Bulletin 140, Dieback of Citrus Trees


 Since dieback occurs in trees growing under such different
conditions, methods of prevention in one case are not necessarily
 applicable in others. Therefore, methods of
 treatment for different conditions and locations
 will be discussed separately. In all cases the
 trees should be pruned to remove the dead and
 weak wood. Badly injured and stunted trees
 should be replaced with new ones. The trees
 'should be fed at regular intervals and sprayed
 when necessary.
 Overfeeding.-Under this heading are in-
 cluded trees overfed with organic fertilizers,
 and trees located near outhouses, stables, etc.,
 where they are feeding upon organic waste.
 Ammonia should be omitted in whole or in part
 from the fertilizer used about these trees, dur-
 ing a short period. If market conditions will
 permit, a fertilizer formula high in potash
 should be used. Only mineral sources should
 be included in the fertilizer and average to less
 amounts of the fertilizer be applied.
 If trees have been cultivated, this practice
 should be reduced to a minimum. Any plowing
 of the land should be avoided. Where possible,
 the trees should be heavily mulched. Any
 heavy growth of grass, weeds or legumes may
 be cut and used as a mulch about the trees, or
 be removed as hay.
 If the condition is complicated by a lack of
 drainage, or the presence of a hardpan too near
 the soil surface, these conditions can be reme-
 died after the manner suggested under these
 headings.
 Lack of Drainage.-Where the disease is
 brought on by a lack of drainage it is of course
 necessary to get rid of the excess water in the
 soil. This excess may be present only at certain
 periods of the year. This condition must be
 avoided.
 The lack of drainage may be. due to the
 water-table being too near the soil surface on
FIG. 12.-ultiple account of the lowness of the land. Where
 buds account of the lowness of the land. Where