July 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 has not yet been completed. 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 continues. From April 13th to July 30th, nine batches of samples of citrus leaf litter were routinely collected from orchard near Immokalee. Each batch of samples contains 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. These new data will be combined with the other data to analyze the seasonal dynamics of Phyllosticta spp. spores. In Australia, work continues on the mating and production of ascospores for Phyllosticta on leaf disks in culture. After 6 months they are still under observation. No inhibition is seen between isolates unlike on culture media. There is good growth of asexual structures. Inoculated fruit are still under observation in the field. Some accessions have started to mature and so far the results are as expected with sweet orange related fruit but many relatives have not reached maturity yet. They are repeating the fungicide work to confirm previous results.