IDENTIFICATION, PATHOGENICITY AND MANAGEMENT OF FUNGI ISOLATED FROM CASTOR (Ricinus communis L.) IN SAMARU, NIGERIA

  • : Ms Word, Ms Word Format
  • : 76 Pages
  • : ₦3,000 | $25 | ₵60 | Ksh 2720
  • : 1-5 Chapters
  •  
  • Click to DOWNLOAD Materials

IDENTIFICATION, PATHOGENICITY AND MANAGEMENT OF FUNGI ISOLATED FROM CASTOR (Ricinus communis L.) IN SAMARU, NIGERIA

Abstract:

The fungi isolated from infected castor leaves were Fusarium sp, Helminthosporium sp and Curvularia sp. Pathogenicity tests was conducted on the fungi and Fusarium sp was pathogenic on castor and its pathogenicity was confirmed using Koch’s postulate. The Fusarium sp was later identified to be Fusarium pallidoroseum by International Mycological Institute (IMI) Egham, London. Plants at different ages (11, 18 and 25 days old) were inoculated using three methods (spray, smear and soil inoculation). Twenty one day old castor plants were inoculated with inoculum at different densities (103, 105, 107, 1010 conidia / ml and water) and assessed in order to determine at what density the pathogen can induce infection. Six fungicides were evaluated in vitro at three concentrations (one and half the recommended, recommended and half recommended rates) for their effect on growth and regrowth of mycelia, sporulation and conidia size of Fusarium pallidoroseum. Five of the fungicides tested in the laboratory were further evaluated at two concentrations (recommended and half recommended rates) for their efficacy in the management of leaf blight induced by Fusarium pallidoroseum in vivo. Effect of three sowing dates on disease incidence and severity was assessed on two castor types during the 2006 wet season. During the pathogenicity tests it was observed that, younger plants were more susceptible to infection than older plants. For the in vitro evaluation of fungicides, it was observed that all the fungicides (benomyl, benomyl + thiram, mancozeb, metalaxyl-M + thiomethoxam + difenoconazole, tricyclazole and carbendazim + mancozeb) at all the concentrations tested inhibited mycelial growth, sporulation, and reduced conidia size and mycelial regrowth of the fungus. Benomyl, benomyl + thiram and tricyclazole completely inhibited mycelial growth and sporulation of the fungus at the three tested rates. Metalaxyl-M + thiomethoxam + difenoconazole, carbendazim + mancozeb inhibited mycelial growth and sporulation only at one and half rate but not at recommended and half recommended rates. Inhibitory effect of all the fungicides on mycelial growth and sporulation were greatest at one and half recommended rate. Benomyl, benomyl + thiram, mancozeb, carbendazim + mancozeb and tricyclazole reduced the rate of disease development on 21 – day- old inoculated castor plants in the screenhouse at recommended than at half the recommended rate. Large seeded castor sown on July 27 had less disease severity and higher yield compared with plants sown in August 3 and August 11. For the small seeded type, August 3 sown plants had high disease severity and more yield than those sown on other dates. F. pallidoroseum is the cause of leaf blight, seedling rot and wilt of castor in Samaru. The younger plants (11 days old) were more susceptible to infection. The evaluated fungicides can be used to control F. pallidoroseum on castor. Sowing late, resulted in poor seed germination thereby affecting bean yield negatively.

IDENTIFICATION, PATHOGENICITY AND MANAGEMENT OF FUNGI ISOLATED FROM CASTOR (Ricinus communis L.) IN SAMARU, NIGERIA

Sharing is caring!

Leave a Reply