Monday, April 23, 2012

Weeds – Identify and Manage

Know the Enemy 

The weeds are numerous.  The weeds grow most everywhere.  The weeds are like unwelcome houseguests that don’t know they stayed too long!

Weeds find weaknesses in the landscape – poor soil is an open invitation. Poor soil is hungry for nutrients.  Weeds don’t care.  Poor soil is dry and rocky.  Weeds don’t care.  Poor soil is in need of vegetation.  Weeds don’t care if they have good neighbors. They are quite able to adapt to less than perfect conditions. 

images (1)

Weeds are classified into three groups – annuals, perennials, and biennials.
Annual weeds include crabgrass and foxtail.  These grow from seed in the spring, mature, produce seed, and die at the first frost in autumn. 
crabgrass in lawn foxtail
Lawns and gardens that are in need of good management are just asking for these intruders.

Biennial weeds include Musk Thistle and Burdock. This is the rosette of year one.
Musk thistle Burdock
Biennials need two years to mature.  The first year they grow these rosettes above and store energy.  The second year they use that energy and flower and produce seeds.  At frost, they die.

This is the flower of Musk thistle, and Burdock. 
Musk_Thistle bloom Burdock flowers

Perennial weeds include many familiar varieties.  Dandelion, Bindweed and Canada thistle are just some of them.
field-bindweed  thistle
Bindweed and thistle spread by horizontal roots and are difficult to control.  If the plant is pulled, some of the root may remain.  This root will continue to grow and will grow a plant from each end, thus doubling your weed problem.
thistle roots

Using an herbicide is the best remedy for control.  The organic option of horticultural vinegar (20%), Acetic acid, clove oil or soap based herbicides will all weaken the plant and eventually cause the plants death if used repeatedly before the plant forms seed heads.

Lawn weeds are classified as broadleaf weeds and grassy weeds.  Some of the broadleaf weeds include plantains, white clover, and dandelions.
clover plantainn

Clover indicates poor nitrogen in the soil.  Fertilize the lawn with Nitrogen, (the first element of the N-P-K) on the fertilizer label.

Plantains thrive in over-watered areas with compacted soil.  Reduced watering and core-aeration will improve the conditions and reduce plantain.
core aeration
Core aeration

A good management of lawns is always to fertilize, water deeply, and mow high.

Grassy weeds are particularly difficult.  Annual grasses like crabgrass and goosegrass  can be controlled by using preemergents.  By applying preemergents before seeds germinate in the spring, seeds will not take hold and stop the cycle for annual grasses. 

Nimblewill is a warm season grassy weed that I have.  The control is difficult because there are few specific herbicides for these type of grasses.  A non-selective herbicide will kill anything that the herbicide is used on.
Nimblewill2 (1) 

Quack grass is a cool season grass and spreads rapidly by underground rhizomes. 
quack grass
Again, spot treating with an organic herbicide is recommended.  When the grassy weeds die from the herbicide application, a bare spot will be apparent.  And unless these bare spots are planted with a desirable grass seed, weeds will eagerly jump in to fill in the spot. 
chickweed2 Chickweed
Chickweed is an annual weed that spreads quickly.  Hand pull or scrape away with a spade.  Aerate and fertilize lawns to discourage its growth.

nutgrass roots spread
Nutgrass is not a grass per se, but a sedge.  Specific herbicides for nut sedge will control this weed in the lawn.  Horticultural molasses, an organic product, also has good results. 
pictures_lawn_weeds_buckhorn_plantain_03 Buckhorn plantain
As a perennial weed, plantain can easily be removed by loosening the soil down the tap root with a dandelion weeder or flat head screwdriver.

pictures_lawn_weeds_carpetweed_01 Carpetweed
The annual weed, Carpetweed  can be controlled with a pre-emergent.  Carpetweed is commonly found in newly seeded lawns or in thin turf. A broadleaf weed herbicide can be used as a post emergent. I would use the organic herbicide with a clove or soap base.

purslane Purslane
Control Purslane by hand weeding.  Cover vacated area with mulch.

protrate spurge Prostrate spurge
Prostate spurge, also known as spotted spurge, likes hot, sunny, dry areas.  Since this weed has a tap root (one long root downward) hand pulling can be ineffectual. Preemergents in spring can reduce seeds from germinating.  Weak lawns allow this spurge to take hold.  Fertilize and water to maintain a healthy, full turf.

Horticultural vinegar works well on this weed too.
Weeds are going to appear in any landscape. Taking a less than panicked attitude to weeds may reduce our knee-jerk approach to grabbing the strong, chemical herbicides. Acceptance of a ‘few’ weeds will go a long way to reduce harmful chemicals in the landscape.

Mulch 2 – 3” thick on flower beds will keep light from weed seeds, and reduce the number of seeds that germinate. Mulches can be pine, cedar, hardwood chips, grass clippings, leaves or straw. Even thick layers of newspaper can serve as a mulch. 

Weeds in the lawn may be more difficult to control, but a good maintenance program will limit their infestation. Mow grass high, don’t scalp the blades and don’t remove more than 1/3 of the blade at any cutting.  The high turf will shade weed seeds and keep soil moist.  Regular organic fertilizer applications can keep the lawn thick and healthy.

 healthy lawn
May the road rise up to greet you, and the weeds stay far away.  Enjoy your lawn and garden, relax……and have a great day!


Gaia Gardener: said...

Traditionally, clover was mixed in with grass seed as a natural source of nitrogen to help keep the grass healthy. It wasn't classified as a weed until the chemical industry couldn't figure out a way to use chemical herbicides on a lawn without killing the clover (since it is a broadleaf plant).

Sunray Gardens said...

Do you know I was weeding each of the winter months. Just not cold enough to kill off anything. Have weeds I've never seen before. I see one is that burdock, all over the place. It's awful and my grass is pathetic. Good luck on yours.

Cher Sunray Gardens

HolleyGarden said...

I have been weeding out bindweed for the past few years. I have just now decided I'm going to have to use a herbicide on it. :(

Ann, aka Amateur Bot-ann-ist said...

Just looking at all of those weeds is making my skin a bit itchy!

Kimberly said...

Great photos of weeds, it's amazing just how many different types there are. Living next to a forest always poses a problem with weeds blowing in and planting themselves somewhere in our yard. Weed killer and yanking them out here and there is our method. Mulching helps but they still come up uninvited! Happy Spring!

Anne Dornay said...

Fantastic info about weeds. Thanks so much.

Prasenjit Saha said...

Thanks for putting up such a nice post. it is very informative.