by BERNARD TOBIN
The yellow spots identified in wheat fields last spring by Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA) cereals specialist Peter Johnson were caused by sulphur deficiency.
Tissue sampling revealed that green, healthier plants in other areas of the field tested much higher for sulphur levels than the yellow plants. The diagnosis was confirmed when Johnson applied sulphur to test strips of yellow plants.
Johnson explains that sulphur deficiency has rarely been seen in wheat, mainly due to the impact of acid rain, which would typically deposit up to 30 pounds of sulphur per acre in the early 1990s, almost double the requirements of a wheat crop. Johnson quips that acid rain “should have been called foliar fertilizer.”