Bulletin 229, Diseases of Citrus in Florida


withdraw water from the fruits even before the moisture in the
soil has become very materially depleted. On going into a grove
in the afternoon of a warm day when the humidity is low, fruits
may be found to be soft to the touch even though the moisture
content of the soil may be well above the wilting coefficient of
the leaves. Upon examination of the same fruits the following
morning they will be found to be turgid. This condition may
become especially noticeable when the weather is dry and a
strong wind blows for a number of days. The withdrawal of
water from the fruits by the leaves is an important factor on
many soil types in Florida when the water supply in the soil be-
comes low. Abundant experimental work has been done to dem-
onstrate that water may be withdrawn from the fruit to an in-
jurious extent by the leaves long before the leaves themselves
exhibit any sign of wilting.
 CONTROL OF INTERNAL DRYING
 It is believed that the internal drying of citrus fruit can be
reduced to a minimum where plantings are made on sour orange
or other rootstock that does not promote drying out of the fruit
and on soils of good moisture-holding capacity. The moisture-
holding capacity of light sandy soils, on which the use of rough
lemon stock is required, can be improved by building up the sup-
ply of organic matter and by irrigation, or both. The texture
and quality of citrus fruit in general, especially when on rough
lemon stock, can be improved greatly by reducing cultivation
or eliminating it entirely.
 CREASING
 A trouble known as creasing or crinkle, which results in fruits
with weakly developed rinds, is of more or less common occur-
rence wherever citrus fruits are grown. This trouble appears
to develop most frequently on oranges but it is only occasionally
that consequential loss results. Fruits affected by creasing are
characterized by irregular grooves extending in various direc-
tions over the surface, caused by the rind sinking. The creas-
ing may vary from a mere trace to instances where it occurs
both longitudinally and crosswise to form irregular patterns.
If the affected fruits are examined closely, it will be found that
the inner white part of the rind is usually very thin or poorly
developed and often cracked or pulled apart under these grooves,
thus resulting in the sinking of the outer part of the rind which