Agriculture Reference
In-Depth Information
Fig 5.37 Cut section showing symptoms of Fusarium wilt inside the
pseudostem.
Fig 5.39 Detail of internal symptoms of Fusarium wilt.
LEAF SPECKLE
■
Cause
The fungus
Mycosphaerella musae
.
Symptoms
Symptoms include a general yellowing of leaves with dark
brown or black speckled patches on the undersides.
Speckling generally does not appear above the fifth- or
sixth-youngest leaf on a plant before f flowering. When the
disease is severe, loss of leaves results in smaller bunches.
Fruit ripen early and unevenly, they are poorly filled and
more susceptible to sunburn.
Source of infection and spread
Infection occurs from spores (ascospores) produced in
small black fruiting bodies (perithecia) on old leaves. These
disperse with the wind to developing leaves where they
germinate. The fungus then grows on the leaf surface for
five to six weeks before penetrating. For this reason,
infection is confined, generally, to the undersides of leaves
that are shaded and remain moist longer.
Fig 5.38 Symptoms of Fusarium wilt inside the pseudostem. Inset:
detail in a transverse section.
