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Tuesday, March 6, 2012

Winter Weeds on the Attack

A mild winter is a mixed bag.  Homeowners have hopefully enjoyed lower heating bills.  Landscape contractors and arborists continue to work without the threat of freezing temperatures in an effort to get a jump start on the upcoming spring season. 
Since the groundhog in PA made his annual declaration in early February, winter daytime temperatures remain above normal.  Winter weeds such as chickweed, henbit, Bittercress and dandelions have been on a rampage in plantings beds and lawns.  Bittercress continues to make new appearances in the suburban landscape.  Like its fellow noxious broadleaf weeds, gardeners should not ignore its existence in the yard. 
Hairy Bittercress (Cardamine hirsuta) germinates and grows into a basil rosette with small dark segmented foliage.  It has a mounded appearance composed of pinnate leaves with alternate 1-2-3 parts of round to kidney shapes leaflets.  Petioles are prominent and hairy.  Flower stems are erect and smooth sporting little foliage.
Small (2-3mm in diameter) white blooms have four tiny petals.  They are arranged in dense racemes.  (The floral structure is on a smaller scale similar to hyacinth flowers.)  Long and narrow purple seed heads can measure up to l.5 cm to 2 cm in length.  Its fruit are known as “Siliques” and can explosively spread seed as much as 10 feet from the parent plant.  Any contact such as walking, raking, weeding, lawn mowing activates seed dispersal. 
Heavy hairy Bittercress infestations are mainly evident in early spring.  Home gardeners can easily forget about this broadleaf weed’s presence around the landscape during the remainder of the growing season. Control measures require timely post emergent herbicide applications in spring and fall.  This weed’s unique and efficient seed distribution mechanism can NOT be underestimated.  If Bittercress infestations are manageable, mechanical removal is highly recommended before and during flowering.  The same advice is helpful for henbit, chickweed and annual bluegrass control. 
Avid home gardeners are strongly advised to contact your local Cooperative Extension Office to discuss the latest recommendations to curb this aggressive broadleaf weed.  Be vigilant now to avoid later pain. 

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