In 1998, a new disease of Fortune mandarin trees was detected in orchards in the eastern province of Valencia. This is one of the most important late-maturing cultivars grown in Spain. Symptoms were typical of Alternaria brown spot of citrus (2). Young leaves showed brown necrotic and irregular blighted areas with characteristic yellow halos. The necrosis had a tendency to follow the veins. On fruits, symptoms included light brown, slightly depressed spots to circular and dark brown areas on the external surface. Infected young fruits and leaves often fell and the mature fruits were unmarketable due to lesions, resulting in important economic losses. Isolations on potato dextrose agar supplemented with 0.5 mg/ml of streptomycin sulfate (PDAS) from affected leaves and fruits consistently yielded Alternaria alternata (Fr.:Fr.) Keissl., which was identified based on conidial morphological characteristics. Pathogenicity tests were conducted using 15 isolates from fruit and leaves by inoculating detached immature Fortune leaves with a sterile water suspension of 5 × 105 conidia per ml. Drops of this suspension (40 μl each) were placed on the lower surfaces of each leaflet using four leaves per isolate. Leaves were incubated in a moist chamber in the dark at 27°C (1). After 48 h, most of these isolates caused necrotic lesions on the leaves similar to those observed in the field, and the fungus was reisolated, confirming Koch's postulates. In 1999, the fungus spread to other citrus-growing areas, and to date the disease has been detected affecting Fortune and Nova mandarins and Minneola tangelo. This is the first report of Alternaria brown spot of citrus in Spain. References: (1) K. Kohmoto et al. Phytopathology 81:719, 1991. (2) J. O. Whiteside. Plant Dis. Rep. 60:326, 1976.

The discipline of plant pathology has an expanding remit requiring a multi-faceted, interdisciplinary approach to capture the complexity of interactions for any given disease, disease complex or syndrome. This review discussed recent developments in plant pathology research and identifies some key issues that, we anticipate, must be faced to meet the food security and environmental challenges that will arise over coming decades. In meeting these issues, the challenge in turn is for the plant pathology community to respond by contributing to a wider forum for multidisciplinary research, recognising that impact will depend not just on advances in the plant pathology discipline alone, but on interactions more broadly with other agricultural and ecological sciences, and with the needs of national and global policies and regulation. A challenge more readily met once plant pathologists again gather physically at international meetings and return to the professional and social encounters that are fertile grounds for developing new ideas and forging collaborative approaches both within plant pathology and with other disciplines. In this review we emphasise, in particular: the multidisciplinary links between plant pathology and other disciplines; disease management, including precision agriculture, plant growth and development, and decision analysis and disease risk; the development and use of new and novel plant protection chemicals; new ways of exploiting host genetic diversity including host resistance deployment; a new perspective on biological control and microbial interactions; advances in surveillance and detection technologies; invasion of exotic and re-emerging plant pathogens; and the consequences of climate change affecting all aspects of agriculture, the environment, and their interactions. We draw conclusions in each of these areas, but in reaching forward over the next few decades, these inevitably lead to further research questions rather than solutions to the challenges we anticipate.

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A crown, root and fruit rot of squash (Cucurbita maxima and Cucurbita moschata) has been observed in eastem provinces of Spain over the past 4 years. Isolations from the crown of symptomatic plants and fruits yielded primarily a Fusarium solani that was identified as F. solani f. sp. cucurbitae race 1 on the basis of pathogenicity tests and disease symptoms in the field. In Spain, more than 90% of watermelon plants are grafted, using different Cucurbita hybrids (C. maxima x C. moschata) as rootstocks. In 1998, some grafted watermelon plants were first found to be affected by F. s. cucurbitae race 1. The purpose of this study was to evaluate the pathogenicity of this fungus on several rootstocks commonly used for grafting watermelon (Brava, Titan, Shintoza, RS-841, TZ-148 and TW-1) in order to prevent a possible spread of this fungus that could cause serious economic losses in watermelon production. None of them proved to be resistant.

O colapso em cucurbitáceas é uma síndrome complexa na qual podem estar envolvidos numerosos agentes fitopatógenos, sendo bastante freqüente o ataque associado de vários deles. No presente trabalho é apresentado o comportamento de 19 cultivares de meloeiro (Cucumis melo) e duas de melancia (Citrullus lanatus), cultivadas no Brasil, frente a Acremonium cucurbitacearum e Monosporascus cannonballus, dois dos patógenos fúngicos associados a esta síndrome em diversos países. Todas as cultivares de meloiro e melancia mostraram-se susceptíveis a estes patógenos, obtendo-se valores de 2,2 até 4,4 de índice geral de doença (IGD) para as cultivares de melão inoculadas com ambos os fungos e 2,4 até 2,5 para as cultivares de melancia inoculadas com A. cucurbitacearum. As cultivares de melancia mostraram resistência na combinação com M. cannonballus. A conveniência de efetuar estudos com outras cultivares utilizando a metodologia desenvolvida neste trabalho é discutida.