Re: Re: Re: Re: Dwarf mistletoe
nphc@icehouse.net
Wed, 13 Jan 1999 21:45:10 -0600 (CST)
Florel is labeled for applications to ornamental conifers for the reduction of dwarf mistletoe. However it is tricky business in terms of timing and causing interior neddle drop especially with Douglas Fir. Read the label for sure. Certainly Florel alone(without pruning)would only be marginally effective and would almost definitely require repeat applications.
Although mistletoe is somewhat of a drain on the trees reserves it is not like other insect or disease problems which actually cause death of plant parts(i.e.Diplodia,Anthracnose,stem cankers). These pests and many more are considerably more damaging to a tree than would be dwarf mistletoe because the trees source for the production of its enrgy reserves is being compromised or eliminated.
As for tree mortality associated with dwarf mistletoe it would be a slow death at best. If death would result following an infection it could be 30 or more years before the tree would succumb and most likely there would be other contributing factors.
The resulting "brooms" associated with heavily infested branches are actually unique to say the least. Unpleasant or unaesthetic to some and to others these brooms can actually have ornamental value.
If the infection is light(confined to the lower limbs), these can be pruned out with relative success in controlling the population. If the plant is growing from bark fissures on the trunk or is located throughout the crown, control is probably not feasible.
My concern as an arborist when approaching a heavily infested tree is the weight associated with the heavy "brooms". If these limbs have a target, they should be at least lightened. Also, the mechanical injury that would take place if one of these lower larger limbs were to break at the branch collar could be signifigant. The ripping of the socket exposing heartwood on the trunk could condemn the tree as a hazard. A little preventative thinning of the broom could alleviate this and at the same time increase the ornamental value.