%0 Journal Article
%T Etiological and epidemiological studies on the red leaf disease of pineapple in Ghana
%A RT Awuah
%A E Adzim
%J African Crop Science Journal
%D 2004
%I 
%X Possible cause(s) of red leaf disease (RLD) of pineapple (Ananas comosus L.) in Ghana were examined through field observations, isolation of suspected organisms from roots of diseased plants, growing plants in potted steam-sterilised and unsterilised natural field soils. Others included detection of the pineapple closterovirus (PCV) from symptomatic and healthy pineapple leaves using tissue blot immunoassay (TBIA). Effects of soil moisture, soil fertility, sucker condition and light intensity on the disease were studied in pots while some factor combinations were studied in mini plots in the field. Diseased plants from the field had reduced root systems and had Neosartorya fischeri. Nematodes of the genera Aphelenchus, Pratylenchus and Helicotylenchus were recovered from roots and infrequently from the rind of the underground stem. Pineapple plants grown outdoors in steam-sterilised field soil reddened just as those grown in unsterilised soil. The PCV was detected in only 53% of all typically symptomatic leaves examined. All non-symptomatic leaves also tested positive for PCV. Plants grown from symptomatic suckers in a plant house with diffuse light intensity (7,440 lm m-2) and at 29 oC, recovered from RLD within 6 months. These plants, however, reddened when grown outdoors with intense light (39,751 lm m-2) at 30 oC. Significantly (P<0.05) lower disease levels were recorded on mini-plots optimally fertilised with NPK and maintained at high moisture than on low fertility, low moisture plots. In a further mini plot trial, plants grown with reduced light had lower disease levels than those grown with full light. Overall, these results show that soil biotic factors have no primary etiological role in RLD. The viral nature of the disease is also doubtful. Leaf reddening in pineapple could be a physiological response to environmental stresses. Key Words: Ananas comosus, nematodes, Neosartorya fischeri, mealybug wilt R¨¦SUM¨¦ Les possibles causes de la maladie des feuilles rouge (MFR) de l'anana (Ananas comosus L.) au Ghana ¨¦taient ¨¦tudi¨¦es ¨¤ travers des observations des champs, en isolation des organismes suspect¨¦s dans les racines des plantes infect¨¦es, en cultivant des plantes dans des p ts st¨¦rilis¨¦s par la vapeur et des champs naturels non st¨¦rilis¨¦s. D'autres m¨¦thodes incluaient la detection des closterovirus de l'anana (CVA) sur des feuilles d'anana pr¨¦sentant les sympt mes et en bonne sant¨¦ en utilisant des buvard immunoassay (BIA). Les effets de l'humidit¨¦ du sol, la fertilit¨¦ du sol, les conditions des rejetons et l'intensit¨¦ de la lumi¨¨re sur la maladie ¨¦taient ¨¦tudi¨¦s dans des p ts alors que certains facteurs des combinaisons ¨¦taient ¨¦tudi¨¦s dans des mini parcelles dans les champs. Les plantes infect¨¦es dans les champs avaient des syst¨¨mes des racines r¨¦duits et avaient Neosartorya fischeri. Les n¨¦matodes des genres Aphelenchus, Pratylenchus et le Helicotylenchus ¨¦taient r¨¦cup¨¦r¨¦s des racines et de mani¨¨re non reguli¨¨re des ¨¦corces de la part
%U http://www.ajol.info/index.php/acsj/article/view/27673