Common Conditions That Promote Certain Weeds

Webster defines weed as a plant that is out of place. In a corn field grass and clover are weeds; in a hay field volunteer corn or a small grain are weeds, in turf crabgrass and foxtail maybe the weeds. In most cases some type of a plant protection chemical is used to get rid of the weed. Sometimes this is only a temporary cure to improve the situation, after the effects of the treatment where off and the problem returns.

Dr. Sid Bosworth, University of Vermont, did some work and found that there are other factors that contribute to certain species of weed growth. Dr. Bosworth work is summarized in the following table.

Weed

Conditions

Algae

Excessive surface moisture

Annual Bluegrass

Excessive surface moisture, compaction, mower too low, high nitrogen

Barnyardgrass

Poor drainage

Birdsfoot Trefoil

Droughty conditions, low nitrogen

Black Medic

Droughty conditions, low nitrogen

Broadleaf Plantain

High pH, compaction

Buttercups

Poor drainage

Chickweeds

Mower too low

Cinquefoil Species

Droughty conditions, excessive surface moisture, low pH, general low fertility

Clover Species

Low nitrogen

Coltsfoot

Poor drainage, low pH

Common Chickweed

Too shady

Common Mullein

Low pH, general low fertility

Corn Chamomile

Poor drainage, high pH

Corn Speedwell

Compaction

Crabgrass

Droughty conditions

Creeping Bentgrass

Poor drainage, excessive surface moisture, mowed too low

Creeping Speedwell

Too shady

Creeping Thyme

High pH

Curl Dock

Droughty conditions

Docks

Poor drainage, low pH

English Daisy

Low pH

Foxtail Species

General low fertility

Goosegrass

Droughty conditions, compaction

Hawkweeds

Low pH, general low fertility

Henbit

General low fertility

Hop Clover

High pH

Knawel

Low pH

Lady's Thumb

Poor drainage, low pH

Leafy Spurge

Doughty conditions

Mallow

General low fertility

Moss

Excessive soil moisture, mowed too low, too shady

Mouse-ear Chickweed

Too shady

Nutsedge

Poor drainage

Pigweed

Droughty conditions

Pineapple Weed

Compaction

Plantains

Poor drainage, mowed too low

Prostrate Knotweed

Compaction

Prostrate Spurge

Droughty conditions, compaction

Rabbit Foot Clover

Droughty conditions, low pH, high pH

Sheep or Red Sorrel

Low pH

Speedwell

Droughty conditions, mowed too low

Vetch Species

Low nitrogen

Wild Carrot

High pH, general low fertility

Wild Parsnip

General low fertility

Wild Radish

General low fertility

Wild Strawberry

Low pH

Yarrow

Droughty conditions

Yellow Woodsorrel

Droughty conditions

Source: Bosworth, Sid. 1998. Using Plants as Indicators for Diagnosing Soil and Turf Problems. Turf Notes, Vol. 7, No. 2, p. 1-5. New England Extension Systems, Un. of Massachusetts Extension.

While there maybe other factors involved other than the ones listed, these are some general guidelines and conditions that can occur and be corrected relatively easily and inexpensively.