Efectividad de herbicidas preemergentes en el combate de malezas en vivero de macadanfla (Macadanda integrifolia)
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Herrera Murillo, Franklin
Herrera, Mario
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Universidad de Costa Rica
Abstract
En un vivero comercial de la finca “Macadamia San Gregado”, en la Fortuna de San Carlos, Alajuela, Costa Rica, se efectuó un experirnento con el propósito de determinar costos en el control de malezas, selectividad a la macadamia sembrada en bolsas de polictileno y efectiviclid en el combate de malezas, de dosis de oxifluorfén granulado y de combinaciones promisorias de herbicidas preemergentes, para minimizar la competencia de las malezas con la macadamia durante la fase de vivero. El periodo experimental fue de setiembre de 1991 a octubre de 1992. La aplicación de los herbicidas se inició a las 12 semanas después del transplante (12 SDT). Los tratamientos evaluados en un diseñó de Bloques Completos al Azar fueron: oxfluorfén 0,0050, 0,010 y 0,015 g/bolsa (12 SDT); simazina 1,5 kg /ha (12 SDT) + oxifluorfén 0,0050 g/bolsa (24 SDI); simazina 1,5 kg/ha (12 SEIT) + simazina 1,5 kg/ha (24 y 40 SDT); terbutilazina 1,5 kg/ha (12 SDT) + oxifluorfén 0,0050 g/bolsa (26 SDT); Deshierbas manuales a las 12, 18, 24, 34 y 40 SDT; y un testigo enmalezado. La aplicación del oxifluorfén granulado se hizo en forma manual, mientras que los líquidos, con un equipo accionado a presión constante por C02 y dirigido a la base de las plantas. Se encontró que el oxifluorfén granulado en las tres dosis evaluadas, mantuvo un porcentaje de control de malezas en general superior al 80 % mientras que con simazina o terbutilazina, fue necesario recurrir a otras aplicaciones para el porcentaje de cobertura de malezas por debajo de un 20 %. La deshierba manual fue la alternativa de control de malezas de mayor uso de mano de obra; mientras que a excepción del testigo enmalezado, el oxifluorfén 0,005 g/bolsa redujo el empleo de mano de obra en un 53% comparado con las deshierbas. La competencia por malezas hizo que los árboles de macadamia debieran permanecer cinco semanas mas en vivero pira alcanzar el tamaño necesario para nierto; por lo cual, todos los tratamientos de control de malezas dieron un cambio positivo en el ingreso neto. Ninguno de los herbicidas evaluados causó daños a la macadamia.
An experiment was conducted, at a commercial nursery in Fortuna de San Carlos, Alajuela- Costa Rica, to determine the costs of controlling weeds, the selectivity to macadamia rootstalks planted in polyethylene bags and the weed control effectiveness of doses of granulated oxyfluorfen and mixtures of promissing pre-emergent herbicides to minimize weed competence with the macadamia, during the nursery Phase. The experimental period was from September 1991 to October 1992. The herbicides' application started 12 weeks after the macadamia treeswere transplanted (12 wat). The treatments evaluated, with a Complete Randomized Block design, were: oxyfluorfen at the rates of 0.005, 0.01 and 0.015 g/bag (12 wat), simazine at 1.5 kg/ha (12 wat) + oxyfluorfen at 0.005 g/bag (24 wat), simazine at 1.5 kg/lia (12 wat) + simazine at 1.5 kg/ ha (24 and 40wat), terbutylazine at 1.5 kg/ha (12wat) + oxyfluorfen at 0.005 g/bag (26 wat), hand weeding at 12,18,24,34 and 40 wat, and an unweeded control. The granulated oxyfluorfen was spreaded by hand while the liquid treatments were applied with a C02 operated sprayer. It was found that oxyfluorfen, at the tested doses, maintained a general weed control percentage over 90 % during the whole macadamia nursery cycle. With simazine and terbutylazine it was necessary to make other apilications in order to keel) the weed coverage under 20 %. The hand weeding was the largest use of hand labor, while the oxyfluorfen at 0.005 g/bag lowered the costs and the use of hand labor by 33 and 53 %, respectively. The three simazine applications reduced the costs by 44 %, although it only released hand labor by 46 %. Due to the weed competence, it was necessary to keep the macadamia trees a longer period of time in the nursery, before they could be grafted. None of the tested herbicides caused damage to the macadamia.
An experiment was conducted, at a commercial nursery in Fortuna de San Carlos, Alajuela- Costa Rica, to determine the costs of controlling weeds, the selectivity to macadamia rootstalks planted in polyethylene bags and the weed control effectiveness of doses of granulated oxyfluorfen and mixtures of promissing pre-emergent herbicides to minimize weed competence with the macadamia, during the nursery Phase. The experimental period was from September 1991 to October 1992. The herbicides' application started 12 weeks after the macadamia treeswere transplanted (12 wat). The treatments evaluated, with a Complete Randomized Block design, were: oxyfluorfen at the rates of 0.005, 0.01 and 0.015 g/bag (12 wat), simazine at 1.5 kg/ha (12 wat) + oxyfluorfen at 0.005 g/bag (24 wat), simazine at 1.5 kg/lia (12 wat) + simazine at 1.5 kg/ ha (24 and 40wat), terbutylazine at 1.5 kg/ha (12wat) + oxyfluorfen at 0.005 g/bag (26 wat), hand weeding at 12,18,24,34 and 40 wat, and an unweeded control. The granulated oxyfluorfen was spreaded by hand while the liquid treatments were applied with a C02 operated sprayer. It was found that oxyfluorfen, at the tested doses, maintained a general weed control percentage over 90 % during the whole macadamia nursery cycle. With simazine and terbutylazine it was necessary to make other apilications in order to keel) the weed coverage under 20 %. The hand weeding was the largest use of hand labor, while the oxyfluorfen at 0.005 g/bag lowered the costs and the use of hand labor by 33 and 53 %, respectively. The three simazine applications reduced the costs by 44 %, although it only released hand labor by 46 %. Due to the weed competence, it was necessary to keep the macadamia trees a longer period of time in the nursery, before they could be grafted. None of the tested herbicides caused damage to the macadamia.
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Keywords
Macadamia ternifolia, nuez de macadamia, viveros, herbicidas, malezas, Costa Rica, Macadamia ternifolia, macadamia nuts, plant nurseries, herbicides, weeds, Costa Rica