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The rapid emergence of Acacia mangium as the key industrial plantation species in Indonesia has been followed by the equally rapid emergence of red root rot (Ganoderma philippii) as its potential nemesis. As a consequence, and on severely affected mineral soils in equatorial tropical environments in particular, A. mangium may no longer be capable of producing commercial yields after three rotations. In this experiment, 100-tree plots were established in commercial plantings of A. mangium at five sites which represented the range of growing conditions used for plantation establishment in Indonesia. Repeated monitoring at approximately 6-month intervals of above-and below-ground variables was used to explore relationships between measures of tree health and root rot. Crown colour and density were poor predictors of either the presence or severity of infections. Tree mortality increased more or less linearly with time and led to the progressive coalescence of initially discrete disease gaps. The average rate of disease development was about 0.3% per month, and average time from infection to tree death was conservatively estimated at around 1 year. Trees with more than four dead/missing neighbours had a >50% chance of being dead by the following monitoring. By the end of the monitoring period >40% of trees were classified as dead/missing, although this value varied from 20 to 70% depending on site, tree age and rotation. Canonical discriminant analysis correctly allocated >90% trees into their correct group on the first monitoring and similarly classified whether trees would be dead or missing in the following monitoring.

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The genus Ceratocystis includes many important tree pathogens and agents of sap stain. These fungi have a global distribution and commonly infect wounds on trees. During a survey of woundinfecting pathogens in the genus Ceratocystis on plantation-grown Acacia mangium trees in Indonesia, several isolates resembling Ceratocystis moniliformis sensu lato (s.l.) were obtained. The aim of this study was to identify these isolates and to test their pathogenicity on commercially grown Acacia spp. in the country. Use was made of morphology and comparisons of DNA sequence data for the ITS, β-tubulin, and transcription elongation factor 1-α gene regions to identify the isolates. Three previously undescribed species in the C. moniliformis s.l. species complex were identified and are described here as C. inquinans sp. nov., C. sumatrana sp. nov., and C. microbasis sp. nov. Pathogenicity trials on Acacia mangium and A. crassicarpa in the greenhouse and in the field indicated that all three species have the potential to infect A. mangium and A. crassicarpa, although they are not considered important pathogens.

Xanthomonas campestris pv. glycines is the causal agent of bacterial pustule disease of soybeans. The objective of this work was to construct a nonpathogenic mutant derived from the pathogenic wild-type strain YR32 and to evaluate its effectiveness in preventing growth of its parent on the soybean phyllosphere. A mini-Tn5-derived transposon was used to generate nonpathogenic mutants. Southern hybridization and pulsed-field gel electrophoresis confirmed the presence of a single transposon in each of the nonpathogenic mutants. One of the nonpathogenic mutants, M715, failed to induce a hypersensitive response in tomato leaves. An ice nucleation gene (inaZ) carried in pJL1703 was introduced into strain YR32 as a reporter gene to demonstrate that the presence of M715 could reduce colonization of the soybean phyllosphere by YR32. de Wit serial replacement analysis showed that M715 competed equally with its wild-type parental strain, YR32. Epiphytic fitness analysis of YR32 in the greenhouse indicated that the population dynamics of strains YR32, YR32(pJL1703), and M715 were similar, although the density of the mutant was slightly less than that of its parent. The M715 mutant was able to survive for 16 days after inoculation on soybean leaves and maintained population densities of approximately 10 4 to 10 5 cells g (fresh weight) of leaf ؊1 . Therefore, M715 shows promise as an effective biocontrol agent for bacterial pustule disease in soybeans.