A citrus rehabilitation programme is underway to restore abandoned estates through weed control, epiphyte and parasitic phanerogam removal, pruning, fertilization and improved drainage. Phytosanitary methods of control of Moko disease (Pseudomonas solanacearum race 2) and Yellow Sigatoka (Mycosphaerella musicola) of bananas are listed. Virus indexing of citrus cultivars has been initiated and research into tissue culture of banana plants started

The strategy is preventative based on a climatic forecasting system which receives data from 14 agroclimatic stations, complemented by biological assessments. The method used is termed 'state of evolution', an expression of the speed of disease development which varies with inoculum potential and climatic conditions. Benzimidazole and sterol-inhibiting fungicides are applied in rotation

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