Prevention Is Better Than Cure


 By
 Errol Chichester
Extension Agent Pest Management


 Healthy plants are more able
 to withstand diseases

 Throughout our lives, we have heard the saying "an
ounce of prevention is better than a pound of cure." This
saying does not only pertain to situations affecting human
beings but also to conditions affecting plant health.

 Plant diseases contribute to substantial losses in vege-
tables, fruits, nuts and ornamentals. Preventing disease in
plants will go a long way in helping to provide food to feed
our steadily increasing population and ornamentals to
beautify our islands.

 In order for a disease to develop, three ingredients must
be present: 1) a susceptible host plant 2) a disease-
producing agent and 3) an environment favorable to
disease development. Thus, if you eliminate or reduce the
intensity of one or more of these ingredients, the resultwill
be a corresponding decrease in the occurrence or severity
of the disease. There are several preventive measures that
can be taken by farmers and home gardeners. By following
these measures, you can reduce or eliminate plant disease.
Consequently, you will have reduced yield loss as well as
the use of expensive chemicals.

 These preventive measures involve five approaches. They
include: reducing plant stress; keeping diseases out of our
islands, nurseries and farms; eradicating it when it occurs;
using resistant varieties; and protecting plants.

 Plants are stressed by a number of factors. Among them
are improper watering, lack of nutrients, unsuitable plant-
ing medium and poor drainage.

 Lack of water produces stress in plants. This is shown by
symptoms such as wilting, tip or marginal burn of leaves,
twig and branch dieback, yellowing and early defoliation of
older leaves. To prevent drought stress you should water


Always maintain healthy plants


the root zone of plants thoroughly as needed, use plants
that are adapted to your conditions and apply a mulch
around plants to reduce evaporation.

 On the other hand, as the saying goes "Too much of one
thing is good for nothing." And it's true too much water
can also be detrimental to plants. Excess water fills the air
space in the soil and decreases the amount of oxygen avail-
able to plants. In saturated soil, no oxygen is available for
plant use. This condition, if prolonged, will eventually kill
the plant. Overwatering is most common with claysoils and
in pots with inadequate drainage. To prevent poor drain-
age, use sandy soil, add vermiculite to soil mix or put rocks
in the bottom of your pots.

 If your plants lack a well balanced nutrition, they will not
grow properly. Many soils lack certain nutrients and this
may cause the problem. In which case, you should add
chemical fertilizer, animal manure or compost to the soil.

 Improper pH also accounts for nutrient unavailability.
The measure of the acidity or alkalinity of solutions is its pH.
A soil pH determines its ability to make the nutrients avail-
able to the plants. Some plants can even "starve" to death if
planted in soils that are unsuited for them. Lime or sulfur
may be used to correct the pH. Lime increases the pH, while
sulfur decreases it.

 Yet another factor that contributes to plant stress is a
 build up of salts in the soil. This may be caused by over-
fertilization. The use of potable or well water can also cause
this problem as it often contains high concentrations of
salts. Salt build-up is indicated by a white crust on dry soil
surfaces or on containers in which plants are grown.

 Plants range in their tolerance to salts. If you have a prob-
 lem with salty soils you might consider planting salt-tolerant
 varieties, or reducing the use of potable and well water. If
 plants grown in containers have saucers or catch pans,
 remove them so that excess water can drain out of the con-
 tainer to prevent salt accumulation.

 Quarantine is one way of keeping disease out of our
islands. This is accomplished by not allowing certain plants,
fruits or vegetables, that often carry a particular disease into
the territory from other Caribbean islands. Many of us,
while traveling, will have had to fill out forms which ask if
we are carrying plants, fruits, or vegetables. Or, some of us
may have certain agricultural products taken away by
Customs officials. They were not trying to spite us (some of
us think that they want the fruits for themselves) but were
trying to intercept plant materials that frequently carry
diseases. To avoid any problems when traveling, you may
want to contact the Plant Protection and Quarantine (PPQ)
office. On request, they will provide information on the
regulations concerning any particular plant, fruit or vege-
table that you are interested in. The phone numbers are
774-2787 and 778-1696.

 Another means of keeping diseases out of your gardens
and farms involves a simple effort by the farmer, gardener,
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