
Lawn & Garden
Ornamental
& Tree Diseases
It's a fact -- money
does grow on trees and other plants in the home landscape. Healthy
trees and woody ornamentals add to property value (an average 15 percent,
according to recent research), plus an attractive and well-maintained
landscape beautifies the neighborhood and provides a great place to
relax.
One of the most important
components of a home landscape program is protection of trees and shrubbery
from disease pests. Unfortunately, landscape plants are vulnerable
to attack by a wide range of diseases caused primarily by fungi, bacteria,
viruses, and nematodes, which are referred to as biotic agents of plant
disease.
Most disease-causing
agents are microscopic, which means that homeowners won't see the microorganisms
which cause blights, leaf spots, and other problems on their azaleas,
roses, hollies, oaks, maples, and other plants which are popular in
southern landscapes. Although these pests are small in size, the damage
they cause is often quite visible, and detracts from the beauty of
the home landscape. In some cases, when susceptible plants are planted,
or conditions are favorable for disease development, plants are killed
by diseases.
In addition to the
biotic agents of disease, trees and woody ornamentals are also frequently
affected by non-parasite disorders (abiotic agents of disease), such
as injuries caused to trees during home and driveway construction,
compaction of soil around roots, or poor growing conditions brought
on by extended periods of drought or too wet or cold weather.
As an additional example,
plants such as azaleas, camellias, photinia, hollies, and other popular
woody ornamentals are susceptible to root rot under conditions of poor
drainage in landscape beds. Prolonged exposure of roots to saturated
soils leads to plant death and the expense of plant replacement.
Although landscape
plants are vulnerable to biotic and abiotic agents of disease, this
doesn't mean a healthy landscape isn't possible. Most plant health
problems can be prevented, provided home landscapers become more knowledgeable
of diseases, and recognize that problems can be prevented provided
precautionary steps are taken to prevent parasitic and non-parasitic
disease development.
This web site is intended
as a source of information for anyone who wants to know more about
how to protect the health of their trees and other landscape plants.
Want to know more about a specific topic? If so, let me hear from you!
Frequently
Asked Questions
- What are the circular
raised areas on oak trees?
- I have patches of
crusty greenish-gray growth on the bark of my azaleas, camellias, and
plum trees?
- The leaves on my azaleas
have become thickened and formed whitish, fleshy gall-like growths?
- Okay to mix an insecticide
with my fungicide when spraying roses for black spot?
- One side
of maple tree looks just fine, but the side closest to my driveway
has dead branches and didn't leaf-out this spring?
- Where do I go for
problem solving assistance with sick plants in my landscape?
- What's
wrong with my photinia? The leaves have numerous, circular dark-colored
spots, and now the leaves are dropping.
- Hybrid tea roses
really did great the first year, but I've had constant problems since.
- What's
the powdery stuff on the leaves and flowers of crape myrtles?
- There
are a lot of dead branches and twigs in my Bradford pear trees.
- When should I begin my fungicide application
program this year for diseases on my trees and shrubs?
- Will
a fungicide eradicate existing disease symptoms?
- Why
did the disease symptoms appear to get worse after I sprayed my cherry
laurel with a fungicide for blight control?
- Why
are repeat applications of fungicide necessary?
- Will it be okay to use leftover fungicides and
products next season?
- I've noticed swollen areas, covered with orange
powder, on some of the branches of my loblolly pines.
Is this a disease problem?
- I understand mistletoe
is a parasite. Will it eventually kill my trees?
- Just
what is a slime mold fungus and will it harm my azaleas or
other landscape plants?
- I'm
interested in a make-your-own fungicide called Bordeaux mixture.
- Why are we losing so many of our elm trees?
- I
was disappointed with my spring flowering bulb crop. Any ideas what
went wrong?
- How
about using diseased plant material (prunings of fire blight- infected
branches, rose leaves infected with black spot, and similar materials)
in my compost?
- Unfortunately,
I don't know much about protecting my shade trees and other woody
ornamentals from diseases.
Plant Disease Dispatch sheets
Other
Information
Images
of Ornamental & Tree
Diseases
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