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RESUMENEl control de la Sigatoka negra (Mycosphaerella fijiensis) se basa en el uso continuo de fungicidas y prácticas de cultivo. El control cultural reduce las fuentes de inóculo del patógeno y las condiciones favorables para su desarrollo, así como incrementa el vigor de las plantas. Para combatir la enfermedad se requiere conocer su comportamiento a través del tiempo, su relación con el clima y las prácticas de manejo. La práctica más importante para reducir la fuente de inóculo es la remoción de hojas afectadas o porciones de éstas. El tejido removido se deposita en el suelo y es factible la aplicación de urea para acelerar su descomposición. Una práctica alternativa es el "minicomposteo", que consiste en colocar la hojarasca y plantas cosechadas en pequeños montones para su rápida degradación, lo cual reduce el inóculo e incorpora nutrientes y materia orgánica al suelo. La poda temprana de las puntas de hojas jóvenes (antes de presentar lesiones esporuladas) y la eliminación rápida de plantas cosechadas disminuyen el inóculo. También, el manejo agronómico del cultivo como densidad de plantación, sistemas de drenaje, métodos de riego, control de malezas, fertilización química-biológica y control de nematodos, ayuda a reducir las condiciones favorables para el desarrollo de Sigatoka negra e incrementar el vigor de las plantas. Palabras clave: control cultural, Mycosphaerella fijiensis. ABSTRACT Cultural practices for the management of black sigatoka in bananas and plantainsBlack sigatoka (Mycosphaerella fijiensis) control consists in the continuous use of fungicide sprays and cultural practices. Cultural control reduces inoculum sources of the pathogen and favorable environmental conditions for its development, as well as it increases the vigor of the plants. In order to manage the disease it is necessary to know its behavior through the time, its relationship with the weather and the crop management. The most important cultural practice to reduce the inoculum source is the removal of the whole affected leaves or only the diseased portions of the leaves. The removed tissue is placed over the ground and the use of urea is feasible to accelerate its decomposition. An alternative practice is the "mini-composting" that consists in forming small heaps with the dead leaves and harvested plants for its quick degradation, which allows to reduce the pathogen inoculum and to incorporate nutrients and organic matters into the soil. The early pruning of the tips of the young leaves before they show symptoms of the disease and the quick elimination of harvested plants reduce the inoculum. Also, the agronomic management of the crop helps to reduce the favorable conditions and to increase the vigor of the plants: this management considers plantation density, drainage systems, irrigation methods, control of weeds, chemical-biological fertilization, and nematode control.

This work was conducted for evaluate the influence of clear and black polyethylene mulches, used alone or combined with floating rowcover (FRC) and plastic perforated microtunnels, on insect populations, growth and yield of muskmelon. Treatments evaluated were 1) clear plastic + FRC, 2) polyethylene perforated microtunnel, 3) clear plastic + polyethylene not perforated microtunnel, 4) black plastic + FRC, 5) clear plastic, 6) black polyethylene, 7) clear plastic + oil, and 8) bare soil. Aphids and sweetpotato whitefly adults and nymphs were completely excluded by floating rowcovers while the plots covered. The export and national quality fruit yield was major in the mulched beds in relation to control. Clear polyethylene mulch + FRC increased number of fruit and export marketable fruit of cantaloupe (45.2% and 44.8%) with respect to black plastic + FRC, respectively. It is proposed that, under tropical conditions and under high insect stress, mulches combined with floating rowcovers should be selected for their effects on insects in addition to their effects on melon yield. Polyethylene microtunnels were found not economical for cantaloupe production in western Mexico.

Research was conducted to evaluate the use of plastic mulches in the production of cucumber under micro-irrigation in tropical conditions. Clear (C) plastic muich installed on beds increased the fruit number and the yield of cucumber (Cucumis sativus L cv. Fanci Pack) in comparison to unmulched (U) soil, during 1992-1993. White (W) and black (B) plastic mulches showed a moderated effect. Marketable yields of 63.3, 46.2, 44.8 and 21.6 t/ha were achieved under C, W, B and U treatments respectively (P<0.05). The plastic mulches reduced the number of days to flowering and to first harvest and increased the fruit number. It is concluded that clear plastic mulch is more adequate for tropical conditions than black or white plastic mulches.