120 Papaya
10.9 Anthracnose
Anthracnose is the most serious disease affecting the ripened fruit caused by
Colletotrichum gloeosporioides Penz., in which light yellow patch appears on the
south west side exposed to sun in India. It is an important papaya disease in Hawaii,
Mexico and India (Rawal 2010). This fungus attacks not only the fruit on which it
causes the most damage, but also the petioles of the low, older leaves that begin to turn
yellow. The disease prominently appears on green immature fruits (Figure 10.8a).
10.9.1 Symptoms
The disease symptoms are in the form of brown to black depressed spots on the
fruits. The initial symptoms are water-soaked, sunken spots on the fruit. The patches
slowly soften, turn brown and extend to half fruit. The centers of these spots later
turn black and then pink when fungus produces spores (Figure 10.8b). The flesh
beneath the spots becomes soft and watery, which spreads to the entire fruit (Hasan
et al. 2012). Small, irregular-shaped, water-soaked spots on leaves may also be seen.
These spots eventually turn brown. On the fruits, symptoms appear only upon rip-
ening and may not be apparent at the time of harvest. Brown sunken spots develop
on the fruit surface, which later on enlarge to form water-soaked lesions. The flesh
beneath the affected portion becomes soft and begins to rot (NHB 2002). A disease
resembling anthracnose but which attacks papayas when just beginning to ripen,
was reported from the Philippines in 1974 and the causal agent was identified as
Fusarium solani. A strain of this fungus produces ‘chocolate spot’ (small, angu-
lar and superficial lesions) on fruits. The fungus causing anthracnose on fruit also
attacks the petioles of lower leaves as they begin to die and shed from the plant.
FIGURE 10.8 (See colour insert.) Fruits damaged by anthracnose disease: (a) unripe and
(b) ripe stage.