I saw the very first Dandelion in flower yesterday on a lawn. Surrounding it, were Daisies enjoying the spring sunshine. Spring arrives early this year. While March 21st is traditionally the first day of spring, the astronomical event that marks the turn of the seasons – the Vernal Equinox – occurs at 11.44 on Friday the 20th March.
As their name suggests, the two equinoxes of spring and autumn are the points when day and night are of equal length – at least north or south of the equator, where light and dark are a lways in balance.
Everything starts to gather speed now. The grass is finally colouring up and putting on its' spring growth spurt and the weeds are coming out of their winter slumber.
If you have a lot of weeds that have over wintered, now is the time to think about selective weed control application. You normally get two periods of weed activity in a normal year. The broadleaf weeds such as Cat's Ear, Plantains, Daisies, Dandelions to name a view of them will easily over winter in the turf. These need to be killed early on before the second turf weed season starts when you get the Red, White Clovers, Yellow Suckling Clovers and Trefoils appearing in around May time.
I was asked over the weekend by a neighbour why selective herbicides kill weeds and not the grass. I told him that the biologial make up of weeds and grasses is different. The weeds, like trees and shrubs have Cambium Cells. These cells provide support in the main trunk and branches of the tree or weed. The selective weed killer is a growth hormone that mimics the actual growth hormone 'Gibberelline' - the plant hormone responsible for secondary thickening. The selective turf herbicide is absorbed by the weeds and after a while, the weeds go into super growth, with their stems twisting and distorting. The weeds actually outgrow themselves and when their overall structure has literally had it, they die. Grasses do not have Cambium Cells so although they might absorb some of the chemical, it has no affect - if applied correctly in the first place!
One of the other early flowering turf weeds is Slender Speedwell, which exhibits tiny blue flowers. It is a challenge to kill it and early application of a selective herbicide is advisable. Once it has finished flowering, control is said to be too late.
If you are a lawn owner and need advice please visit our Lawn Blog and a Professional Turf Manager, please Email the Weed Free Team for some advice or service.
Comments