Non-PR | IFPRI4

The major banana pests and diseases influenced by poor field management are highlighted. Control of leaf spot (Sigatoka) benefits from a plant density from 1550 to 2100 mats/ha, weed control and detrashing and adequate surface drainage. Nematodes, borers (cosmopolites sordidus), thrips and mosaic virus are reduced by weed control, trash removal and sleeving

Outlines the history and objectives of the California Citrus Clonal Protection Program (CCPP) which conducts research and is a primary source of disease-free budwood of desirable true-to-type citrus scion and rootstock varieties designed to exclude graft transmissible diseases (virus and virus-like)

Research is directed towards study of host-parasite relations. The 3 Sigatoka leaf spot pathogens, Mycosphaerella musicola (Yellow Sigatoka), M. fijiensis (Black Leaf Streak) and M. fijiensis difformis are compared morphologically and pathogenically. Species identification by electrophoresis on acrylamide gels has been studied, the species also differ in host range, geographical range, symptoms and distribution of lesions. Early tests of susceptibility of plantlets from meristem culture suggest that they react to infection in the same way as observed in the field

The leaf spot diseases of bananas and plantains, Sigatoka and Black Sigatoka, caused by Mycosphaerella musicola and M. fijiensis var. difformis are distributed worldwide and only in Central America respectively. Epidemiological studies are described in detail including seventy of the pathogens at different sites and correlation with climatic data. Susceptibilities of different banana and plantain genomic groups were found to be nearly identical for both diseases except that Black Sigatoka is more virulent so that both pathogens occupy the same ecological niche. A method developed to test the susceptibility of musa clones to Black Sigatoka using plantlets derived from shoot tip culture is described

Of the citrus diseases occurring in Surinam, fungal, bacterial, viral and those caused by nematodes, tristeza is most important. Trials to identify the best rootstocks to replace the tristeza-susceptible sour orange found Rangpur lime budded with nucellar Alidjan orange best on heavy clay soils. Sunki and King (tangors) are good rootstocks for grapefruit varieties. Research showed tristeza virus transmission by the aphid vector Toxoptera citricidus to be bi-modal (non-persistent and semi-persistent) in Surinam, with the latter more common

Phytosanitary practices are recommended to reduce the incidence in the Windward Islands of banana pests and diseases: leaf spot (Mycosphaerella musicola), crown rot (Fusarium roseum), virus diseases (bunchy top), moko disease (Pseudomonas solanacearum), banana borer (Cosmopolites sordidus), rust thrips (Chaetonophothrips signipennis), flower thrips (Frankliniella parvula), Lachnopus beetle and nematodes

Describes a purification method for the Bunchy top virus based on density gradient centrifugation which allowed observation of the virus particles for the first time. Thirty micrograms of virus were obtained from 200g of infected leaves. To obtain large amounts of virus for antisera preparation the purification procedure has to be improved