Management of Root-Knot Nematodes (Meloidogyne Spp) on Tomato using Antagonistic Plants

African marigold (Tagetes erecta) and Crotalaria juncea were used as intercrops to control root knot nematodes on a susceptible tomato cultivar, Ibadan local in a pot experiment at the roof top of Crop Protection and Environmental Biology Dept, University of Ibadan, Ibadan, Oyo State, Nigeria. Four weeks old tomato plants intercropped with African marigold (Tagetes erecta) and Crotalaria juncea were inoculated with 5000eggs of root knot nematodes. Results indicated that absence of marigold or Crotalaria plants in the inoculated treatments led to increase in the number of second stage juvenile of root knot nematodes. The antagonistic plants produced significant reduction (P<0.05) in the root gall indices, reproductive factor and final nematode population in susceptible tomato plants roots. However, no significant differences were observed across the treatments in terms of mean number of leaves and plant heights. The results obtained have important implications for the design of alternative nematode management strategies using antagonistic plants. Keywords: antagonistic plants, root-knot nematodes, Gall index, Reproductive factor

Maize Response to Sole and Combined Effects of Nitrogen and Nematode Stresses

Crops grown on the field or in phytotrons are faced with different biotic stresses including plant-parasitic nematodes (PPNs) and abiotic stresses such as drought and poor soil fertility (low nitrogen levels). In this study, the interactive responses of a low-nitrogen tolerant variety LNTP-YC6 and a regular variety BR-9928-DMRSR to Pratylenchus zeae under four nitrogen-levels: no amendment; [T0], low nitrogen [100kgN/ha NPK; T1], optimum nitrogen [200kgN/ha NPK + Urea; T2] and compost [10t/ha; T3] were investigated. The treatments were arranged in a 2 x 4 factorial fitted into randomised complete block design (RCBD) with four replicates. Data were collected on growth parameters (plant height and stem girth), yield components (number and weight of cobs), lesion score (LS), final nematode population (FNP) and reproductive factor (RF). Low nutrient stress in combination with nematode infection generally reduced maize growth and yield. Growth parameters of BR-9928-DMRSR variety were generally high while yield parameters of LNTP-YC6 variety were significantly greater than in BR-9928-DMRSR variety. However, T2 and T3 improved growth and yield of both maize varieties compared to T0, with T2 being superior to T3. Meanwhile, T3 reduced FNP more than T2. FNP (107.65) and RF (1.3) of P. zeae on LNTP-YC6 variety and with T3 was significantly low compared to T2 (178, 3.34), T0 (188, 3.6) and T1 (217, 5.0). In all the parameters considered, LNTP-YC6 outperformed BR-9928-DMRSR variety. In conclusion, soil amendment with optimum rate of nitrogen and compost reduced nematode population and enhanced maize growth, while low nitrogen in combination with nematode stress reduced maize yield

Effect of pre-plant treatments of yam (Dioscorea rotundata) setts on the production of healthy seed yam, seed yam storage and consecutive ware tuber production

Numerous pests and diseases of yams are perpetuated from season to season through the use of infected seed material. Developing a system for generating healthy seed material would disrupt this disease cycle and reduce losses in field and storage. The use of various pre-plant treatments was evaluated in field experiments carried out at three sites in Nigeria. Yam tubers of four preferred local cultivars were cut into 100 g setts and treated with pesticide (fungicide + insecticide mixture), neem extract (1 : 5 w/v), hot water (20 min at 53 °C) or wood ash (farmers practice) and compared with untreated setts. Pesticide treated setts sprouted better than all other treatments and generally led to lower pest and disease damage of yam tubers. Pesticide treatment increased tuber yields over most treatments, depending on cultivar, but effectively doubled the production as compared to the control. Pesticide and hot water treated setts produced the healthiest seed yams, which had lower storage losses than tubers from other treatments. These pre-treated seed yams produced higher yields corresponding to 700 % potential gain compared to the farmers usual practice. Treatments had no obvious influence on virus incidence, although virus-symptomatic plants yielded significantly less than nonsymptomatic plants. This study demonstrated that pre-plant treatment of setts with pesticide is a simple and effective method that guarantees more, heavier and healthier seed yam tubers

Plant-Parasitic Nematodes and Food Security in Sub-Saharan Africa

Article purchasedSub-Saharan Africa (SSA) is a region beset with challenges, not least its ability to feed itself. Low agricultural productivity, exploding populations, and escalating urbanization have led to declining per capita food availability. In order to reverse this trend, crop production systems must intensify, which brings with it an elevated threat from pests and diseases, including plant-parasitic nematodes. A holistic systems approach to pest management recognizes disciplinary integration. However, a critical under-representation of nematology expertise is a pivotal shortcoming, especially given the magnitude of the threat nematodes pose under more intensified systems. With more volatile climates, efficient use of water by healthy root systems is especially crucial. Within SSA, smallholder farming systems dominate the agricultural landscape, where a limited understanding of nematode problems prevails. This review provides a synopsis of current nematode challenges facing SSA and presents the opportunities to overcome current shortcomings, including a means to increase nematology capacity