International Journal of Plant & Soil Science 15(6): 1-10, 2017; Article no.IJPSS.33086 ISSN: 2320-7035 Host Efficiency of Scutellonema bradys in Yam Companion Crops in Nigeria O. A. Kayode 1 and A. O. Claudius-Cole 1* 1Department of Crop Protection and Environmental Biology, University of Ibadan, Nigeria. Authors’ contributions This work was carried out in collaboration between both authors. Author AOCC designed the study experiments and wrote the protocol, author OAK conducted the research, managed the analyses of the study and wrote the first draft of the manuscript. Both authors read and approved the final manuscript. Article Information DOI: 10.9734/IJPSS/2017/33086 Editor(s): (1) Surendra Singh Bargali, Department of Botany, DSB Campus, Kumaun University, Nainital, Uttarakhand, India. Reviewers: (1) Bing-Lan Liu, Chaoyang University of Technology, Taiwan. (2) Atti Tchabi, University of Lomé, Togo. Complete Peer review History: http://www.sciencedomain.org/review-history/18967 Received 29 th March 2017 Accepted 24 th April 2017 Original Research Article th Published 8 May 2017 ABSTRACT Aim: Fourteen plants associated with the cultivation of yam in Nigeria were assessed for host suitability to S. bradys. Methodology: Cowpea, cassava, eggplant, fluted pumpkin, melon, maize, hot pepper, okra, water leaf, Mexican sunflower, tridax, peuro, and siam weed were inoculated with 5000 S. bradys individuals in sterilized or unsterilized soil. The experiment was a 3 x 14 factorial, laid out in a randomized complete block design (RCBD). Data were analyzed using ANOVA and means were separated using Fishers Least Significant Difference (LSD) at 5% level of probability. Results: Based on the number of S. bradys recovered from the soil and root symptoms, cowpea and yam were found to be good hosts to S. bradys with reproductive factor ≥ 2, while fluted pumpkin, okra, melon and eggplant were moderate hosts with reproductive factor ≥ 1. Maize, puero, hot pepper, waterleaf, Mexican sunflower, siam weed were non-host to S. bradys with reproductive factor ≤ 1. Conclusion: maize, puero and hot pepper are non hosts of S. bradys and could be intercropped with yam to reduce nematode populations and help to minimizing to the use of nematicides for S. bradys management in the yam cropping systems. _____________________________________________________________________________________________________ *Corresponding author: E-mail: [email protected], [email protected]; Kayode and Cole; IJPSS, 15(6): 1-10, 2017; Article no.IJPSS.33086 Keywords: Dioscorea; host efficiency; intercrops; Scutellonema bradys. 1. INTRODUCTION 2. MATERIALS AND METHODS The warm tropical climate and heavy rains 2.1 Experimental Site and Treatments promote the multiplication and spread of pest and diseases almost all the year round. Among The experiment was conducted in the such pests are the plant-parasitic nematodes. screenhouse of the International Institute of Nematode pests are of significant importance [1] Tropical Agriculture (IITA) main station at Ibadan among the various constraints to production of (7º31 Ń and 3º54 ́E), south western Nigeria. The yam. In West Africa, the yam nematode, following plants were evaluated; cowpea (Ife Scutellonema bradys , cause of the decay of yam brown) ( Vigna unguiculata L), egusi melon tubers known as “dry rot disease” [2]. (Citrullus lanatus L. ), okra ( Abelmoschus Scutellonema bradys is found in the peridermal esculentus L), eggplant ( Solanum melognena L), and subperidermal layers, rarely penetrating cassava (cv TZE 419) ( Manihot esculentus deeper than 1 or 2 cm during growth of the tuber. Crantz), hot pepper ( Capiscum frutescens L), Mexican sunflower ( Tithonia diversifolia (Hemsl.) Yam has the potential for meeting the hunger A. Gray), puero (Pueraria phaseoloides (Roxb.) problems of many people in sub Saharan Africa, Benth.), water leaf ( Talinium triangulare L.) its production and management, therefore, need Rohrb), tridax daisy ( Tridax procumbens L), siam to be sustainable. The management of pests weed ( Chromolaena odorata L.) King & H.E. threatening productivity of yams contributes to its Robins), yam ( Dioscorea rotundata sustainable production. S. bradys induce a (Poir.) J.Miège), fluted pumpkin ( Telifera significant reduction in the quality, marketable occidientales Hook. F.), maize (cv Oba super 1) value and edible portions of tubers. These (Zea mays L.). The seeds of maize, cowpea, reductions are more severe in stored yam [3]. puero, yam sett and cassava cuttings Effective management with chemical nematicides were obtained from IITA, while seeds of egg is possible [4], however, the high cost, their non- plant, hot pepper, and okra were obtained from a availability at the time of need and the hazards local seed store and weed seeds were obtained they pose as environmental pollutants from field plots. The treatments included naturally discourage most potential users in Nigeria [5]. infested S. bradys field soil, sterilized soil The use of rotation or intercropping of suitable inoculated with 