Colletotrichum musae (tip rot of banana)

Anthracnose control includes postharvest and preharvest practices in order to reduce its incidence at a commercial stage. Postharvest control involves packing station sanitation, conservation, reduction of wounding during harvest and packaging, and both chemical and physical control methods. Preharvest control refers to reduction of fruit contamination and cultural practices in order to increase the potential quality of fruit (Chillet and de Lapeyre de Bellaire, 1996b).

Reduction of fruit contaminationEliminating the primary (decaying leaves hanging on the banana tree, bunch bracts) and the secondary (floral parts) inoculum sources can be effective in reducing the inoculum of Colletotrichum detected in spore trappings (de Lapeyre de Bellaire and Mourichon, 1997a).The use of plastic sleeves significantly reduces fruit contamination because they prevent rainwater dispersal of inocula forming on the floral parts (Chillet and de Lapeyre de Bellaire, 1996a; de Lapeyre de Bellaire and Mourichon, 1997b). Plastic sleeves should be placed as soon as possible after bunch emergence since maximum inoculum production occurs shortly thereafter. Delays in placing of sleeves (7 to 14 days after the horizontal finger stage) results in significant fruit contamination compared with the normal practice of sleeving at the horizontal finger. Combining early sleeving with elimination of inoculum sources significantly reduces fruit contamination, giving results better or equivalent to those obtained with a postharvest thiabendazole treatment of sleeved fruits without elimination of inoculum sources. These cultural practices could replace postharvest chemical control (Luc de Lapeyre de Bellaire, CIRAD, Guadeloupe, personal communication, 1998).Packing station sanitationCleaning of packing stations is important in order to avoid postharvest fruit contamination. Elimination of leaf material and ripe rejected fruits are particularly important in packing stations because they can provide heavy amounts of inoculum. Floral parts that are removed in packing stations are not important inoculum sources at harvest time (de Lapeyre de Bellaire and Mourichon, 1997a), but should not be removed in dehanding tanks since they introduce other fungi involved in crown-rot disease. The use of clean water is also helpful in order to reduce this disease, as well as the use of disinfectants in water tanks (Arneson, 1960; Slabaugh and Grove, 1982).Reduction of bruisingFruit injuries occuring during harvest and packaging increase disease incidence, and all practices that reduce scarring and bruising are helpful for control. Leaves close to the bunch are commonly removed and different harvest systems have been developed to reduce bruising. Cable-way transportation of bunches is common in Central and South America (Stover, 1972), whereas a cradle-carrier trailer has been developed in the French Caribbean (Marchal, 1993).Physical treatmentsThere are few reports concerning the use of physical treatments to control anthracnose. Kanapathipillai et al. (1988) mention the use of irradiation as a successful means of suppressing C. musae germination and to reduce incidence on green and ripe fruits, but they do not mention possible physiological alterations to irradiated fruit. Burden (1968) mentions that immersion of green fruits in hot water at 55°C for 2 minutes reduces disease incidence, but in Guadeloupe, heat treatment effectively controlled anthracnose only when associated with a fungicide (Luc de Lapeyre de Bellaire, CIRAD, Guadeloupe, personal communication, 1998).

Bananas are commonly treated with an antimitotic product (benomyl, or more commonly thiabendazole) in the packing station before boxing, and this control has proved effective in most countries (Frossard, 1969; Stover, 1972; Rippon et al., 1973; Shillingford, 1978; Slabaugh and Grove, 1982; Ram and Vir, 1983). Fungicides are applied in different ways, such as dipping or spraying under automated chambers, with good wetting of the fruits being the most important factor to ensure treatment efficiency (de Lapeyre de Bellaire and Nolin, 1994). Resistance to antimitotic fungicides has emerged in different countries (Griffee, 1973; Quimio, 1976; Hostachy et al., 1990; Johanson and Blasquez, 1992), mainly in relation to preharvest aerial sprayings for control of sigatoka disease (Mycosphaerella musicola) or black leaf streak disease (M. fijiensis) (de Lapeyre de Bellaire and Dubois, 1997). Sterol biosynthesis inhibitors exhibit good postharvest control of anthracnose and crown rot diseases (Espinoza et al., 1991; de Lapeyre de Bellaire and Nolin, 1994).Fungicides are commonly applied as postharvest treatments, nevertheless preharvest applications at 7 to 15 day intervals from flowering to harvest proved efficient in controlling anthracnose (Rawal and Ullasa, 1989) or banana tip rot (Temkin-Gorodeiski et al., 1975).Postharvest control with thiabendazole is less important in certain areas of Guadeloupe on fruits inoculated 15 days after bunch emergence and wounded at harvest, as compared with fruits coming from other areas (Chillet and de Lapeyre de Bellaire, 1996b). Effects of this variation in fruit quality have been confirmed in surveys conducted in Martinique and Guadeloupe where fungicide efficacy ranged from 40 to 98% (Chillet et al., 1998). Fruit texture (firmness and pulp hardness) is linked to the altitude of the plantation and mineral composition, although more work is needed to clarify how fruit quality and cultural practices affect ripening and disease susceptibility.