root rot in Douglas fir and Lawson cypress

[Roy A. Fletcher]

I'm trying to locate a site that discussed the detrimental effects of heavy watering of tree trunks in irrigated areas. In a public park in my town, we have had 22 Lawson cypress and 12 Douglas firs die due to root rot (Phytophthora and Phellinus weirrii are the identified pathogens). All of these trees have had their trunks at ground level thoroughly soaked because they sit in the middle of irrigated ornamental planting areas or lawns. Their roots are also thoroughly soaked as often as once a week. Any help on locating the lost site would be much appreciated.

Regards. RAF

[Pam - gardengal]

Not sure what site in specific you are referring to, but there are many that discuss root rots occurring as the result of over-irrigating - this is probably the number one cause of fatalities in mature trees, not, as many folks think, drought. Established conifers, specially those which are summer drought tolerant natives of the west coast such as Doug fir and Lawson cypress, need NO supplemental irrigation and automatic sprinkler systems, like those in public parks, need to be zoned very carefully so as not to overwater. And I'm sure you can encounter equally as many sites that will address crown root rots from either excessive mulching around trunks or the situation you describe.

Both of these are pretty commonly known situations by anyone with a horticultural background, certainly at least someone in your parks department - were you looking for the site for documentation of the problem or just curiosity?

pam - gardengal

[Roy A. Fletcher]

Pam - gardengal ( [e-mail]) wrote: with editing... : Not sure what site in specific you are referring to, but there are many that : discuss root rots occurring as the result of over-irrigating - this is : probably the number one cause of fatalities in mature trees, not, as many : folks think, drought. Established conifers, specially those which are : summer drought tolerant natives of the west coast such as Doug fir and : Lawson cypress, need NO supplemental irrigation and automatic sprinkler : systems, like those in public parks, need to be zoned very carefully so as : not to overwater. And I'm sure you can encounter equally as many sites that : will address crown root rots from either excessive mulching around trunks or : the situation you describe.

: Both of these are pretty commonly known situations by anyone with a : horticultural background, certainly at least someone in your parks : department - were you looking for the site for documentation of the problem : or just curiosity?

Yes, documentation. I found a site that discussed the very specific situation we have in our parks, where above-ground sprinklers spray water onto the trunks of mature trees and keep at least one metre of the trunk wet for three months of the summer. But it has disappeared from my links. As for seeking help from the horticulturists in the parks dept., they can't get rid of the conifers fast enough. Given half a chance, they'd have a faller's convention in our municipal parks, and have their pick-ups lined up for the firewood.

Regards. RAF