Whitetop or hoary cress

(Cardaria draba)

Family: Brassicaceae

Life Cycle: Perennial

Roots: Rhizomatous with a spreading root system from which many shoots are produced.

Leaves: Alternate with upper leaves that clasp the stem.   They are undulate (wavy margins) and are lance in shape.  Leaves are sparsely pubescent (covered in tiny hairs) with a bluish tinge. 

Stems: Can be as tall as 2 feet

Flowers:  White and clumped and may resemble the look of cauliflower from a distance.

Seeds: Seed pods are heart shaped and one plant can produce upwards of 5000 seeds per year.    

Note:  The spread of whitetop seems to most likely be moved through hay/feed.  Missoula County has very few areas with whitetop, which tend to be centralized around the Frenchtown area.  Once found immediate action must be taken. 

 

Effective control methods:

 

Herbicides such as Escort XP (Metsulfuron Methyl), mixed with 2,4-D, controls whitetop during the early stages of growth to early flower stages.  Waiting until flower to treat is a great tactic because you can see the weeds present but at that time higher chemical rates are needed to receive the same control. 

Cultivation:  In areas with smaller infestations, cultivation has proved to work with intense persistence and consistency.     


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