Kristen Obeid, OMAFRA Weed Management Specialist – Horticulture
As the rains continue to delay planting this spring, weeds are beginning to germinate and are getting a head start. But … this may not be a bad thing. It is the perfect opportunity for growers to set up a stale seedbed, particularly horticulture growers that do not have a wide choice of herbicides to use in their crops.
The stale seedbed technique is an old method to enhance weed control in seeded crops. It was developed by farmers years ago, even before herbicides were available. This technique works best for later seeded crops but may be adapted to many systems. A stale seedbed is created by tilling the soil early which encourages the weeds to germinate. In most springs, this means a tillage in April, with a good flush of weeds by mid-May. However, this year we are seeing some fields already covered with weeds even without the early tillage. The weeds are then killed with an herbicide without disturbing the soil. This is accomplished by using herbicides like glyphosate or Ignite, or by non-chemical means like flamers or mowing very close to the ground. The key is to NOT disturb the soil, so that weed seeds remain buried. The crop is then seeded or planted with minimal soil disturbance. In many cases, growers find that weeds only sprout in the small area disturbed around the seed or transplant.
If you are lucky, a new flush of weeds will emerge before the crop. Repeating the burndown herbicide or flaming just before the crop emerges will enhance the level of weed control. In many cases, two burndowns will control weeds through the critical period of weed control for most crops.
Soil applied herbicides can also be used pre-emergence or post-transplant where registered.