January 2023 1. Please state project objectives and what work was done this quarter to address them:The objectives are to 2) determine if the flush cycle and infection period for Z. citri-griseum have changed due to the influence of HLB on citrus physiology or changing environmental factors; 4) evaluate the potential promotion of greasy-green symptoms related to nutrition programs or to peel reactions like a chemical burn from different pesticide and combinations of pesticide tank mixes; and 5) evaluate if postharvest degreening treatments might be modified to adequately remove the green coloration while mitigating poor shelf life from anticipated longer degreening times. Most of the progress to date have been on objective 2. Two sites were established in grapefruit groves in the Indian River region. These sites were identified to have significant problems with the greasy green disorder affecting the grapefruit industry. In each block, twenty trees were selected for uniform canopy without excessive thinning or obvious sectoring from HLB and mapped, and ten flushes per tree were tagged to be observed for greasy spot symptoms later in the season. Every two weeks from the beginning of May, ten leaves and one fruit per tree are collected. The fruit diameter has also been collected since June. The leaves are cleared and 5mm disk samples are examined under the microscope to observe whether there is epiphytic growth. Our previous method of sampling fruit was not giving satisfactory results so we have moved to applying clear nail polish to the fruit surface to remove the fungal growth and observing it under the microscope instead. We had much better success with the nail polish technique. We are also molecularly confirming that the structures we were observing under the microscope were Zasmidium citri-griseum. We have done a conventional PCR, observed bands at the correct size and preparing the samples for sequencing. The microscopy samples are preserved, and we are using the winter season to collect the observations for analysis. We presented some preliminary phenology data at the Southeastern Professional Fruit Workers Conference held in Lake Alfred in November. From our first observations in May to October2022, the majority of flush was fully mature with significant peaks of younger flush in June and September. The red and white grapefruit had similar patterns of flush but the red grapefruit had a longer flush period in the fall than the white. Fruit growth increased in a typical exponential pattern until September when the growth rate was substantially reduced as expected. The average diameter in October was 8 cm. The fruit are currently asymptomatic and spores and mycelial growth were observed from August. We are not sure if we did not detect them earlier in the season was because they were not there or an artifact of the way we were attempting to visualize them. We will hopefully determine the extent of epiphytic growth and when the epiphytic growth is the most prevalent to compare with what is known from previous work. Ideally, this will allow us to adjust when applications occur to better control greasy spot as part of the greasy green disorder. 2. Please state what work is anticipated for next quarter: Samples will continue to be evaluated microscopically. We plan to start evaulating flush in the early spring, probably mid-February or early March. Samples will continue to be collected. More fruit samples have been promised for the greasy-green physiology experiments and it is expected that several experiments following up on the ones already undertaken will be conducted. 3. Please state budget status (underspend or overspend, and why): No over or underspend on budget currently