Leaf reddening disease of pineapple in Ghana

Abstract

A disease of pineapple, which threatens production of the exportable Smooth Cayenne pineapple, is reported. The disease has been observed in several commercial plantings in the Akwapim South, Ga and Gomoa districts, respectively, in the Eastern, Greater Accra and Central regions of Ghana. Reddening of the leaves (often interspersed with diffuse, irregular chlorotic patches), leaf dieback and plastic-like leaf consistency are the major above-ground symptoms. Diseased plants have reduced root systems, but internal browning of the underground stem is absent, indicating non-involvement of vascular wilt organisms, which have so far not been isolated from such plants. Mealybugs and ants are sometimes, but not always, associated with diseased plants. Nematodes of the genera Pratylenchus, Aphelenchus and Helicotylenchus have been recovered, though infrequently, from roots and root zone soil of diseased plants. Based on these preliminary results and field observations, it is hypothesized that the new disease of pineapple in Ghana could be of complex etiology with nematodes perhaps constituting one major group of primary causal agents and stress factors (e.g. soil moisture stress, low soil fertility and weed competition) being either primary agents or pre-disposing factors. Ongoing studies seek to conclusively determine the etiology of the disease as well as some factors affecting its epidemiological development. Until this is done, it is proposed that the disease be simply referred to as "red leaf disease" of pineapple after its dominant and most readily recognized symptom. Control measures for the disease are much needed if production of pineapple for export is to be sustained. To the author's knowledge, this is the first-published, detailed account of a disease of this nature in Ghana.