(Texas)
Fertilizer trials in Texas have provided some of best examples of leaf rust (Puccinia recondita) suppression from Cl in the Great Plains. Leaf rust is perennially a major threat to winter wheat and limits the area of viable production in this region. In the winter wheat trial below NH4Cl was topdressed on two dates, i.e. mid-September (Fall-preplant) and early-March (Spring). Leaf rust infestations at this site were particularly severe due to the abundance of winter rain (> 20"). The results illustrate that in high moisture environments spring topdress Cl applications are more effective in suppressing leaf rust (see photograph) and increasing yield than preplant-Fall applications. With abundant winter rain, fall applied Cl may become positionally unavailable to the plant due to leaching losses below the crop rooting zone. This is evident from the plant tissue Cl levels and explains the different response to the Fall vs. Spring applied Cl at this site.
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| Leaf rust infestation in winter wheat (cv. Pioneer 2158 ) flag leaves at anthesis as affected by timing of NH4Cl application (40 lbs Cl/a). Bosque Co., May 5, 1992. |
Agronomic results from this study
| Table 3. Yield and test weight of Pioneer 2158 winter wheat as affected by timing of NH4Cl application (40 lbs Cl/a). Bosque Co., 1992. | |||
| Parameter | Fall Cl | Spring Cl | Control (0 Cl) |
| Yield (bu/a) | 59.6a# | 68.3b | 54.3a |
| Test w (lbs/bu) | 58.0b | 60.0c | 56.0a |
| Plant Cl (%)¶ | 0.28a | 0.73b | 0.29a |
¶ Plant Cl determined on whole samples colleted at anthesis (i.e. May 5, 1992). # Within row means followed by the same letter are not significantly different (P=.05). |
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