Page 179 - FRUTAS DEL TRÓPICO

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diseases of impoRtant cRops in chiapas

have thickened, darkened basal scars, but those of the latter, P. musae, do not; the teleomorphs
are indistinguishable.

Conidia and ascospores of the fungus are both infective. They are formed under high

moisture conditions and are disseminated by wind (Rutter et al., 1998). Management strategies

vary according to the cultivars that are grown, the environment, and the intended market for

the fruit (Fullerton and Stover, 1990). In export plantations of dessert bananas and plantains,

frequent applications of fungicides are usually needed. Application frequencies can range as

high as 36 yr-1 for dessert bananas and 19 yr-1 for plantains (Jones, 2000). Chemical control

has evolved considerably over the last 60 years (Table 6) (Ploetz, 2000).

Cultural practices are also useful. These include the removal of leaves with mature spots,
and reducing humidity within plantations with increased spacing between plants and efficient

drainage with permanent canals and pumps. Smallholders, who cannot afford these control

measures, are affected most by black Sigatoka. For example, plantain yield losses of 33% and

76% were recorded during, respectively, the first and second cropping cycle in west Africa

(Mobambo et al., 1996). Under marginal conditions production is often abandoned due to low

yields (Jones, 2000).

Some cultivars resist black sigatoka, but resistance is poor among many important types
of banana, including export dessert AAA, AAB plantain, highland AAA and AAB dessert (Table

7). Furthermore, clones that resist black sigatoka may be susceptible to other problems such

as Panama disease, nematodes and weevil borer (Cosmopolites sordidus).

Panama disease (Fusarium Wilt). Panama disease, which is also known as Fusarium wilt,

is caused by the soilborne fungus, F. oxysporum f. sp. cubense. It originated in southeast Asia,

but was first reported in Australia in 1876 (Ploetz and Pegg, 1997). It was responsible for des-

tructive epidemics in export plantations of ‘Gros Michel’ before it caused the trades to convert

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