton 1.2 million 88.9**   1.7 million 92.0 Carrington1 1.2 million 94.4N.S.   1.7 million 94.0 Carrington2 1.0 million 71.9*   1.75 million 69.8 Minot – HRS 1.2 million 49.6N.S.   2.0 million 51.6 Minot – durum 1.0 million 44.7N.S.   1.5 million 46.8

+ N.S. means that there is no statistically significant difference between the values within an experiment, *, ** means there are statistically significance differences at the 5% and 1% level, respectively.

Carrington¹: evaluated seeding rate, variety, N rate, N timing

Carrington²: evaluated seeding rate, variety, fungicide

Table 3. Effect of N timing on wheat yield in various experiments in ND, 2004

Location N Timing Yield (bu/ac.) * Protein (%) Casselton 125 lb PPI 92.9** 14.0*   63 lb PPI, 63  lb 5 lf 87.5 14.4   42 lb PPI, 42  lb 5 lf, 42 lb boot stage 83.9 14.8   200 lb PPI 96.5 14.8   100 lb PPI, 100 lb 5 lf 92.3 15.1   67 lb PPI, 67 lb 5 lf, 67 lb boot 89.7 15.2   LSD 0.05   2.8   0.2 Carrington1 150 lb PPI 94.8** 13.4* (irrigated) 75 lb PPI, 75 lb 5 leaf stage 96.5 13.2   50 lb PPI, 50 lb 5 lf, 50 lb boot stage 83.7 15.3   250 lb PPI 99.2 15.0   125 lb PPI, 125 lb 5 leaf stage 99.6 14.6   83 lb PPI, 83 lb 5 lf, 83 lb boot stage 91.4 15.9   LSD 0.05   8.0   0.2 Langdon 170 lb PPI 60.4* 14.0*   80 lb PPI, 90 lb 3 lf 58.1 14.2   80 lb PPI, 90 lb 6 lf 66.0 13.6   80 lb PPI, 45 lb 3 lf, 45 6 lf 65.0 13.8   LSD 0.05   6.1   0.8 Minot (HRS) 85 lb PPI 50.0* 12.9*   40 lb PPI, 45 lb 5 lf 50.6 12.9   85 lb 3 lf 48.7 12.3   85 lb 5 lf 48.1 12.5   135 lb PPI 53.3 14.1   85 lb PPI, 50 lb 5 lf 51.9 13.6   85 lb, 50 lbs flag 50.5 13.5   LSD 0.05   2.8   0.5 Minot 85 lb PPI 47.5N.S. 14.3N.S. (Durum) 40 lb PPI, 45 lb 2 lf 44.8 13.9   85 lb 2 lf 44.1 13.7   90 lb 5 lf 46.7 13.9

Table 4. Effect of applying Folicur at flowering on wheat yield in various experiments in ND, 2004

Location Variety by Fungicide Treatments Yield (bu/acre) DON (%) Carrington2 Granger, Folicur 79.2** 1.2*   Granger, no Folicur 71.2 2.7   Reeder, Folicur 74.4 2.4   Reeder, no Folicur 55.8 4.4   LSD 0.05   4.6 0.9

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Treat Seed to Control Loose Smut

Loose smut, has been an increasing problem on wheat and barley in Minnesota, according to Charla Hollingsworth, University of Minnesota extension plant pathologist, Crookston. 

The disease is promoted by cool temperatures (60s to low 70s) when plants are at the flowering stage, and our last two growing seasons have been cooler than normal.  The fungus infects plants during flowering and colonizes the developing kernels where it remains dormant until the seed germinates. When the plant begins to grow, the pathogen grows as well.  In most cases, entire heads are covered with fungal spores when they emerge at heading. Hollingsworth recommends that seed from infected fields should have a systemic seed treatment to help prevent the disease.

Loose smut in a field near Crookston.  Photo: Charla Hollingsworth, U of M extension plant pathologist.