Evaluation of Animal Dungs and Organomineral Fertilizer for the Control of Meloidogyne incognita on Sweet Potato

Hindawi Publishing Corporation International Journal of Agronomy Volume 2015, Article ID 725363, 5 pages http://dx.doi.org/10.1155/2015/725363 Research Article Evaluation of Animal Dungs and Organomineral Fertilizer for the Control of Meloidogyne incognita on Sweet Potato Oluremi Solomon Osunlola1 and Bamidele Fawole2 1 Department of Crop Production, Kwara State University, Malete, PMB 1530, Ilorin, Nigeria Department of Crop Protection and Environmental Biology, University of Ibadan, Ibadan, Nigeria 2 Correspondence should be addressed to Oluremi Solomon Osunlola; Received 28 September 2015; Revised 3 December 2015; Accepted 10 December 2015 Academic Editor: David Clay Copyright © 2015 O. S. Osunlola and B. Fawole. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Root-knot nematode, Meloidogyne incognita, is an important animate pathogen causing major damage and severe reductions in the growth, yield, and quality of sweet potato. Nematicides are expensive and their application also causes environmental pollution. A field experiment was therefore conducted to evaluate the effectiveness of poultry dung (10 or 20 t/ha), cow dung (10 or 20 t/ha), horse dung (10 or 20 t/ha), goat dung (10 or 20 t/ha), organomineral fertilizer (2 or 4 t/ha), and carbofuran (3 kg a.i/ha) in the management of M. incognita on sweet potato using a randomized complete block design. The unamended plots served as control. Data were analysed using ANOVA (𝑝 ≤ 0.05). All organic materials and carbofuran significantly (𝑝 ≤ 0.05) reduced nematode reproduction and root damage compared with control. Poultry dung (10 and 20 t/ha) and carbofuran were, however, more efficient in nematode control than other organic materials. Sweet potato plants that were grown on soil treated with organomineral fertilizer had the highest mean number of vines and fresh shoot weight, while poultry dung improved sweet potato quality and yield. It is therefore recommended that the use of poultry dung be employed in combination with other nematode control strategies to achieve sustainable, economic, and environment-friendly nematode management. 1. Introduction Sweet potato (Ipomoea batatas L. Lam) is a dicotyledonous crop that belongs to the family Convolvulaceae. It is the world’s second most important root and tuber crop after potato [1]. Sweet potato is normally cultivated for its large, starchy, sweet-tasting tuber which is primarily used as food stuff and is often boiled, fried, roasted, baked, canned, or fermented for human consumption [2, 3]. It is also used to produce flour for bread and pastry making [4]. Different kinds of products such as edible and fermentable syrups, industrial alcohol, dye, acetone, lactic acid, vinegar, yeast, pie fillings, purees, candied pieces, soufflés, and baby foods are made from sweet potato [5]. Sweet potato has also been used as a laxative and antidiabetic and in the treatment of low fever and skin diseases [5]. Root-knot disease caused by rootknot nematodes, Meloidogyne spp., is a well known disease of many tropical and subtropical crops. Meloidogyne incognita is the most important nematode pest of sweet potato which occurs in most sweet potato growing regions where it causes severe damage [6, 7]. Symptoms of M. incognita infection include patchiness in field, stunting, wilting, chlorosis, and galling of the root system. Galls are, however, not usually well-developed on tubers, but the obvious symptoms on tubers are longitudinal cracks and blister-like bumps [8]. M. incognita has been implicated in yield reduction of sweet potato by earlier workers. Losses between 20 and 83.2% have been reported by earlier workers [9–12]. Although the use of nematicides has been found to be effective for nematode control, due to high toxic residual effect of chemicals on environment, particularly on nontarget organisms [13], there is a need to develop alternative nematode control measures. Earlier workers have reported the effectiveness of different materials like plant manures, plant extracts, and animal manures in nematode management and consequent improved crop growth and yield [14–16]. The objective of this study was to evaluate poultry, cow, goat, and horse dungs and organomineral fertilizer in the management of M. incognita and assess their effects on the growth, yield, and quality of sweet potato in the field. 2 2. Materials and Methods The experiment was carried out in 2009 and 2010 cropping seasons on a piece of land that was naturally infested by Meloidogyne incognita in the Crop Garden of the Department of Crop Protection and Environmental Biology, University of Ibadan, Ibadan. Three months before the commencement of the experiment, the nematode was multiplied under Celosia argentea to augment the field population. The piece of land was divided into seven equal blocks and each block was further divided into twelve equal plots measuring 2.5 × 2.5 m each. There was a spacing of 1 m between the blocks and 0.5 m between plots. Soil samples were collected in a zigzag manner from each plot four days before planting. Nematodes were extracted from the soil samples using the method of Whitehead and Hemming [17]. The root-knot nematode juveniles (𝐽2 ) extracted were counted under a stereoscope after 48 hours in a counting dish. The animal dungs used in the study were collected from the Teaching and Research Farm of the University and were air dried for three weeks before use. Organomineral fertilizer was obtained from the Department of Agronomy, University of Ibadan, while carbofuran was purchased from an agrochemical shop in Ibadan. The plots were thereafter treated with air-dried poultry manure, goat manure, cow manure, and horse manure each at two rates: 10 t/ha and 20 t/ha; organomineral fertilizer at two rates: 2 t and 4 t/ha; carbofuran at 3 kg a.i/ha, and untreated plots served as control. Three weeks after the application of the organic materials and chemical, vine cuttings of M. incognita susceptible sweet potato cultivar (CV TIS 4400-2) [18] were planted to each plot. The experiment was laid out in a randomized complete block design with twelve treatments in seven replicates. The plants were rain fed as the experiment was carried out during the raining seasons. The experimental plot was kept weed-free by regular hoeing. The plants were harvested five months after planting and the root systems were rated for root damage (gall index) on a scale of 0–5 where 0 equals no gall; 1 equals 1–20% of the root system galled; 2 equals 21– 40% of the root system galled; 3 equals 41–60% of the root system galled; 4 equals 61–80% of the root system galled; and 5 equals 81–100% of the root system galled [19]. Similarly, data were taken on number of vines per plant, fresh shoot weights (g), fresh root weights (g), number of tubers, and (...truncated)