It's easy to identify
trees in the landscape that are not thriving. It is far more
difficult to determine why trees are not growing vigorously and
what to do to correct a given situation. Sources of problems
could range from insects, soil conditions, fertilization,
herbicide injury, maintenance practices, diseases or weather
conditions (freezing, excess rainfall, wind damage, sunburn).
Using the wrong control strategy can be time consuming ,
expensive and ineffective. For example, plants with root rot
often exhibit wilting symptoms because of the lack of viable
roots to extract water from the soil. Applying additional water
in response to the wilt symptoms saturates the soil and creates
conditions favorable for further root rot.
An accurate diagnosis of
the situation is critical. Before seeking help, review the
current status of the entire landscape. Have any cultural
practices changed recently or were recently completed
(irrigation, fertilizer, pest control, pruning)? Have weather
conditions followed seasonal norms or is weather in seasonal
transition (e.g. winter to spring)? What is the apparent health
and vigor of neighboring landscapes? Have you seen similar
symptoms in past years? Answering these or similar questions may
help you zero in on the problem or at the very least prepare you
to discuss the situation with a consultant or county agent. The
University of Arizona, College of Agriculture, Cooperative
Extension Service has offices in each Arizona county. They are
usually listed in the Blue Pages of most phone books. The
Cooperative Extension Service offers information by phone and an
array of useful publications dealing with the most commonly
encountered problems. The county office staff are familiar with
common diseases and pests of local landscape trees and can serve
as an authoritative source for control options. Most offices can
send plant or soil samples to laboratories on the Tucson campus
if additional diagnostic work is needed.
Professional, certified
arborist can also be a source of answers for tree care
questions. These professionals generally offer their services
for a fee. If control options include the application of
pesticides it is prudent to confer with a qualified professional
before spraying. Desert adapted and native desert trees have few
insect and disease pests.
With the possible
exception of Texas Root Rot and Palo Verde Borer, diseases and
insects rarely cause serious damage to desert species. The
overwhelming majority of desert landscape tree problems are
related to detrimental cultural practices (over or under
watering, fertilizing, pruning, shallow or deep planting) or
environmental conditions (soil type, drainage, incompatible
plant mix, heat and sun exposure). Before initiating changes in
cultural practices be certain that the changes will remedy the
problem at hand.