Agriculture Reference
In-Depth Information
onthefarmsinwhichitappeared.Thisraisedthepossibilitythatsomeen-
vironmentalfactortriggeredamutationinMycosphaerellamusicolaLeach
giving rise to the newly dominant Black Sigatoka strain that proved to
be much morevirulent than Sigatoka. Researchers subsequentlyclassified
Black Sigatoka as Mycosphaerella musicola fijiensis, a fungus that United
FruitpathologistRobertStoverdetectedonpreservedplanttissuesamples
collected in Fiji in the 1920s, indicating that the pathogen did not have
its genesis in the Sula valley. Nevertheless, the consistent pattern of Black
Sigatoka replacing Sigatoka leaves open the possibility that changing pro-
duction practices—including the use of Dithane—altered agroecological
conditions in such a way as to favor the proliferation of Black Sigatoka.
36
The company brought the initial outbreak of Black Sigatoka under
controlthroughmultipleapplicationsof Benlate,asystemicfungicidethat
company scientists first field-tested in 1967.
37
A second outbreak of Black
Sigatoka occurred in 1974 following Hurricane Fifi. When aerial spraying
resumed after the storm, about 4,800 hectares of infected farms received
Benlate treatments every other week. Benlate proved to be an effective
short-term control for Black Sigatoka but the rapidity with which popu-
lations of fungi developed resistance to the fungicide limited its poten-
tial as a long-term solution. In order to slow the buildup of Benlate-
resistant strains of the pathogen, United Brands' scientists ordered that
applications of Dithane be made every third cycle.The companyachieved
a tenuous control over the pathogen through high frequency applications
(35-45 times/year) of systemic fungicides. Not surprisingly, the cost of
Black Sigatoka control rose sharply following 1974 and within a decade
accountedforabout26percentofallpre-harvestproductioncostsinHon-
duras.
38
Standard Fruit began alternating cycles of Dithane and Benlate
in 1975. Within five years, the buildup of resistant pathogen populations
prompted the company to switch to another systemic fungicide called
Bravo. In 1982, following a heavy outbreak of Black Sigatoka in the Stan-
dard Fruit's Aguán valley farms, the company began to rotate Bravo with
applications of a Dithane-oil-Benlate-water ''cocktail.''
39
For the remainderof the twentieth century, the export banana indus-
try would be ''running to stand still'' on a treadmill driven by expensive
agrochemical inputs and ever-evolving populations of fungi. The history
of Sigatoka and Black Sigatoka control on export banana farms calls into
question the widely held notion that post-World War II innovations in
chemical pesticides reduced economic losses from pests and pathogens in
commercial agriculture.
40
The switch to low volume applications of fun-
gicides helped the fruit companies to reduce laborcosts in the early 1960s,
