Florida Agricultural Experiment Station


 A number of conditions have been found to favor the develop-
ment of damping-off. Among these are poor drainage, improper
watering, excessive shading, a high degree of humidity, over-
crowding, and planting on infected soils. Control measures con-
sist largely in the careful management of the seedbed to avoid
these conditions. Only well-drained soil should be selected for
a citrus seedbed. Since infection is most common at the ground
level, this part should be kept as dry as is practicable. If the lo-
cation selected has been used previously for a seedbed and damp-
ing-off occurred at that time, the soil should be disinfected be-
fore the new seedbed is established. This may be done by treat-
ing with steam under pressure, as is done in the case of soil
sterilization in greenhouses, or by the use of 1 part of com-
mercial formaldehyde to 50 parts of water, applied at the rate
of 1/ gallon to each square foot of soil surface. After the soil
is sprinkled with this solution it should be covered for a few
days with canvas or fumigation tent cloth to permit the fumes to
kill the soil fungi. If the disease shows up in planted beds
spray the plants and soil with 3-3-50 bordeaux mixture. If
prompt attention is given to treatment the disease usually can
be checked.
 SOOTY MOLD
 Caused by Capnodium citri Berk. & Desm.
 Sooty mold is abundant throughout the citrus-growing sec-
tions of the world wherever whiteflies, aphids, scales, and other
honeydew-excreting insects feed on the trees. It is a black
fungous growth which forms a filmy membrane over the surfaces
of the leaves, twigs, and fruit of citrus and many other trees.
 The sooty mold fungus does not attack citrus tissue but is
simply a saprophytic organism developing on the surface of the
plant parts in the honeydew excreted by the larvae of such in-
sects as whiteflies, aphids, and scale-insects. These insects are
gregarious in their habits and, consequently, the sweetish liquid,
termed honeydew, that is excreted by them collects in consider-
able quantities on the various parts of the tree. This sweetish
excretion also proves very attractive to ants. If the insects are
few or the amount of honeydew is slight this black mold may
occur in limited spots but, when the accumulation becomes
abundant, the entire surface of the leaves, fruits, and twigs may
be covered by a dense, continuous black membrane composed of