I have seen cankers on Norway Maples a few times in our area of southern Delaware. The bark seems to split open and some sap flow is evident. I looked at one yesterday that had dozens of these infected areas. Any help would be appreciated. I realize norways are looked at as weed trees in many areas.

I also have seen serious cankers on red oak trunks from the ground up to 10 feet or so. These cankers cause the trunk to swell in size and become distorted in shape. A dark substance is sometimes flowing from the affected area.

Thank You,
Dan Nelson
C.A. PD-0186

Reply to post by Dan Nelson, on October 13, 1999 at 12:55:45:

Hi Dan,

2 cents worth,

Perhaps some of these trees have 'wetwood' or 'slime flux'. Smell the affected area of the tree(s) if possible and see if there is an odor of any kind?. How do the tops of these trees look?
Lyons and Sinclair (Diseases of Trees and Shrubs) mention that there are no controls for wetwood, but for slim flux, installing tubing into the tree to
drain the liquid away from the trunk can improve
appearance. It maybe just cosmetic.

Kim

Reply to post by Kim, on October 13, 1999 at 12:55:45:

I am currently investigating a similar problem for a client who has planted A platanoides "Emerald Queen" on a boulevard. One year later and the bond is up for release, but the city is asking for replacement of many trees because they have cracks and slime flux. Most of these cracks are vertical (the others are handling / installation issues)and have in some case opened up. In most cases the callus tissue is well defined and healthy. Where thebrak has not yet cleanly split a slime flux is ooxing out. The contractor tells me that he thinks they are "frost cracks" and that they were present in the nursery.

I am not so sure, and wonder if this is not a cultural condition bought on by nursery practices, or by the stress of transplanting from the nursery to the site.

One person tells me that Shigo believs it to be nursery pruning practices. Any comments or thoughts out in the ether?

Cheers

Julian Dunster

Reply to post by Julian Dunster, on October 13, 1999 at 20:19:47:

Iv'e done some autopsies of trees ive dropped that have basal cracks, many stem from injuries from when the plant was very young. And as Shigo said the wont crack every year. They close over and rerupture frm time to time.

Maybe that is what youll need to do, destructive QC so to speak. Tho this would not rule out damage from harvest in the nursery, you may be able to show it was from field maitinance or such.

Reply to post by Kim, on October 13, 1999 at 12:55:45:

And Shigo sais that you break the bearier and greatly decrease the compartmentalization potential of the plant incraesing the failur potential.

Reply to post by Dan Nelson, on October 13, 1999 at 12:55:45:

Dan, If there is a good pathogen around, then any injury can cause canker infection on a susceptible host. For N. maple, the pathogens include Nectria, probably Phytophthora (even above-ground) and many others. The initial injury might be sunburn, pruning damage, prolonged moisture plus heat, even growth-induced splitting of a thin bark when it is growing vigorously (my opinions). Freezing, dessication, gaffs. Sapsucker. Staking wounds. Insect borers and bark beetles. Good luck.