Hello, Yoon -- re your comments re local loss of goldenrod and alfalfa 
fields -- just pick the right stuff.

Here in south Louisiana, the major spring flow is the immigrant Chinese 
tallow tree or (farther north) the imported hedge plant, privet.  Both are 
considered aggressive pests by non-beekeepers, like your midwestern 
knotweed.  But trees are hard to eradicate (tallow); so are big shrubs 
(privet).  No problems yet from non-beeks..

Walter Weller

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