3.1.9
WIDESPREAD AND COMMON WHEAT AND BARLEY DISEASES INDUCED BY SOILCOPPER DEFICIENCY INTERACTIONS

IR EVANS, DC PENNEY, E SOLBERG and GW WOLFF

Alberta Agriculture, Food and Rural Development, 6903-116 St, Edmonton, Alberta, Canada, T6H 4P2

Background and objectives
Low yields, lodging and shrivelled grain in wheat and barley, as well as melanosis in wheat and delayed maturity in barley, were identified as important crop production problems in Alberta in the 1970s. In addition, wheat and barley were observed to perform very poorly on organic soils. In the early 1980s, barley yield trials on organic soils showed remarkable responses to soil and foliar applied copper. In the following years, Piening et al. [1] were able to demonstrate control of melanosis in wheat, with high yield increases in both barley and wheat, from soil-applied copper on a sandy loam site where copper levels were approximately 0.2 ppm (DTPA). Subsequently, Penney et al. [2] were able to demonstrate similarly spectacular responses in Dark Grey Chernozem soils with 0.6 ppm (DTPA) extractable Cu.

The objectives of this study were to determine the effects of copper deficiency on ergot, melanosis and crop lodging, with particular attention to yield and grain quality of wheat and barley.

Materials and methods
In order to determine the amount and extent of copper deficiency for both wheat and barley crops, trials were set up at numerous sites in Alberta where melanosis was known to be prevalent in wheat, and with confirmed deficient soil copper levels. Replicated complete block trials were used in each case. High levels of Cu application were applied to selected treatments as CuSO4 to cause immediate availability of copper, since this element is relatively immobile in soil. This work has continued over the past 10 years, with a wide range of additional parameters being monitored.

Results and conclusions
The results of these trials were impressive, the most noteworthy being phenomenal increases in yield and quality, and significant reduction of ergot infections. Drawing from internationally published research results, processes and mechanisms for the observed reduced resistance to ergot and melanosis, and the increased frequency of lodging due to copper deficiency are suggested. Yields of wheat were observed to triple at some sites, and ergot infection levels were reduced five-fold. Yields of barley frequently increased by 60%, and crop maturity was observed to occur 10-14 days earlier than control treatments.

It has been found that herbicides, livestock manure, crop residues, wet springs, high soil organic matter levels, high pH, and sandy soils can all interact with low or deficient soil copper levels to induce or facilitate a wide range of diseases in these cereal crops. Disease symptoms in barley and wheat, such as ergot infection, melanosis, pigtailing, simulated frost injury, flag leaf chlorosis, excessive tillering, lodging, delayed maturity, trapped awns, shrivelled or empty grains, and major reductions of yield and quality, all correlated with soil copper deficiency, have now been well documented in Alberta. Of the approximately 10 million cultivated hectares in this province, soil copper levels may be deficient in 20% or more, since the DTPA detectable levels in these soils range from 0.2-0.9 ppm Cu.

References
1. Piening LJ, MacPherson DJ, Malhi SS, 1987. Canadian Journal of Plant Science 67, 1089-1091.
2. Penney DC, Solberg ED, Evans, IR, Piening, LJ, 1988. Proceedings Great Plains Soil Fertility Workshop 2, 172-179.