[Arid_gardener] Question: Trees, Mulberry, Leaf Drop, Maricopa County

[Olin Miller]

From
http://cals.arizona.edu/pipermail/arid_gardener/2004-April/000350.html

"If there is a black dusty substance beneath the bark that has cracked, the
problem is a fungus called Sooty Canker. If the fungus has advanced into the
trunk of the tree there is not anything that can be done to save the tree
however if the problem is still in the branches you may be able to stop the
problem by cutting off the affected limbs and applying a bordeau paste made
with bordeau powder and water to the stub. The cut should be made several
inches below the cracked bark. Be sure to disinfect the saw  with a bleach
solution. Also dispose of the wood that you cut off.
The fungal spores are transmitted by wind or rain and enter a tree through a
bark wound, sunburn or pruning cuts. This may explain why there are several
trees in the neighborhood with similiar symptoms.
Trees that have been polarded ( the process of cutting back all branches to
the same point each year ) are very suseptable to Sooty Canker. For this
reason the experts do not recommend polarding a mulberry tree."

See also
http://ag.arizona.edu/maricopa/garden/html/t-tips/diseases/sooty.htm

Olin Miller, Master Gardener Volunteer
U of A Cooperative Extension, Maricopa County AZ
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----- Original Message ----- From: "Jon Peters" <petersjc at earthlink.net>
Sent: Saturday, August 18, 2007 7:22 AM
>I have 5 mature mulberry trees all the same age (15yrs old) on the West 
>side of my NW Phoenix home on a flood irrigate(d every 2 weeks), 1 acre 
>lot.  They are all aligned in a N-S direction, spaced 20 ft apart.  Four of 
>them are very healthy, good canopy.  The northernmost mulberry tree has 
>been dropping 90% of its leaves since spring.  The leaves that remain on 
>the tree are curled, and some are yellow (much like the tree was preparing 
>for Winter.  There are no sap or drippings from the tree.
> 1) What is the cause and remedy?
> 2) If it is a disease, how do i prevent it from infecting the remaining 
> trees?