It is not easy to go through a Gulf Coast growing season without seeing
some problems on many plants. Determining the problem requires skill, facts,
and careful progression from one part of the diagnosis to another. Any
time you are unsure of your diagnosis, before treating please consult with
one of our Cornelius Texas Certified Nursery Professionals.
Diagnosing your own problems
Perceive the problem correctly and entirely. Is the problem actually
just a natural stage of growth for your plant, like fern spores or leaf
pores? Are you looking at your plant or at some other organism, like an
insect or a speck of dirt?
Consider things that can cause abnormal plant growth. The following
tables list non-parasitic (environmental) and parasitic causes for plant
damage.
PLANT DAMAGE FROM
NON-PARASITIC CAUSES
Water
Soil Moisture-Too much water causes the roots to rot and the
tops to die. Let plants dry out more thoroughly between watering.
Too little water causes the entire plant to wilt, but is easily
corrected by watering.
Irregular watering can stress your plants and leads to decline.
A constant and adequate water supply is the best remedy.
Low Humidity-A dry home atmosphere can cause brown tips and
leaf-drop. Misting occasionally can help overcome this problem. Tropical
plants grown outside often exhibit the same symptoms. Periodic spraying
of the foliage with clear water will help correct this. Also, try moving
the plant into more shade.
Light
Insufficient Light-Characterized by spindly, weak growth, lack
of blooming, or failure to break dormancy. Move plants, if possible, to
a brighter area, or increase the available light. Artificial lighting on
indoor plants is remedial, and pruning light-obscuring growth corrects
your problem outdoors.
Excess Light-Too much sun can cause loss of chlorophyll, characterized
by bleached foliage and possibly black spots. Additional shade helps solve
this problem.
Nutritional Disorders
Discoloration in leaves having a definite pattern is often nutritional.
Symptoms are usually above ground.
Nutritional excesses can be overcome by leaching the soil with
the addition of ample amounts of water.
Deficiency diseases. Consult the Key to Plant-Nutrient Deficiency
Symptoms Information Sheet to help you in your diagnosis. The addition
of a well-balanced plant fertilizer will correct symptoms of underfertilized
plants.
Temperature
Low temperature effects-Several warm-weather plant species are
damaged by non-freezing low temperatures. Injury includes browning of leaves,
dieback of shoots, or killing of the entire plant.
Freezing injury appears papery and bleached. Container plants
may suffer unseen root damage only. Symptoms often appear later once growth
has resumed and a secondary organism has entered.
Hot weather causes stunting of some spring-planted annuals and
winter grasses. Leaf tips and edges brown and rapid wilting occurs.
Fluctuating temperatures-A wide fluctuation of temperature is
responsible for such problems as bud drop in camellias and tomatoes. When
temperatures do not fluctuate enough, we have springs where peach and plum
trees do not bloom well. Dormancy has not been satisfied.
Atmospheric Impurities
Salt Accumulation-This affects container planting more often,
but can occur in the landscape. It normally results from over-fertilization
or more commonly from lack of drainage. Pots should have a hole in the
bottom and planting beds should be elevated. Lack of drainage keeps the
soil super-saturated and lacking in oxygen. Even more salt is left behind
after the water evaporates, often causing tip and marginal leaf burn. Fluorine,
often present in municipal water supplies, causes marginal leaf burn in
many plants.
Air Pollution-Man-made pollutants cause many problems. Damage
appears as yellowing and eventual browning of foliage.
Ozone occurs naturally and also causes plant damage such as
stippling, flecking, and mottling of foliage.
Ethylene gas occurs naturally from ripening fruit and damaged
plant leaves. It causes leaf and flower drop and poor floral development.
Toxicants-Weed killers-Most often the result of spray drift
from nearby areas. This can affect the leaves, stems, flowers and roots.
Little or no remedy is available for this problem. Often weed killers are
residual in the soil for a specified period of time. One must wait to replant
until the herbicide has dissipated.
Excess insecticides or fungicides. Usually caused from failure
to follow manufacturer's directions for particular plant with particular
problem.
Mechanical Injury-Dead or broken limbs and "barked" trunks are
often due to tractors, cultivators, or weed-trimmers. Only above ground
parts should show symptoms. If this is found, clean and seal the wound
with pruning paint.
Animals-Mice and rabbits usually chew plant parts above the
ground (you may see teeth marks). Gophers and moles usually tunnel below
ground and eat root parts. Armadillos can damage both above and below ground
plant parts. Dogs and cats also cause damage from urinating in the same
place over a period of time. With observation, you should be able to find
proper repellants for the animals in question.
PLANT DAMAGE FROM PARASITIC CAUSES
Diseases-These usually affect leaves, roots, stems and trunk.
They are caused by fungi, bacteria and viruses. Control is best with appropriate
fungicides, algaecides or bactericides designed for the specific problems.
Insects-These chew holes or suck plant sap from leaves, stems,
trunk and roots. Appropriate insecticides will control most insects.
Nematodes-Microscopic worms that cause "disease-like" symptoms.
They are located in the soil and feed on roots, as well as above ground
and feed on stem, leaves, and flowers. Few nematicides are available over
the counter, so consult with our Texas Certified Nursery Professional.
Next, begin a close observation of the affected plants. Symptoms tell you there is a problem. You must define and see the problem correctly in the beginning. A simple 10-power (10x) hand lens is very helpful.
1. Examine leaves closely. Using the lens will help to detect mites.
2. Gather more data. Examine the trunk and , if necessary, the roots.
3. Compare the unhealthy plant with a healthy one.
4. Question the background of the affected plant for any of the non-parasitic
clues listed above.
You can also find some valuable information on pot plants in our selection of garden books available on sale at any of our garden centers.
Important Note: keep your thinking orderly and do not let one or two striking symptoms lead you to the wrong conclusion. Always work with sets of symptoms.
The following table will give some clues to the types of problems you
will encounter:
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