in approximately 8 months. It was noted that the individual plants vary
in size from a few inches under poor growing conditions, to several feet
under optimum conditions in well aerated canals. Propagation is accom-
plished primarily from vegetative reproduction rather than from seed. It
is doubtful if the seeds will germinate under water in south Florida. The
hyacinth does not tolerate brackish water. It is killed by prolonged
freezing, and will not survive where water temperatures remain much above
900 F. for long periods. Cattle often eat the plants; however, the water
content averages about 95 percent and they afford little sustenance.

 THE CONTROL

 Water hyacinths are susceptible to the effects of 2,4-D (2,4-Dichloro-
phenoxyacetic Acid) and can generally be controlled by an application of
1 pound of 2,4-D acid equivalent per acre.

 When treated with 2,4-D the plants exhibit the following symptoms:
a few hours after spraying there is a marked bending of the leaf stems;
in about a week plants wilt and become brown in color; in three to four
weeks they die and form a floating mass which decomposes and sinks to
the bottom of the ditch about the sixth to eighth week after treatment.
Water current, wave action, and wind movement appear to be factors in
causing the dead material to sink. Studies in Louisiana indicate that the
plants sink quicker under heavier rates of 2,4-D application. This has
not been confirmed under south Florida conditions.

 Water hyacinths are killed more rapidly in warm weather than in cool.
A poor kill may be obtained if the weather is cool or if rain falls within
6 hours after treatment with 2,4-D.

 The quantity of 2,4-D acid used for the control of water hyacinths,
as well as for general weed control purposes, is not harmful to fish or
to warm-blooded animals.

 TYPES OF 2,4-D

 The most common types of 2,4-D which are available commercially are:
 (1) Sodium salt of 2,4-D
 (2) Amine salts of 2,4-D such as dimethylamine, alkanolamine, etc.
 (3) Esters of 2,4-D
 (a) high volatile types such as butyl, ethyl, isopropyl and
 methyl esters
 (b) low volatile types such as the propylene glycol butyl
 ether, and other low volatile esters of 2,4-D

 The sodium salt is available as a powder and the amine salts and
esters as liquids. Most of the commercial types of 2,4-D can be mixed
with water to obtain a spray mixture.

 For general weed control, including water hyacinths, the amine salts
are recommended. In south Florida the amine liquid containing about 4
pounds of 2,4-D acid equivalent per gallon is generally used in preparing
the spray mix.