Question
My neighborhood association wants me to remove two young weeping willow
trees from my back yard for a long list of reasons which include being disease
prone* and having aggressive roots and shouldn't be planted within 140 feet
of a house. I planted them where they have lots of space, but not 140'. I have
always loved willows and I dont want to remove them. They also provide a
visual shield between us and 3 new monster houses.
    I'd like some help in defending the trees. What's the good news about
willows I can present to them?

* "Crown galls, fungal cankers, leaf spots, powdery mildew, root rots and
willow scabs. Host plants for gypsy moths and the larvae can decimate a tree
in days.  Other pests that attack Weeping Willows are aphids, borers,
caterpillars and scale insects. Roots are notorious for clogging French drains,
drainage systems, weeping tiles, septic systems, storm drains and sewer
systems, particularly older."

Answer
Weeping Willow grows best when its roots have a good water supply which is why they are often found beside ponds, lakes and rivers. Open spaces are the best place for them to grow because if they are too close to a house, they may block or break drainage pipes in their search for water. Its not good to plant any type of tree near your septic tank.

They have a spread width of about 35 feet and the roots will spread about 1 1/2 times the branches width. This would be about 35 -40 feet from the tree trunk. The normal recommendation is do not plant within 40 feet of septic lines. The newer septic lines are sealed and will stop roots from getting in. Water pipes and sewer lines are not a problem since they are sealed.

The main problem is dropping of small twigs which is messy at times. It does not have any more insect or disease problems than other trees and all can be treated IF they occur.

As long as the tree has the space to grow and is not over a septic line you should not have a problem.

It is a fairly large crown tree 40-50 feet tall and 35 feet spread and needs room so many yards can not fit a willow into them. The main problem would be the septic lines but beyond that if there is space it is not a problem tree.