Q. I live in Denver, CO,
and just planted a Spring Snow Crabapple tree last week. Since 3 days ago, the
tips of the leaves turned a darker green, and overnight turned brown. I am
really hoping this isn’t fire blight. I don’t see any shepard’s hooks or oozing
on trunk. Could it be lack of water? Transplant shock?
 |
| This Asian Pear came down with fireblight which was obvious by September. Asian Pear is very susceptible to fireblight in general. This tree came from the production nursery already infected. Doesn’t happen very often, very small percentage, but it does happen even with the best orchards. |
A. In your climate late
summer and fall is a nice time to plant trees. Temperatures are in the upper
70’s during the day and dipping into the upper 40’s at night. So soil
temperatures are probably in the low 60’s; warm enough for good root growth and
establishment yet air temperatures are cool enough to slow the loss of water
from the leaves.
summer and fall is a nice time to plant trees. Temperatures are in the upper
70’s during the day and dipping into the upper 40’s at night. So soil
temperatures are probably in the low 60’s; warm enough for good root growth and
establishment yet air temperatures are cool enough to slow the loss of water
from the leaves.
 |
| This is a classic picture of fireblight I took showing the shepherds hook, small dead fruit and dieback in the limb. You can’t see it but there is even the bacterial ooze there that you could see glistening off sunlight. This happens 3 or 4 months into the season and when the disease is spreading fullbore. |
Fireblight would infect trees in the spring and the
symptoms usually appear in early summer. It is possible to transport this
disease to a healthy tree through pruning a sick tree and then pruning a
healthy tree without sanitizing the shears. But I doubt that is what is
happening.
symptoms usually appear in early summer. It is possible to transport this
disease to a healthy tree through pruning a sick tree and then pruning a
healthy tree without sanitizing the shears. But I doubt that is what is
happening.
 |
| Even though most infection occurs at the time plants are in flower, the disease doesn’t usually appear until a couple of months later occurring in the new growth or collapse of the flowers that were infected. It is very very possible to spread this disease through pruning from tree to tree and within the same tree. |
It is most likely how it was planted. Maybe the roots got
too dry before it received water or it was planted with dry soil surrounding
the roots. Always soak the soil around the roots with water from a hose a few
times before turning it it over to an automatic irrigation system.
too dry before it received water or it was planted with dry soil surrounding
the roots. Always soak the soil around the roots with water from a hose a few
times before turning it it over to an automatic irrigation system.
Some basic rules to
follow:
follow:
1. Make sure the hole is
at least three times the diameter of the container. If the soil is really bad,
make it 5 times.
at least three times the diameter of the container. If the soil is really bad,
make it 5 times.
2. Make sure water can
drain from the hole in half a day or less
drain from the hole in half a day or less
3. Get the hole sopping
wet before planting
wet before planting
4. Amend the soil put back
in the hole with compost or other good soil amendment
in the hole with compost or other good soil amendment
5. Make sure this soil is
wet immediately after you shovel it into the planting hole. Put water in the hole
with a hose at the same time you are planting
wet immediately after you shovel it into the planting hole. Put water in the hole
with a hose at the same time you are planting
5. Stake the tree after
planting so roots don’t move during strong winds
planting so roots don’t move during strong winds
6. Build a basin or moat
around the tree to capture water from a hose
around the tree to capture water from a hose
7. Water the plant twice,
immediately after you plant it
immediately after you plant it
8. Water it with a hose
every other day for the first week to settle the soil around the roots.
every other day for the first week to settle the soil around the roots.
9. Water once a week after planting with enough water to thoroughly wet
the soil around the roots to a depth of 18 to 24 inches.