Cc: North American Fruit Explorers <nafex@lists.ibiblio.org>
Subject: [NAFEX] Fw: Pear Rust
Date: Fri, 5 Jun 2009 12:17:12 -0500
Jim,
It seems no one else has any thoughts on this subject. So here is what
I do know about it. You may be looking at any of several rusts and only
think it is PCR. CAR grows for a year on cedars which have to be
re-infected annually to keep the disease going. There are two others I
haven't sorted out yet, one makes the same sort of balls on cedars but
smaller. The other, which I think is quince rust, makes lesions on cedar
trunks and branches. This one lasts for years on cedars and can cause
serious damage to the cedar. (oops, translate juniper) I had never noticed
it before but after last year's severe rust on a chestnut crab I discovered
that simply selecting CAR resistant apples is not sufficient. There are so
many species of this sort of cedar- rose family rust that apples, pears,
hawthorns, quince and juneberries all need to be taken into account as well
as the juniper host plants. Most of the infection is on the haw, quince and
juneberry fruits, if you are inspecting them. You'll have to look up
specific symptoms for each to sort them out. On the cedars, wait for rainy
damp weather and inspect for infection. Cut out the little balls and
consider removing at least the worst infected trees. The bad one is the
quince (I think) rust on the cedar trunks. I found one small tree with a
little bitty new infection. A section of trunk about the diameter and
length of my finger was sprouting little orange dots. then I found a tree
with a 2" dbh trunk that had a lesion as long as my arm down the trunk
oozing great wads of orange goo. THEN I found a 6" dbh tree in the woods
with orange goo oozing at the base of the trunk. At least it was low to the
ground and pretty far from any of my fruit trees.
You see how serious this problem can be, which is why we are advised to
eliminate all cedars from our property if we want go grow fruit. For me,
that is impossible. Not only would my husband object VERY strenously, but
there are large junipers right on the edge of the neighboring property that
plainly can drop any spores they like right down on some of my trees. Plus
junipers are a major part of our winter landscape and pleasure that time of
year. So while I was researching the subject with mounting horror last
winter, I discovered that tangled up in my search results were lists of
resistant junipers. Most of the ones tested are older vars that are no
longer trendy in the nursery trade and hard to find. I was lucky that I
called an old TTU prof about the 3 clones of cedars on Tech property and he
told me they were Keetleri (resistant) and Canerti (infested, as was plain
to see). The lovely new clone Gray Owl has proved resistant. And it seems
that junipers are really easy to graft, and different species graft just
fine on our native trees. So though I was late getting started, it appears
I got over 50% takes and learned that the recommended veneer graft is indeed
the best way to graft junipers. I hope to "collect the whole set" by next
Feb even if it requires a trip over the mtns to the Raulston Arboretum where
many the fine juniper clones collected by Raulston are on display. (Oh, I
can just imagine how much suffering such a trip will cause, a terrible rash
of tree envy that will only be mildly assuaged by much more planting and
grafting.)
My idea is to veneer graft near the base of reasonably small cedars on
the property, say 2" or 3" at the base. I'm thinking about spiraling grafts
up the trunk on some of the larger trees. After a year or so I can start
removing the existing tops and with time the larger ungrafted trees.
Instead of impoverishing our winter landscape, I can enhance it with colors
and shapes that citified landscape freaks would die for. And all very
cheaply.
Any of you who think I am silly, make yourself a note to look for newer
plantings of a beautiful low cedar that is brilliant blue gray. And start
looking more closely at junipers in your area this winter. There is so much
variation in form, it's quite interesting. When I went to cut some branches
on the 40 year old Keetleri trees at Tech, the more I looked the more I felt
terrible for cutting anything off at all. Every branch, every branchlet
looked like a whole series of bonsai trees. They were indescribably
beautiful. Fractals, phi ratios, Fibonacci series..... I was utterly
smitten. They look very nice from a distance too. Donna