5.7 Critical Period of Weed Control

Vince describes the idea of different thresholds, where some crops are able to tolerate more of one weed than another.  These thresholds come into play when a farmer is determining whether or not to apply additional weed control measures (and thereby, extra expenses) – weighing the benefits and the disadvantages.  Is it more cost effective to spray or is the crop damage from the weed(s) less than the cost of an added control method?  Many thresholds are related to the number of weeds present in a given area and crop.

Critical Period of Weed Control is a threshold commonly used, which is relative to time from planting date.  Researchers have identified at what point during the growing season weeds can inflict the most damage on a crop’s potential yield.  This crucial point in the growing season is deemed the “Critical Period of Weed Control”.   Be sure you can identify and explain all the lines and labels on the Critical Period of Weed Control graph, and apply the concept to weed management choices throughout the growing season.