PRESS BULLETIN 133 December 1.1, 1909
Florlda Agrcullural Experiment Sltaton
WINTER PRUNING FOR WITHERTIP
BY H. S. FAWCETT
Withertip is one of the worst fungus diseases of citrus trees in Florida.
In the winter season, diseased trees may be distinguished by the yellowing
and falling of their leaves, the dropping of their fruit, and the dying of their
twigs and branches. A citrus tree affected with withertip will begin to lose
its inside leaves. The outer leaves then turn yellow and fall, leaving many
bare and discolored branches. The fruit also drops, with or without spotting.
HOW TO PRUNE
The important thing in pruning is to cut out enough of the wood, in order
to get rid, not only of the bare branches, but also of all the branches that
show even a slight sign of the disease. In severe cases of withertip, there
are seen, in addition to bare branches, many limbs on which the yellowish
leaves are about to fall. Close examination will show that the disease is
slowly making its way back and poisoning 'these limbs. This poisoning may
start from an infection at the tip, orfrom an infection on a side branch lower
down, from which the poisonous effect has spread to the main limb. Some-
times only one side of a tree, or only one branch, is severely affected; while
the remaining part of the tree is uninjured. Whatever may be the conditions,
it is important to get rid of these poisoned limbs. All limbs that show the
beginnings of the disease must be taken out. 'Drastic measures must be em-
ployed, and many bearing limbs may have to be sacrificed. To prune only
half-heartedly may make matters worse, rather than better, When pruning,
care should be taken to make smooth cuts, usually at the base of a branch or
limb, so as not to leave any projecting stubs, in which infection is almost sure
to start again. After pruning, paint the larger cut surfaces with carbolineum
or pine tar.
The grove should be given unusual care after a severe pruning of this
kind. It should be fertilized, so as to bring about a vigorous healthy growth,
and to render the trees resistant to further attacks of the fungus.
WHEN TO PRUNE
Winter pruning for withertip should be done between the middle of De-
cember and the middle of January. It is important not to delay the work be-
yond this date. Do not prune while the new growth is putting out, for this is
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almost sure to result in injury rather than benefit. Begin the work at once,
and do not consider the looks of the trees, but take out everything that shows
the presence of the disease.
The beneficial results already obtained on hundreds of acres of groves
treated'4n this way, under the direction of Experiment Station workers, have
proved the effectiveness of this treatment.
OTHER EFFECTS OF WITHERTIP
Different results of the attack of the withertip fungus are seen at other
seasons of the year. These vary according to weather conditions and the
part of the tree affected, and need different treatment. Some of these
effects of the disease are: (1) dropping of bloom; (2) browning of tender
leaves; (3) brown spotting of older leaves; (4) spotting of fruit; and (5)
tear-staining of fruit.
State papers please copy.