Winter Wheat Performance Following Seed Treatment in South Central Kansas

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Procedure
Field experiments were initiated in the fall of 1986 and continued through the summer of 1989. Sites were located at Kansas State University's South Central Ex-perimentField, near Hutchinson, !{Sand on a cooperating farm west of Caldwell, KS. A randomized block design with a split-plot treatment arrangement and five replications was used at both locations in all years. Six hard red winter wheat cultivars (Arkan,Hawk,Larned,Mustang,Newton,and TAM 107) were utilized in the main plots. Foundation quality seed of the six cultivars was treated in the Wilbur-Ellis Seed Laboratory, Fresno, CA. Fungicides were uniformly applied at the rates given in Tables 1, 2, and 3 using a Hege II laboratory seed treater. Untreated foundation seed from the same lots as the treated seed was used as a control. The seeds were drilled at a depth of approximately 1 in . on 7-in. centers at a rate of 60 lbs per acre in 1.75-ft by 15-ft subplots. Plots were seeded in early to mid-October each year. Emergence was evaluated by counting the number of live emerged plants per 9 ft of row (three 3-ft sections of row in the center of each subplot) approximately 3 wk after planting. Grain yield and moisture percentage data were collected by harvesting a 1. 75-ft by 13-ft area of each subplot. Grain yields we:· ) converted to bu/ ac at 12.5 % moisture. The data fo, emergence and grain yield were analyzed using split plot analysis of variance procedures to determine if any significant (P = 0 .05) interactions existed among seed treatments and cultivars.

Results and Discussion
The analysis showed significant differences in both emergence and yield among cultivars (data not presented) but revealed no significant interactions between seed treatments (fungicides) and cultivar. Therefore, comparisons of emergence and yield were averaged over all cultivars to determine the effects of fungicide. Emergence and grain yield by seed treatment varied considerably by year and location.
In 1986-87, treating the seed with fungicides did not affect emergence significantly (P = 0.05) compared to the control, except for Nusan 30EC at the high rate (Table 1). This treatment significantly reduced the number of plants at both locations. The number of plants per acre ranged from 492,000 to 502,000 at Hutchinson and from 470,000 to 497,000 at Caldwell. The lower rate of emergence at Caldwell was attributed to the slightly wetter soil conditions at seeding. Differences in grain yield between locations were evident. Grain yields were approximately 10 bu/ acre less within a treat-( Only one fungicide treatment of seed had a significant effect on emergence in 1987-88, i.e., Nusan plus the high rate of Baytan (Table 2) . However, a trend toward reduced emergence with treated seed compared to the control began to develop. Emergence ranges were wider than in the previous year. At Hutchinson, a range of 798,000 to 879,000 plants per acre was ob- served. Stands at Caldwell, as in the previous year, had lower emergence figures, with a range of 744,000 to 820,000 plants per acre. When compared with the control, only one significant reduction in grain yield occurred, i.e., the Nusan 30EC treatment at Hutchinson. In 1988-89, the trend for reduced emergence with treated seed continued to express itself (Table 3). However, as in previous years, treating the seed with fungicides resulted in no statistically significant reducti.on in stand. Under less than ideal conditions for emergence (dry soil), ranges were much narrower and differences in emergence between locations were less than in. previous years. This indicates that the effects of seedapplied fungicides on emergence are greater under moist soil conditions. Grain yields at Hutchinson were considerably lower than in previous years and, for the first time during the study, fell below those at Caldwell. A sudden drop in temperature (from 82 °F on February 1 to :-20°F on February 2, 1989) had a more severe effect on plants at Hutchinson than at Caldwell.

Conclusions
The results of this study indicate that fungicide treatment of seed of dry land winter wheat planted in the south central region of the Great Plains does not significantly affect the number of seeds that germinate and produce viable (emerged) plants. No consistent effect of seed treatment on grain yield was observed. Treatments that reduced stand did not result in reduced yield, and reduced yields occurred where there were no reductions in stand.
Because all the tested cultivars responded similarly to the fungicide treatments, limited precautions probably are necessary in treating seed from cultivars with the same genetic background.