Cross-Inoculation of Commercial Forestry, Amenity, and Horticulture Tree Species with Ceratocystis Isolates Collected from Different Host Species.

Ceratocystis manginecans has caused significant losses in forestry productivity in Indonesia and neighboring nations. It also infects horticultural trees, but the host range of individual isolates of C. manginecans is poorly studied. So, this study aimed to better understand the potential host range and evaluate aggressiveness against forestry and fruit tree species of C. manginecans isolated from various tree species in Indonesia. Five C. manginecans isolates, four from different tree species and one from the shot-hole borer Euwallacea perbrevis, were used to inoculate seven fruit and six forest tree species, including E. pellita and Acacia mangium. Many of the inoculated trees produced typical canker disease symptoms, such as rough, swollen, and cracked lesions on the bark, but some trees did not have any external symptoms. Mortality in the most susceptible clone of A. mangium was 40% within 8 weeks. Forest tree species were more susceptible than fruit trees, with the length of xylem discoloration ranging from 0.4 to 101 cm. In fruit trees, the average extent of xylem discoloration was lower, ranging from 0.4 to 20.5 cm; however, mortalities were recorded in two fruit tree species, Citrus microcarpa and Durio zibethinus. Host-isolate interaction was evident; isolate Ep106C from Eucalyptus pellita caused the greatest xylem discoloration in Citrus sp., whereas Hy163C from Hymenaea courbaril was the most damaging in D. zibethinus, Artocarpus heterophyllus, and Mangifera indica. Increasingly globalized food and fiber systems increase risk of disease spread, and the serious threat of C. manginecans incursions into countries where it is not present must be evaluated more thoroughly.

Near infrared spectroscopy for cost effective screening of foliar oil characteristics in a Melaleuca cajuputi breeding population.

The identification of Melaleuca cajuputi leaf samples (trees) that demonstrate enhanced oil characteristics using near infrared (NIR) spectroscopy is described. Leaf samples from an unthinned M. cajuputi seedling seed orchard in Indonesia were collected and air-dried, and their 1,8-cineole content and oil concentrations were determined. NIR spectra of the leaves were obtained, and calibrations for 1,8-cineole content and oil concentration were developed using spectra that had been selected using spectral features; that is, no knowledge of 1,8-cineole content or oil concentration was used to select the calibration samples. The calibrations were used to predict the 1,8-cineole content and oil concentration of the remaining samples. It was demonstrated that NIR spectroscopy could be used to identify leaf samples that had high 1,8-cineole contents and oil concentrations. The technique has the potential to greatly reduce the time involved in ranking large numbers of samples for these attributes, as is a requirement in tree breeding programs to enhance oil production.