Page 184 - FRUTAS DEL TRÓPICO

184 Frutas del trópico

fruit and inflorescences. Since infected foliage and branches are important sources of inoculum,
fruit set and anthracnose control on fruit are enhanced if disease control is exercised prior to

flowering (Jeffries et al., 1990). Post-harvest control of latent infections is often needed, par-

ticularly if fruit are stored or shipped (Dodd et al., 1997). Hot water treatments should not

exceed 55°C for 5 min, and when hot-water treatment is combined with fungicides (e.g., be-

nomyl or imazalil), water temperatures should be reduced to 52° or 53°C.

Malformation. “Malformation” refers to the abnormal growth of inflorescences that occurs

on affected trees. Primary and secondary axes on inflorescences are shortened, thickened and

highly branched (Ploetz, 2003; Ploetz and Prakash, 1997). Malformed panicles produce up to

three times the normal number of flowers and these are usually larger than normal size. Affec-
ted blossoms often produce vegetative structures (phyllody). Since affected inflorescences do

not set fruit, malformation can greatly reduce fruit production.

Vegetative shoots are also affected, and the names “bunchy top” and “witches’ broom”

are used to describe the distortion of these organs in some areas (Ploetz, 2001). Shoots from

apical or axillary buds are misshapen and have dramatically shortened internodes. Leaves are

dwarfed, and are narrow, brittle and bend back towards the supporting stem. Shoots do not

expand fully, resulting in a tightly bunched appearance of these portions of the plant. If all buds
on a plant are affected, it remains stunted.

The cause of malformation was confused for many years; suggested causes included mi-

tes, nutritional problems, hormonal imbalances, viruses, phytoplasmas, and unknown factors

(Ploetz, 2001). Although a fungal cause for the disease has been confirmed by numerous

researchers in at least six different countries, it is clear that several pathogens are involved. F.

mangiferae (syns. Fusarium moniliforme and F. subglutinans) is most common and widespread,

but at least two other taxa cause these symptoms: F. sterilihyphosum in Brazil and South Africa,

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