Wilson
Bros Nursery is OPEN TO THE PUBLIC 7 DAYS A WEEK!
Disease
Control for Plants & Trees
Is
There a Fungus Among Us?
Below are descriptions, images
and remedies for the most
common diseases found on ornamental
plants in Zone
8.
Always
read and follow the instructions
for safe mixing and application
on the label of each fungicide
you use. Pay close attention
to the types of lawns a fungicide
can and can't be used on.
Chlorosis
Symptoms:
Chlorosis is a condition
that may result from
disease, or infestation,
poor growing conditions,
or lack of nutrients
in the soil, and can
be recognized by the
yellowing of foliage
on evergreen shrubs
or trees such as Azaleas,
Camelias, and Hollies.
Solution:
If there is no evidence
of damage from insects,
and the soil is well-drained
than chlorisis is probably
present as a result
of an iron deficiency.
To correct this unsightly
condition you may spray
foliage with an iron
fertilizer such as Miracid
or, for best results,
broadcast Hi-Yield
Iron Plus around
the root system of the
plant. It may also be
beneficial to mulch
around the root system
with an organic product
such as Claycutter
or Mushroom
Compost to
enhance overall health.
Yellowing of foliage
on Junipers could be
an indicator of spidermites.
Shake a branch over
your open palm and look
for the tiny crawling
insects. Read
label to find proper
mixing and application
instructions.
Fire
Blight
Symptoms:
Blossoms
or ends of branches
turn brown, then black,
and then die. Most prevelant
on fruit trees, flowering
fruit trees such as
the Bradford Pear, and
rarely on a few ornamentals
such as cotoneaster.
Catch this disease as
quickly as possible
to inhibit further spread
and possibly death of
the tree.
Solution:
Prune
infected twigs or branches
at least 12" beyond
decay as soon as disease
is noticed and destroy
debris by burning. It
is best to sterlilize
pruners with rubbing
alcohol between each
cut.
Leaf
Gall
Symptoms:
Developing
new leaves and new shoots
are thickened, fleshy,
and enlarged. Diseased
leaves can become up
to 10 times thicker
than normal leaves.
Found mostly on Azaleas
and Camelias.
Solution:
Once
the galls develop, the
best control is to remove
them when they are first
noticed. Search carefully
to remove all galls.
If they are not removed
and destroyed the disease
will be more severe
the next year.
Black
Spot
Symptoms:
Circular
black spots with fringed
margins appear on the
surfaces of leaves in
the spring. The tissue
around the spots or
the entire leaf may
turn yellow, and the
infected leaves may
drop prematurely. During
hot and humid conditions
certain roses are highly
susceptible to black
spot, except for the
Knock
Out roses and a few
others. Some shrubs
and trees are prone
to develop leaf spot.
Solution:
For
Roses spray with a solution
of Fertilome
Liquid Fungicide
at 7-10 day intervals
through hot and humid
weather. Spray other
shrubs such as Azaleas
and Hollies 2 to 3 times
at 2 week intervals.
Black Spot or Leaf Spot
can be brought on by
spraying foliage with
water. We recommend
watering susceptible
plants at the roots.
Remove fallen infected
leaves from under plant.
Mulching once a year
with organic matter
such as Claycutter
or Mushroom
Compost enhances
overall health and disease
resistance. Also consider
fertilizing susceptible
plants with Milorgantite
for enhanced disease
resistance.
Lichen
Symptoms:
Brown,
gray, green, or yellow,
crusty, soft or leaflike
growths develop on trees
and some shrubs, typically
those growing in moist
areas. The growths are
usually found on the
lower or shaded part
of trunks and branches.
Solution:
Algea,
lichens, and mosses
do not harm the plant,
but may be unsightly.
Sometimes these trees
or plants could be under
stress due to the moisture
retentive soil. Control
lichens by pruning away
surrounding vegetation
to increase the amount
of light and air flow,
which will also help
to dry out the soil
around the roots. A
light mulching with
organic matter such
as Claycutter
or Mushroom
Compost to
enhance overall health
can also be very beneficial.
Also
consider fertilizing
susceptible plants with
Milorgantite
for enhanced disease
resistance.
Powdery
Mildew
Symptoms:
Leaves,
flowers, or young stems
are covered with a thin
layer of light grayish-white
powdery material. Infected
leaves may turn yellowish
and drop. Older varieties
of crape myrtles, some
varieties of roses,
and many other plants
and trees are susceptible
to powdery mildew. If
you are planning to
purchase crape myrtles
in the future make sure
to get the Fauriei
hybrid crape myrtles,
which are resistant
to this disease.
Solution:
Spray
with Fertilome
Liquid Fungicide at
10-14 day intervals
until mildew is gone.
Rust
/ Cedar Apple Rust
Symptoms:
Yellow
to brown spots up to
a 1/4" in diameter
appear on the upper
surfaces of the leaves
starting in the spring
or late fall.
Solution:
For Apple Trees - Cedar
Apple Rust cannot be
controlled on this seasons
apples. Next spring,
spray apple trees with
Fruit Tree Spray when
the flower buds turn
pink, again when 75%
of the petals ahve fallen
from the bloosoms, and
once more 10 days later.
When practical do not
plant apple trees within
several hundred yards
of junipers or red cedar.
For
other plants that have
rust: At
first sign of rust pick
off and destroy the
infected leaves and
spray with Fertilome
Liquid Fungicide at
10 to 14 day intervals.
Rake up and destroy
any infected leaves
that have fallen. Prune
off and destroy infected
twigs.
Sooty
Mold
Symptoms:
In
late summer or fall,
crape myrtles and gardenias
may develop a sooty
black substance that
appears on the surface
of leaves and sometimes
the stems .
Solution:
Honeydew
aphids are your problem
here. The aphids come
from the undersides
of leaves at night and
leave a sticky residue
on the surface of leaves.
The black sooty mold
then begins to grow
on the sticky residue.
Spray both the upper
and lower surfaces of
leaves, as well as the
branches with Malathion
to kill aphids.
Shotgun
Disease
Symptoms:
Found
primarily on Otto Luyken
laurels, this condition
looks as though someone
shot the plant with
bird shot from a shotgun.
Leaves will have many
small holes. The condition
is caused by heat and
humidity. Otto Luyken
laurels prefer afternoon
shade.
Solution:
We
know of no cure for
shotgun disease on Otto
Luyken laurels. The
plant will not die from
this condition, however
infected branches can
be pruned away once
heat and humidity have
subsided. Next year
the plants will leaf
out in spring with new
foliage that covers
the previous years damaged
foliage. Also
consider fertilizing
with Milorgantite
for enhanced health
and disease resistance.
Disease
Prevention Tips
Conditions favoring most diseases
on ornamentals are when the weather
is warm and humid, and there is
an over-abundance of rain.
If you have a sprinkler system
make sure not to add to this problem
by running it during these wet
periods. During dry spells run
your sprinkler system during the
early morning hours so that the
sun can dry water off the leaves.
Watering during the late evening
or night time can promote the
onset of damaging funguses..
Maintain plant vigor by following
proper fertilization requirements
for your ornamentals. SEE: Fertilizing
Shrubs & Trees
Keep an eye out for leaves that
develop fungus or disease and
remove the diseased leaves as
soon as possible to inhibit spread.
Remember, many of the diseases
that attack ornamentals can be prevented
by following proper cultural practices,
and fungicides may not be needed.
Again,
Read
and follow the instructions for
safe mixing and application on the
label of each fungicide you use.
Pay close attention to the grasses
a fungicide can and can't be used
on.