Recinto Universitario de Mayagüez
Facultad de Ciencias Agrícolas
Departamento de Horticultura
Eficacia de Extracto de Algas Marinas (Ascophyllum nodosum) para el
Control de Ceratoma trifurcata en el Cultivo del Frijol
Eduardo Pérez Cruz
Prof. Pablo Morales Payan
EFFECT OF ALGAE EXTRACT (ASCOPHYLLUM NODOSUM) ON CHRYSOMELIDS AFFECTING AN
Abstract. An experiment was conducted to determine the effect of Ascophyllum nodosum extract on Ceratoma trifurcata (Forster) on an organic cowpea field. Cowpea was sown directly into the terrain and applications of algae extract were foliarly applied at three intervals once plants had reached an advanced vegetative state at different product concentration rates: (1) nothing,(2) 2.5mL, (3) 5.0mL, (4) 10.0mL, (5) 20.0mL and diluted in 1 liter of water which was evenly distributed for each treatment. The variables analyzed for this experiment were leaf defoliation and production yield in dry bean weight. Leaf damage values were assessed three times during the study by number of defoliation spots based on representative leaves per plot. No significant difference wasfound between treatments for any of the variables analyzed and general percent values for defoliation damage caused by Ceratoma on cowpea by the end of harvest were below the threshold values for pest control on commercial production of the crop.
Cowpea is susceptible to the attack of Ceratoma trifurcata. These insects are occasionally important leaf defoliators, showing substantial seasonalfluctuations with the capacity to destroy the cotyledons and completely defoliate the first true leaves, subsequently killing young seedlings when found at high populations affecting the crop and are important vectors of viral disease on bean crops such as Bean Pod Mottle, Yellow Mosaic, and Southern Bean Mosaic (Van Wychen, 2004). The bean leaf beetle, Ceratoma trifurcata Forster, is considered themost efficient vector of Bean Pod Mottle Virus (Ghabrial, 1983) which not only reduces yield, but also reduces seed quality, as seeds from infected plants may be discolored (Giesler, 2002). Lesions caused to the plant may open infection sites for other seed-staining fungi (Delate, 2001).
Bean leaf beetles represent approximately an additional 20% in the total costs of bean crop production due tochemical control and, according to FAO, represent around 20-40% of bean crop losses along with other insect pests (Marrero, 2002). Over a broad geographic range, yield reductions between 10 and 40% have been reported (Giesler, 2002). Organic farmers rely on biological control for managing most insect pests, but there are no known natural enemies of the bean leaf beetle (Delate, 2001). They also feedon tender leaves, flowers and pods, which translates into a producer’s need for constant monitoring of insect populations.
Algae extract contains small amounts of nitrogen, potassium and phosphorus, trace metals and plant growth regulators (Abetz, 1983) which have been shown to act as a plant biostimulant, fertilizer, overall plant vigorizer and soil conditioner. The beneficial effect of algaeextract on enhancing the biosynthesis and translocation of carbohydrate could result in improving quality and advancing fruit maturity (Moniem, 2008). It has also been shown that algae extract applied foliarly to crops enhances and promotes greater yields as well as pest and disease tolerance and may contribute to insect control of organic crops. Constituents of seaweed, including betaines, caninduce systemic acquired resistance within the plant to various stress situations, including pest and disease attack (Growth, 2007). However, there are no reports that indicate the effects of algae extract on Ceratoma trifurcata in infested fields of cowpea or any other leguminous crop for which these insects are considered common pests. This experiment studies the effects of foliarly applied...