at Parrot Jungle and Gardens
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plant families can boast year round color like the Canna Lily. These relatives
of the Heliconias, Bananas, and Birds of Paradise are easily grown in
sun locations the red, yellow, or orange flowers lend a colorful accent
to any garden or patio. Even the foliage comes in different colors. Although
usually green, some plants will have red or variegated leaves. Unfortunately,
lush beds of Canna lilies are an uncommon sight in our region.
is very labor intensive; maintaining healthy plants requires almost daily
care. Our high humidity encourages fungi and high year-round temperatures
offer insects perfect breeding conditions. Below are some of the difficulties
of growing Cannas along with some of the solutions to those problems.
The fungal problems affect both the foliage and the flowers. An orange
looking rust often appears on the leaves and stems of the plants. These
are the fruiting bodies of a fungi commonly called Frangipani rust. When
this rust first appears, the foliage that it is on must be removed and
discarded (if you leave it there you will be allowing the fungi to propagate).
The best method for fungal control is prevention and sanitation. However,
flowable copper (which is copper in a liquid form) can be sprayed on the
stems and foliage (top and bottom of the leaf) to help prevent fungal
problems before they occur. Although used commercially, copper is not
practical for home use because of its toxicity.
are sometimes affected by a gray, fuzzy mold called Botrytis. Under humid
conditions it is often found growing on the older flowers. Remove the
old flowers so the mold does not spread to the new flowers.
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and most obvious insect problem is a caterpillar called a "leaf roller".
This is the culprit that devours the leaves. During the day they reside
on the underside of the leaf inside a little hammock that they make when
they cut out a portion of the leaf and curl it over themselves and glue
it to the leaf above. They are active at night and, if allowed to grow
unchecked, will eventually strip the plant of all its foliage. Control
of these caterpillars can be achieved by using a spray that contains the
ingredient Bacillus thuringiensis. This compound is supposed to be nontoxic
to mammals and birds. It is quite effective when applied with a spreader
sticker to the undersides of the leaves. (Any chemical applied to the
underside of a leaf will probably last longer because there is less exposure
to water and sunlight) The use of a commercial spreader sticker (an agent
that helps break down the leaf's waxy cuticle) is important because the
leaves of the Canna lily are very waxy; that makes it difficult for anything
to stick. A household detergent will also do (usually two tablespoons
to a gallon of spray).
These tiny insects can be seen without a magnifying glass. They are dark,
slender and about the length and size of the lead showing on a sharpened
pencil. They suck the juices of the flowers causing them to wilt. Thrips
are sometimes found on orchid flowers. An effective control that is harmless
to the plants can be achieved by removing all the flowers from all the
Canna Lilies on site at the same time. This usually has to be done only
|Yellow Canna Lily
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microscopic members of the spider family make their living by sucking
the sap out of plants. Damage from spider mites first appears as yellowing
of the leaves. If this damage is left unchecked, the plants will eventually
die. Spider mites are first found on the undersides of the leaves, although
they can end up covering up the entire plant. About the size of the head
of a pin, they are easy to see with a magnifying glass. They may be white
but some of the common species have red dots, hence the 2-Spotted Spider
Mite. Common insecticides are useless; commercial miticides are more effective,
but the best home control is removal of the food source. As a leaf begins
to die (senesce), the nitrogen within it becomes more nutritious for the
mite. Since the lower leaves are the oldest, cutting the lower leaves
of the plant eliminates this valuable food source.
The introduced Cuban Brown Snail also causes damage to the foliage and
flowers. A commercial snail bait is effective. However, removal of all
debris under and around the plants will eliminate daytime hiding places
for these nocturnal mollusks, usually eliminating the need for snail bait.
Full sun and soil high in organic material will produce vigorous plants.
A good rule of thumb is to allow Cannas to bloom only twice; removal of
the entire plant stem at this point will remove fledging populations of
insects. Do not wet the foliage. Water the plants at ground level - this
will help prevent fungal problems. Fertilize often. Cannas grow rapidly
and respond well to a balanced fertilized (20-20-20 et.) and, remember,
keep the plant bed clean.