Burnett: Fight off invading crab grass without chemicals
By now, if you have this in your lawn you have become well aware of it.
You don’t see it in the spring or even early summer, but as the summer progresses it begins to become visible—a low lying seedy grass which takes on a purplish hue as fall approaches.
This common turf grass weed is called Digitaria sanguinalis, commonly known as crab grass.
Quite often the name is confused with quack grass, but the two are quite different.
Unlike quack grass, crab grass is an annual. In other words it germinates in the late spring, grows all summer then dies in the late fall leaving its seeds behind to carry on the following spring.
Crab grass originated in the Mediterranean and North Africa and was brought to North America by settlers in the mid-19th century as a forage crop, although I can’t for the life of me understand why.
Perhaps it was because it will survive under drought conditions, however, for whatever reason it has become a real nuisance as a turf grass weed.
As well, it has invaded all parts of Canada in gardens and landscape beds and naturalized in meadows and ditches in the countryside.
Because of its places of origin, crabgrass thrives in hot dry climates such as the Okanagan.
Up until recently, the control of this pesky weed was quite simple because of a couple of chemicals that used to be available.
There was a pre-emergence product that when applied in the spring prevented the seeds from germinating. There was also a product that would control young seedlings in July.
Both these products have been removed from the market, so we have to get control of crabgrass by beating it at its own game.
Here is what you do. Because crab grass only grows in hot sunny conditions it will not germinate if the turf grass is on the long side and thick.
At this time of the year, remove as much as possible the adult grass along with the seed.
Apply a good top dressing of Natures Gold and sand 50/50. Sow some good quality grass seed and apply a start-up fertilizer.
In spring, the new grass should be growing well so keep nurturing the areas with a good quality spring fertilizer and let the grass grow a little longer than you normally would.
Any crab grass seed left at the base of the new turf grass will not germinate. Of course, you will have some that comes anyway even after all this effort so this will have to be repeated at least a couple of years and maybe more.
If you stick with this program, eventually the crab grass will be under control with only a small amount appearing which can be easily pulled out and discarded.
But you will always have to keep an eye out for it because the seed can survive in the ground for three or four years.