By: Ken Panchuk, PAg, Provincial Specialist Soils
Sulphur is not mobile in plants, so crops need a constant supply of sulphur from shortly after emergence to the completion of seed filling. A shortage at any stage of crop growth can result in reduced yield. When scouting fields, sulphur deficiency symptoms will usually appear in patches, and seldom affect the entire field. If you see sulphur deficiency symptoms appear in patches, take action by broadcasting some ammonium sulphate.
Sulphur deficiency symptoms on the first true leaves of a canola plant can be cupping upward of the leaves and/or yellow spotting. Other symptoms are:
- Cupping upward of the leaves with possible reddening of the underside of the leaf margins;
- Interveinal yellowing of the newest leaves;
- Spindly plants;
- Smaller pale-yellow flowers; and
- Poor pod development with poor seed filling, resulting in delayed maturity.
Research has shown that ammonium sulphate can be applied up to the early flower stage to rescue yield. However, the earlier the application is made, the better the chance of recovering full yield potential. For more information see our sulphur in crop production fact sheet.