Bulletin 229, Diseases of Citrus in Florida


 In order to be effective, remedial measures must be applied
before the disease has progressed to such an extent as to kill a
large percentage of the roots and girdle the root crown since,
after the disease has progressed to this extent, the death of the
tree is inevitable. Unfortunately, this extent of development
of the trouble usually is required before the symptoms of decline
develop in the top of the attacked tree to warn the casual ob-


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 Fig. 23.-Grapefruit tree treated for Clitocybe mushroom root rot,
 showing the dead roots and diseased areas of bark cut out.
server that something is wrong with the tree. However, attack-
ed trees often can be located quite a while before the tops of the
trees have declined to any considerable extent by finding the
clusters of the mushroom-like fruiting bodies of the root-rot
fungus or sometimes only a slight gumming area of bark at the
bases of the trees.
 Unless the top of the tree has declined considerably, the extent
to which the disease has attacked the root system can be de-
termined only by removing the soil sufficiently from around and
under the root crown and crown roots. This requires removing
.a basin of soil with a radius of from two to three feet from the
base of the tree, working carefully so as not to injure the roots.
Unless facilities are available for washing, the soil should first