September 2015 The objectives of this proposal are 1) to determine if a) leaf litter biodegradation treatments reduce Guignardia spp. pseudothecia and improve control afforded by routine fungicide applications; b) if biodegradation is affected by the current fungicide application practices; and c) whether the biodegradation treatments will affect current citrus best management practices (BMP); 2) to determine the seasonal dynamics of leaf litter inoculum load in varying management regime intensities and how environment affects pseudothecia production in the leaf litter; 3) to test if the resistance to black spot in the leaves and fruit in sour orange is correlated and under simple genetic control through laboratory and field testing of progeny of sour orange crosses in both Florida and Australia. In the large field trial, there was ten times more G. mangiferae than G. citricarpa in the leaf litter. In 2014, there was no pattern in the number of leaves with Guignardia structures over time in any treatment. The treatment with the greatest number of leaves with structures was urea over all. In 2015, the pattern of structure formation was consistent across treatments and over all the treatment with the fewest structures was urea. The DNA analysis of the 2015 leaf litter is continuing. The extractions are complete but the PCR is not complete The bagasse field trials confirmed the laboratory experiments that bagasse increased the leaf decomposition rate compared to nothing or urea. Greater soil moisture also accelerate leaf decomposition. The manuscript preparation is still not complete. Collection of leaf samples from the grove in Immokalee has continued biweekly. Each batch of samples contained 40 samples of 25 leaves collected below 40 trees. Leaves were examined under microscope to check for fructification of Phyllosticta spp. Leaf portions without fructification were discarded and the remainder were immersed in 0.02% tween20 to collect conidia and ascospores. Conidia and ascospores produced in leaf litter were quantified, weather data were collected from FAWN. Data collection continues and we are trouble shooting the qPCR to make sure that it is working properly before samples are processed. In Australia, work continues on the mating and production of ascospores for Phyllostictam citricarpa in culture. None were formed on the leaf discs but pseudothecia were formed using another technique. Confirmation of the results is under way. Inoculations of fruit are underway in the field. They are repeating the fungicide work to confirm previous results. They are also continuing to sample leaf litter in two groves in Queensland mandarin growing region.