What would you think if you saw your neighbor plowing his fields in the dark while wearing a pair of night-vision goggles?
Crazy?
Maybe not, say some weed specialists.
Recent attention has been given to the practice of night cultivation as a way to deter weed growth.
The idea is based on the fact that light in the red spectrum, known as the phytochrome system, assists the germination of many weeds.
Most crop seeds, on the other hand, will germinate in darkness.
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Ordinary daylight cultivation briefly exposes weed seeds to light before they are reburied.
This brief exposure, which could be as short as a millisecond, can often be enough to stimulate weed seeds to germinate.
Studies have found that nighttime tillage significantly decreases weed densities.
Work done by United States Department of Agriculture research scientist Doug Buhler indicated that tilling soil in darkness can reduce the presence of small-seeded broadleaf weeds by 50 to 80 percent.
Reductions ranged from 70 percent for common lambsquarters to less than 30 percent for Pennsylvania smartweed.
Another study reported that weed cover in intensively cultivated land in Germany was reduced from 80 percent to two percent if cultivation was carried out during darkness.
This type of “photo control” is not without its problems.
Some weeds produce seeds that don’t require red light to germinate. There are also the issues of safety and the practicality of operating in total darkness.
Understanding the dormancy requirements of weed seeds provides a new approach to managing weeds and offers potential, but it is not a complete solution to weed problems.
