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- Will my citrus tree bear more fruit if I trim it back?
Pruning healthy, mature citrus trees usually reduces yield in proportion to the
amount of foliage removed and can delay fruiting of young, nonbearing trees.
Pruning should therefore be limited to that required for future canopy bearing
surface development and for the conduct of efficient cultural and harvesting
operations.
- What causes curled and crinkled leaves on citrus
trees?
It may be Citrus Leaf Miner Damage or Aphid Damage. Citrus Leaf Minor damage
This insect is the maggot of a tiny fly that lays eggs into the leaves. Maggots
hatch from the eggs and "mine" their way through the leaves causing them to cup
and crinkle. "Squiggly" lines can also be seen in the affected leaves. This
insect is not harmful to the health or fruit production of established trees.
Young citrus trees may benefit from sprays of horticulture oil which
interfere with the fly's ability to lay eggs into the leaf. Spray each time a
new flush of growth appears. Read the label of oil product carefully, as
horticulture oil can burn the leaves when applied incorrectly.
Curled, distorted leaves can also be the result of aphid insects. These pests
have needle-like mouthparts which pierce the leaves and feed on the plant sap.
They always feed on the newest, most tender growth. As these leaves mature, they
exhibit the damage, but by then the aphids are long-gone. Aphid damage is mostly
aesthetic and can be ignored. If aphids are detected, they can be easily
controlled by forceful sprays of water or by insecticidal soaps.
- My citrus tree leaves are covered with black
"stuff"?
Sooty Mold appears as a black, sooty growth on the upper side of leaves. It is
relatively harmless, but indicates that an insect was or is present (usually
aphids, whiteflies or scales). As these piercing-sucking insects feed on the
undersides of the leaves, they secrete a sticky, clear fluid that drops onto the
leaves below. Sooty mold grows upon this secretion.
- There is a white and orange scale-like thing
growing on the undersides of my citrus leaves?
It sounds like Aschersonia (Friendly Fungus). This beneficial fungus grows on
and kills whitefly insects. It looks scary, but it's a good thing.
- The fruits on my citrus tree are splitting and
falling off?
The problem of splitting fruits usually occurs in the early fall. The citrus
fruits are mature in size and the peel is not expanding. If heavy rains occur,
citrus trees absorb water and force it into the fruits. The peel cannot expand,
and instead splits. The fruit will begin to decay and attract insects. Splitting
fruit is also associated with young trees and certain varieties.
- How Do I Fertilize Citrus?
Citrus which has been planted in the ground over five years should be fertilized
3x per year: (January/February, May/June, and October/November) at the rate of
one pound per year of the tree's age (counting from the time it is planted) up
to a maximum of 10 pounds per application.
Young trees should receive between 4 - 6 applications per year at a rate of
one pound per year of age. An 8-8-8 fertilizer containing secondary nutrients
(particularly magnesium, manganese, copper and boron) is recommended. Apply the
fertilizer to the entire rooting area which extends from the trunk out to
several feet beyond the drip line of the tree.
- The peel on some of my oranges has turned brown?
Tiny rust mites feed on the peel during the summer causing a russeting of the
peel. The interior quality of the fruit is not affected. Homeowners can ignore
this, but if desired, rust mites can be controlled or prevented by spraying the
tree with a material called Kelthane. One application is usually enough to
control the pest. Apply Kelthane when the fruit is almost mature. Read the
directions on the label before applying. The fruit is still edible but will not
change back to its original color.
- There are yellowish spots on the leaves of my
citrus and many leaves are dropping off?
The first appearance of the Greasy Spot Fungus disease is as a yellow green
spot, which becomes orange yellow. In the latter stages, the area becomes raised
on both sides of the leaf, and the color becomes tan, then dark brown to black.
The tree must be sprayed with copper fungicide before symptoms occur. Once
symptoms appear, no amount of spraying will cure the problem.
- The peel of my citrus fruit looks like it has
scars?
Fruits blow about in heavy wind and rub against twigs, other fruits, leaves,
etc. It does not affect interior quality of fruit.
- Something is chewing holes in the leaves of my
citrus tree. Will it hurt my tree?
Usually either a grasshopper or caterpillar. Damage is usually contained to a
small proportion of leaves and should be ignored. The caterpillar is called an
Orange Dog, and is the larval stage of the beautiful Giant Swallowtail
butterfly.
- Why do my citrus blooms drop without setting?
Citrus must be planted 3 to 4 years before it becomes mature enough to set
fruit. It may bloom prolifically, but it will drop its blooms. Even mature
citrus sets only a very small amount of its bloom (less than 1%).
- Most of the leaves on my young citrus tree are
yellowing and dropping?
Foot Rot disease may be the problem. This fungal disease attacks the tree at or
just below ground level, rotting through the bark and conducting tissue thereby
stopping the flow of water and nutrients in the tree. It is aggravated by
planting citrus too deep. The top of the root ball should be flush with the soil
surface. You should also avoid mulching citrus, poorly drained soils or over
watering (citrus will thrive on an inch of water (or less) a week. Yellowing
veins is a typical symptom of foot root or root rot disease.
- My citrus tree has a white covering on the trunk
and branches that appears to be spreading throughout the tree?
From your description it sounds as though you have "snow scale." It can be
controlled by using an oil spray mixed with malathion.
There is a natural predator of this scale, but it is not always present and
the tree will need to be sprayed twice. The interval between applications should
be fifteen to twenty days.
- My citrus tree has grass and weeds growing close
to the trunk of the tree. Should these be removed?
Grass and weeds should never be permitted to grow near the trunk of citrus
trees. This may hold moisture around the trunk and encourage the attack of a
fungus called "foot rot." This fungus, if it become virulent, will ultimately
kill the tree.
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