5000 adults and juveniles S. crops can effectively reduce nematode bradys , uninoculated sterilized soil (control) all population, however, the intercropping practices filled into 10 kg capacity pots respectively. employed by many farmers is complicated by the Naturally infested field soil was collected from presence of three to four crops growing with yam plots in which yams with high dry rot damage in the same season [6]. were recently harvested while top soil to be sterilized was collected from fallow fields. The Population of S. bradys can build up in root of experiment was laid out in a randomised some weed host in the absence of yams and it complete block design (RCBD) with three can also survive in low populations in soil even in S. bradys applications (naturally infested field the absence of its hosts, which can serve as soil, artificially infested soil and sterilized control inoculum for next yam crop [7]. This causes soil) and fourteen plants, in four replicates. The reduction in size and quality of yam produced on plants were sown in ten-litre pots, irrigated on infected soil and may result in the destruction of alternate days and kept free of weeds. the yam tubers [8]. The development of complimentary strategies that are reliable, practicable, and economically justified to lower 2.2 Source of Inoculum and Extraction of nematode damage to meet farmers’ income and Scutellonema bradys from Tubers nutrition needs is necessary. A suitable crop rotation scheme can contribute to effective Yam tubers showing advanced symptoms of dry control of S. bradys (dry rot), but this will require rot, obtained from IITA yam barn and yam stores information on the host status of various plants served as source of inoculum. The S. bradys - commonly associated with yams in the field. This infected yam tubers were peeled and the peels study was designed to assess weeds and crops cut into small (1 x 0.5 cm) pieces. S. bradys was commonly associated or intercropped with yams extracted from the infested tubers using the for their host status to S. bradys . modified Baermann funnel method [9]. The set- 2 Kayode and Cole; IJPSS, 15(6): 1-10, 2017; Article no.IJPSS.33086 up consisted of plastic sieves, shallow trays and populations; Pi is the initial nematode population double-ply tissue paper. Plastic sieves, lined with (5,000 for the inoculated soil and 3,200 for the two-ply tissue paper were placed in shallow trays naturally infested soil). Host plant efficiency (25 cm diameter) separately. Chopped tuber rating based on reproductive factor using a tissues were spread carefully and evenly over modification of the method of Loveys and Bird the tissue paper. Water was carefully and slowly [10]; RF ˃3 = Very good host; RF 2-3 = Good added to each tray until the samples were host; RF 1-2 = Moderate; RF ˂ 1= Poor host; non submerged. The set-up was left undisturbed in entry of nematode into root = Non- host. the laboratory for 48 hrs. The nematode-water suspension, after removing the sieves, was Nematode counts were transformed using the poured into beakers and was concentrated after square root (x + 0.5) transformation method to 24 hrs by decanting 70% of the supernatant. normalize the data. [11]. Data were submitted to Analysis of Variance (ANOVA) using SAS 2.3 Estimation of Inoculum and Ino- statistical package (12). Means were separated culation using Fishers Least Significant Difference (LSD) at 5% level of probability. The number of nematodes per ml of the suspension was determined by counting from 3. RESULTS AND DISCUSSION three aliquots of 2 ml each under a dissecting microscope. The number of S. bradys per ml was 3.1 Growth of Yam Companion Crops in used to extrapolate the volume of suspension Response to Scutellonema bradys that will carry 5000 S. bradys required for inoculation. The suspension of inoculum was There were no significant differences in plant applied to the appropriate treatments 28 days height among treatments for siam weed, hot after planting using a syringe into four 1–cm pepper, water leaf, and tridax daisy (Fig. 1a). holes made in the soil close to the seedlings. Soil Water leaf, yam and fluted pumpkin plants extraction was carried out to determine the growing in field soil were taller than in sterilized quantity of nematodes in the naturally infested inoculated pots, uninoculated cowpea, eggplant, field soil. This was achieved by thoroughly mixing cassava and okra were significantly taller ( P = 3 all the soil and collecting five samples of 250 cm .05) than the S. bradys infested plants. Mexican each. The modified pie-pan method was used for sunflower growing in field soil were significantly nematode extraction over 48 hours. The number (P = .05) shorter that other treatments. of S. bradys per sample was averaged and calculated per pot as initial population (Pi = There were significantly more leaves ( P = .05) in 3200) for the treatment. The experiment was cowpea, okra, puero, maize, eggplant, melon terminated at twelve weeks after inoculation. A and tridax daisy growing in pots with no S.