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Old 06-15-2012, 09:12 AM
Starbuy Starbuy is offline
LawnSite Senior Member
Join Date: Dec 2011
Location: Summit County, Ohio
Posts: 335
Researchers are reporting that Imprelis treated areas are started to show signs of disease now that the plants have been damaged. The trees effected, but not dead are now more susceptible to diseases. I feel so bad for those who've already approved DuPont's resolution offer. I spoke with one last night and they are just trusting that all their plants that have not yet been killed will be covered by DuPont and that after the agreed upon 2 year maximum coverage that their trees will not be damaged by the weakening that is now occuring.

Penn State Extension: "Imprelis Damage Continues in 2012"

Symptoms that I observed this morning include:
Continued leaf distortion on honey locust, pin oak, Japanese maple, and redbud
Fasciation of maple shoots
Terminal bud mortality on oaks and maples
Stem dieback on honeylocust
Witches brooming on oaks
Thin canopies (oaks and redbuds) (Oak trees have been treated preventatively for
anthracnose by an arborist)
Abnormally high production of acorns on red oaks in treated areas, little acorn production in red oaks at other sites on property
Abnormal growth and development of shoots. Terminal growth stunted, lateral shoots elongated
Norway Spruce, needle regeneration at the base of dead shoots. (Approximately 12-18" below the dead shoots)
Dieback on terminal growth of deciduous trees
Longitudinal cracks on red oak trunks which are shaded by the house to prevent south-side bark splitting
Leaf distortion in viburnums and Japanese cherry

Also, one turf professional informed me this afternoon that witches brooming is reportedly being seen by turf companies at sites treated with Imprelis in 2011. I will try to verify this as I visit other sites.

Thomas Ford
Extension Educator

Witch's broom is a disease or deformity in a woody plant, typically a tree, where the natural structure of the plant is changed. A dense mass of shoots grows from a single point, with the resulting structure resembling a broom or a bird's nest.

One example of this would be cytokinin, a phytohormone, interfering with an auxin-regulated bud. Usually auxin would keep the secondary, tertiary, and so on apexes from growing too much, but cytokinin releases them from this control, causing these apexes to grow into witch's brooms.

Witch's broom growths last for many years.
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