Nigerian Journal of Agriculture, Food and Environment. 8(4):64-69 Published December, 2012 Aliyu et al., 2012 NJAFE VOL. 8 No. 4, 2012 64 EFFECT OF PYTHIUM APHANIDERMATUM ON TWO CULTIVARS OF PEPPER (Capsicum spp) Aliyu, T. H., Balogun, O. S., and Adesina, O. M. ABSTRACT Department of Crop protection, Faculty of Agriculture, University of Ilorin, P.M.B 1515 Ilorin- Nigeria. Email of Corresponding Author: aliyutaiyehussein@yahoo.com, Telephone: +2348030472667 A potted experiment was carried out to study the effect of Pythium aphanidermatum on two cultivars of pepper [NHVI B (improved variety) and Sombo (local variety)]. 24 pots of sterilized soil were used and four seeds of each pepper variety were planted in 12 pots each. The plants were inoculated by drenching at planting (pre-emergence) and 2weeks later (post- emergence) and non-inoculated plants served as control. The inoculum was pure isolates of P. aphanidermatum, obtained from sub-culturing colonies of the fungus that was growing on infected okra root tissues. Data were collected for growth and yield indices. The data were subjected to analysis of variance (ANOVA) and significant differences determined at P < 0.05. The results showed that there were significant differences in the growth and yield parameters between the inoculated and the control plants, with the inoculated plants having lower values. Pre-emergence inoculation appeared to be more effective than post-emergence inoculation in inducing disease response in plants. The improved variety NHVI B generally performed better than the local variety. The results suggest that prevention of early fungi infection and the availability of disease resistant cultivars could be the best control strategies in reducing the diseases caused by Pythium spp on pepper. Keywords: Pythium aphanidermatum, Pepper cultivar, Pre-emergence, Post-emergence, Inoculation. INTRODUCTION Peppers are vegetable crops belonging to the family Solanaceae and genus capsicum, which are native to tropical America and Africa. The family consists of about 90 genera and nearly 3000 species (Vidyarth and Tripatha 2002). Chillis and other specie come from the bushy capsicum species and white or black pepper come from climbing vine, Piper nigrum (Vaughan and Geissler, 2009). It is generally believed that about 20 capsicum species are distributed worldwide out of which Capsicum annum,Ccapsicum frutescens, Capsicum chinense,Ccapsicum pendulum and Capsicum pubescens are the five major species cultivated (Saikat and Amit, 2003). Capsicum species is among the world’s most popular vegetable and is being used mainly as spices and condiments. It is an important spice crop that is produced and consumed either fresh or processed (Sonago, 2003). Some varieties are very hot (the chilli and cayenne pepper) and are normally used as a pungent flavouring whilst milder varieties (the sweet pepper) have a very pleasant flavour with a slight sweetness and are often eaten raw in salads (Brouk, 1975). Capsicum frutescens contain about 85.7% moisture, 4.35% ash, 11.7% crude protein, 12.7% crude fat, 9 – 17% crude fibre and 62.94% carbohydrate. They are rich in mineral elements such as Sodium, Calcium, Iron, Phosphorus, Potassium, Zinc, Copper, Cobalt, Manganese, Sulphur and Magnesium (Mehnet et al., 2006) and also have good quantities of vitamins E, B 1, B 2 , B 3 , B 5 , B 6 , C Carotene and folate (USDA, 2008). Pepper is an important vegetable consumed by human beings in Nigeria and is mainly grown around the savannah ecological zones as a crop mixture or mono crop both during the rainy season and dry season under irrigation (Denton et al., 2000). It is also used in fresh form or as paste, pure and juice or ground with other vegetables in the preparation of stew and soup (NAERLS). Diseases are major constraints to pepper production in sub-Saharan Africa (Nsabiyera et al., 2012). The major limiting diseases of most peppers in Sub-Sahara Africa and elsewhere are phyto-pathogenic fungi, bacteria, and viruses (Melanie and Sally, 2004). Attacks by fungal, bacterial or viral diseases, nematodes, mites and many insect pest infestations infections can cause significant losses in pepper production (Ochoa-Alejo and Ramirez- Malagon, 2001). Pythium is one of the most important root and seedling pathogens in greenhouses, on both vegetables and horticultural crops (Paulitz and Belanger 2001). Pythium aphanidermatum is a soil borne plant pathogen in a genus in the class Oomycetes, which are also known as water moulds (Sutton et al., 2006). Root browning is a principle symptom of Pythium root rot, which is a destructive disease of peppers (Moorman 2002; Owen-Going et al., 2003). The root browning, marks the development of the necrotrophic phase of the disease, which is associated with abrupt decline in the growth rate of the roots and foliage of affected pepper plants (Sutton et al., 2006). The disease development of P. aphanidermatum is still rather unpredictable (Postma et al., 2001). Rapid germination of sporangia of Pythium after exposure to exudates or volatiles from seeds or roots (Osburn et al., 1989) followed by immediate infection makes management of the pathogen very difficult (Whipps and Lumsden, 1991). Although fungicides have shown promising results in controlling the damping-off disease, phytotoxicity and fungicide residues are major problems leading to environmental pollution and human health