Seed & Chemical
Managing crops with variable growth stages
By Alberta Agriculture and Forestry
Aug. 24, 2015 - The environmental conditions in 2015 have resulted in many fields having two or more growth stages present. Proper management of these fields will help ensure an efficient harvest.
"Many areas of the province have been subject to adverse growing conditions in 2015," says Mark Cutts, crop specialist with Alberta Agriculture and Forestry, Ag-Info Centre, Stettler. "Crops were subject to many stresses including poor soil moisture conditions, cool soil temperatures and frost. As a result of these adverse conditions, many crops have at least two crop stages present. Fields with variable growth stages will have areas with mature plants, while other areas of the field will be immature. Having variable growth stages complicates decisions regarding timing of harvest operations."
As harvest approaches, Cutts says producers will need to consider their options for managing these fields.
"The main management options available for dealing with variable stage crops include swathing the crop or using herbicides (e.g. glyphosate or a crop desiccant). Regardless of the approach used it should be recognized that managing variable growth stages typically requires the growth of the less mature portions of the field to be terminated. As a result, these areas of the field will not contribute to yield. The advantage of these approaches is the elimination of the variable crop stages and improved harvest management."
One approach that producers could use is the application of glyphosate to a standing crop. Applying glyphosate to a standing crop is commonly referred to as a "pre-harvest application" and is primarily done to control perennial weeds. Glyphosate is a systemic herbicide that moves through the foliage into the plants root system and results in death of the plant. As a result of its behaviour in the plant, glyphosate applied to a standing crop will terminate the growth of the crop and over a period of time the entire field will dry down.
Another chemical option for producers is the use of a desiccant. Desiccants are a non-selective contact herbicide that act rapidly and result in the termination of the above ground growth of crops and weeds. This allows for a quick dry down of the plant material and an earlier harvest. Desiccants are most commonly used on potatoes and pulse crops. However, desiccants do not provide long-term weed control.
"Swathing the crop can also be an effective management tool for crops with variable growth stages," says Cutts. "For example, if a cereal crop has late developing tillers the crop should be swathed when the original heads are at the correct stage (kernel moisture of 35 per cent or less) and before there is any amount of kernel development in the late tillers. This approach will minimize the risk of having green immature kernels that may impact grain grade."