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Digestibility, protein content, and nutrient yields of alfalfa stressed by selected early season insect pests and diseases

by Godfrey, L.D; Yeargan, K.V; Muntifering, R.B.
Subject(s): PLANTAS FORRAJERAS | ALFALFA | VALOR NUTRITIVO | RENDIMIENTO | SITONA HISPIDULUS | HYPERA POSTICA | INSECTOS DANINOS | PERDIDAS | MATERIA SECA | ANALISIS ECONOMICO | FEED CROPS | LUCERNE | NUTRITIVE VALUE | YIELDS | SITONA HISPIDULUS | HYPERA POSTICA | PEST INSECTS | LOSSES | ECONOMIC ANALYSIS | PLANTE FOURRAGERE | LUZERNE | VALEUR NUTRITIVE | RENDEMENT | SITONA HISPIDULUS | HYPERA POSTICA | INSECTE NUISIBLE | PERTE | ANALYSE ECONOMIQUE In: Journal of Economic Entomology (EUA) v. 80(1) p. 257-262Summary: A field study to examine effects of three early season alfalfa pests on forage nutrient quality and nutrient yield was conducted from 1981 to 1983. Eight treatments with all possible combinations of clover root curculio (CRC), Sitona hispidulus (F.); alfalfa weevil (AW), Hypera postica (Gyllenhal); and soil-borne root-rot fungi (FU) were replicated in field plots. CRC larval feeding reduced first-harvest percentage crude protein content by ¥1.07 percent. Also, crude protein (CP) values were decreased in second and third harvests, in response to earlier CRC presence. AW and FU presence had minimal adverse impact on protein levels. In the first harvest, in vitro digestibility was reduced by AW larval feeding from 63.74 to 61.39 percent; the other two pests had no significant effects. Pests stresses significantly reduced yields of CP and in vitro digestible dry matter. These losses resulted from reductions of dry-matter yields but were intensified by losses of nutrient content. An economic analysis showed that pest stresses reduced herbage value per metric ton based on nutrient content alone, by 5.00 and 2.63 in 1982 and 1983, respectively. Economic value per hectare, a combination of nutrient value and dry-matter reductions, showed losses of 187.53 in 1982 and 169.20 in 1983 from pest stresses
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A field study to examine effects of three early season alfalfa pests on forage nutrient quality and nutrient yield was conducted from 1981 to 1983. Eight treatments with all possible combinations of clover root curculio (CRC), Sitona hispidulus (F.); alfalfa weevil (AW), Hypera postica (Gyllenhal); and soil-borne root-rot fungi (FU) were replicated in field plots. CRC larval feeding reduced first-harvest percentage crude protein content by ¥1.07 percent. Also, crude protein (CP) values were decreased in second and third harvests, in response to earlier CRC presence. AW and FU presence had minimal adverse impact on protein levels. In the first harvest, in vitro digestibility was reduced by AW larval feeding from 63.74 to 61.39 percent; the other two pests had no significant effects. Pests stresses significantly reduced yields of CP and in vitro digestible dry matter. These losses resulted from reductions of dry-matter yields but were intensified by losses of nutrient content. An economic analysis showed that pest stresses reduced herbage value per metric ton based on nutrient content alone, by 5.00 and 2.63 in 1982 and 1983, respectively. Economic value per hectare, a combination of nutrient value and dry-matter reductions, showed losses of 187.53 in 1982 and 169.20 in 1983 from pest stresses

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