Leaf reddening disease of pineapple in Ghana

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 Centralregions 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 undergroundstem 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 andHelicotylenchus 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 ofpineapple 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) beingeither 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 isproposed 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, thisis the first-published, detailed account of a disease of this nature in Ghana

A subset of platinum-containing chemotherapeutic agents kills cells by inducing ribosome biogenesis stress

Cisplatin and its platinum analogs, carboplatin and oxaliplatin, are some of the most widely used cancer chemotherapeutics. Although cisplatin and carboplatin are used primarily in germ cell, breast and lung malignancies, oxaliplatin is instead used almost exclusively to treat colorectal and other gastrointestinal cancers. Here we utilize a unique, multi-platform genetic approach to study the mechanism of action of these clinically established platinum anti-cancer agents, as well as more recently developed cisplatin analogs. We show that oxaliplatin, unlike cisplatin and carboplatin, does not kill cells through the DNA-damage response. Rather, oxaliplatin kills cells by inducing ribosome biogenesis stress. This difference in drug mechanism explains the distinct clinical implementation of oxaliplatin relative to cisplatin, and it might enable mechanistically informed selection of distinct platinum drugs for distinct malignancies. These data highlight the functional diversity of core components of front-line cancer therapy and the potential benefits of applying a mechanism-based rationale to the use of our current arsenal of anti-cancer drugs

Beneficial effects of bending maize plants at physiological maturity on lodging and on some pre-harvest grain quality parameters

In the study, maize plants (cv. Aburotia) bent, just below the lowest ear, at 2 weeks before physiological maturity (PM), at PM, and 2 weeks after PM were compared with unbent plants for grain moisture content, cob infestation with insects (adults and larvae), grain mouldiness, grain yield per cob, and incidence of lodging. The bending and no bending treatments were applied in a randomized complete block design with three replications. Relevant weather records during the study period were provided by the Kumasi Meteorological Station. Grain moisture content, cob infestation with adult insects, and extent of lodging were, at harvest, significantly lower (P=0.05) in bent plants than in unbent ones. Among the bent plants, these parameters decreased with early bending. Moisture content of grains from plants bent 2 weeks before PM, at PM, and 2 weeks after PM, for example, were, at harvest, 23.3, 25.3, and 31.7 per cent, respectively, compared to 38.3 per cent recorded for unbent plants. Similarly, while only 1 - 2 plants/m2 lodged on plots with bent plants, an average of 5 plants/m2 lodged on plots with unbent plants. Cob infestation with stemborers/earworms, incidence of mouldiness, and grain damage per cob, also, were lower in bent than in unbent plants. Dry weight of marketable grains per cob was significantly highest (79.85 g/cob) in plants bent at PM and lowest (71.35 g/cob) in plants bent 2 weeks earlier. These results indicate that the bending over of maize plants has crop protection value. They further show that the ideal developmental stage to bend plants to combine the benefits of reduced pre-harvest grain moisture contents and field losses with maximum grain yield is at PM. Ghana Jnl.agric. Sci Vol.31(2), 1998: 169-17

Investigation into the seed-borne nature and seed to seedling transmission of Phytophthora in cocoa

The study verified a report that Phytophthora spp., causing black pod disease of cocoa in Ghana, are seed-borne and systemically transmitted to seedlings. To demonstrate seed borne nature, seeds from healthy and diseased cocoa pods were assayed for Phytophthora spp. Seed to seedling transmission was studied by artificially inoculating visually healthy seeds with P. palmivora, incubating the seeds in humidified Petri dishes, sowing in plastic cups and biopsying parts of the emerging seedlings for the fungus. Uninoculated seeds were sown as controls. Mature seedlings from a farmer's nursery and seedlings from seeds of naturally diseased pods were also assayed. All 1,028 seeds from healthy pods were free of Phytophthora. In contrast, 63% of seeds from diseased pods harboured the fungus. Detection of Phytophthora from the various components of infected seeds was highest for the mucilage/testa (57% detection frequency,) followed by the embryo (38%) and cotyledon (37%). Phytophthora palmivora was detected in rhizosphere soils, roots, stem bases, undetached cotyledons and testas of undetached cotyledons of seedlings from artificially infected seeds. It was absent from the middle and upper portions of stems as well as from leaves of such seedlings. Similar results were obtained with naturally infected seeds. The fungus was neither detected in farmer seedlings nor in seedlings of uninoculated seeds. It is concluded that systemic transmission of Phytophthora from the cocoa seed to the leaves of seedlings is impossible.Journal of Science and Technology(Ghana) Vol. 27 (1) 2007: pp. 9-1

Formulation of dehydrated media from the bean mucilage and placenta of mature unripe cocoa pods for culturing Phytophthora palmivora (Butl.) Butl.

No Abstract Available Ghana Jnl agric. Sci, Vol.36 2003: 97-10

Etiological and epidemiological studies on the red leaf disease of pineapple in Ghana

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 (