Waterhyacinth ( Eichhornia crassipes [Mart.]
Solms), of South American origin, continues to
be one of the most prolific aquatic weeds in the
world. Since its introduction into Mexico in the
late 19th Century (5), it has become a focus of
intense control efforts in that country, as well
in others. From a study carried out to identify
fungi associated with waterhyacinth in Mexico,
two species with biological control potential
were identified: Cercospora piaropi Tharp
and Acremonium zonatum (Saw) W. Games (4).
Two Cercospora spp., C. rodmanii and C. piaropi,
as well as A. zonatum, are known to attack
waterhyacinth. The host specificity of C.
rodmanii (previously considered different tu
C. piaropi in conidia morphology) was demonstrated
in an evaluation of 58 species (1). Rintz
(6) reported that an isolate of A. zonatum from
Louisiana (USA) attacked 10 of 12 species
tested. The aim of our study was to determine
the host specificity of C. piaropi and A. zonatum
(isolated in Mexico) in order to evaluate their
potential as biocontrol agents for waterhyacinth.
The plant species included in the test were selected
on the basis of their economic (8) and
ecological (7) importance and their relation to the
target plant, waterhyacinth (1,8).