|
|
|
Weeds
Volume 57 Number 9 Date 06/07/2012 POISON HEMLOCK - An emerging population of this comparatively new invasive weed has been detected near New Glarus in Green County. Poison hemlock is categorized as "prohibited" under the DNR Chapter NR-40 Invasive Species Rule and may not be transported, transferred or introduced without a permit. Although this species occurs only in a few isolated sites in the state, its status as a prohibited plant means weed scientists believe it is likely to survive and spread, potentially causing significant environmental or economic harm. At current low levels, eradication remains a reasonable control strategy. The plants observed on June 5 were flowering, suggesting that controls should be implemented soon to preclude seed production. THISTLES - Several thistle species are near or at flowering stage in southern Wisconsin. Thistles, as many farmers know, are highly aggressive invaders of pastures and perennial cropping systems. Mechanical removal or herbicide spot applications are both acceptable forms of control, but both methods must be repeated several years in a row to achieve long-term population reduction. Mowing should target plants in the late flowering stage. --Clarissa Hammond, DATCP Weed Scientist 
|
|