 This meeting is being recorded. Good morning to everyone. It's my pleasure to present a part of my PhD research at today's APPS seminar series, the title of today's my presentation sources and quantification of flower blight pathogens in macadamia. I'm glad that a manuscript on this topic has been professionally accepted in the APS quite a pathology journal. Let's start with the introduction part macadamia tree net crop was originated from the eastern Australia. There are four species in the genus macadamia among them two species macadamia indigrefolia and macadamia tetrapyla and they are hybrids produced edible kernel. Macadamia kernels can be used to can be eaten as raw or roasted and can be used in the manufacture of oil or confectionaries. According to 2020 production statistics, the global production of macadamia was around 62,000 tons kernels where Australia contributed to one fourth of the global productions. In Australia, you can see in the map, the Vanderbilt region and Sunshine Coast regions in Queensland and also the northern rivers regions in New South Wales are the major macadamia production area. In Australia, the Russian elongations begins in mid to late winter that is June to July and the peak and this is occurs in late winter or early spring that is September. So the flower diseases of macadamia generally called as flower blight disease threatened the Australia macadamia industry. The poor flower retention and loss of fruit set due to flower diseases have been reported from all the macadamia production regions in Australia. The various for fungal pathogens affect macadamia racins in Australia, three types of flower blights have been reported. What right is blight also known as grey malt cladosporium blight or green malt and pestilate chirpsis blight or the dry flower disease. So we found that the dry flower disease is caused by multiple species of pestilates fungi including the two already known pathogens and one new host record and five novel pathogens. So the five novel species of the new pestilates chirpsis were named using the names of researchers working on macadamia plant protections. So all the novel species of the new pestilates chirpsis have been characterized and published in the journal of fungi last year. The several species of cladosporium including one non-pathogen and two host new records and three novel pathogens cause grey malt disease of macadamia. And the grey malt is caused by the already known pathogen what right is scenario and in addition to that what right is scenario we found that what right is macadamia the novel pathogen also causes the grey malt. So all the novel species of cladosporium and what right is have been characterized and published in another article in journal of fungi. So the knowledge of key components of disease cycles is very important for the disease cycle 1x for example the sources of inoculum the knowledge of the source of inoculum is very important for the effective management of flower blight disease. So it was hypothesized that the remnant racins from previous flowering seasons that persist in macadamia tree canopy could serve as the primary source of inoculum for all the three types of flower blights. We have identified and characterized a new disease called yellow-hellow-leaf sports which was published last year in the European journal of plant pathology. So this disease is caused by neo pestilates vene. So since this pathogen is also a causative agent of dry flower disease we suggested that the quantity are produced from the yellow-hellow-leaf sports could contribute to the dry flower disease. So based on this background this research was aimed to determine whether the remnant racins and yellow-hellow-leaf sports in the macadamia are the sources of flower blights and also to detect and quantify the relative amount of inoculum of the pathogens from the putative sources of inoculum using a QPCR assay. So the fungal isolates were obtained from the remnant racins and leaves with the yellow-hellow-leaf sports that were collected from the commercial macadamia orchards. Here you can see that the fungal genera, neo pestilates, cladosporium and botrytis were more frequently isolated from the remnant racins while the genus neo pestilates is the dominant genus isolated from the yellow-hellow-leaf sport. Pathogenicity trials were conducted on in two locations on two macadamia cultivars over the two flowering seasons using three types of materials. The first one, quantity of suspensions from the bio-cultures of the fungal isolates obtained from the remnant racins and leaves sports. The second one, quantity of suspension from the plant materials that is remnant racins and leaves sports and finally the incubation of healthy racins with the plant materials. So the inoculated racins were examined for flower blight symptoms and the disease severity was rated 14 days after the inoculation. The results of pathogenicity trials with bio-cultures showed the pre-presentative isolates of botrytis, cladosporium, neo pestilates and pestilates that were obtained from remnant racins produced the flower blight symptoms and also recorded the maximum disease severity on developing macadamia racins. Whereas the representative isolates of neo pestilates obtained from yellow-hellow leaves sports showed severe disease on macadamia racins. This figure shows the results of pathogenicity trials with plant tissues and quantity of suspension. Here you can see that the two treatments, quantity of inoculations and the direct tissue incubations from remnant racins produced significantly the highest disease severity. Whereas the two types of treatments involved with yellow-hellow leaves sports produced comparatively the lower disease severity in comparison to the treatments of remnant racins. Let's move on to the inoculum quantifications. So the quantity in remnant racins and leaves sports were quantified by a QPCR assay. For this, a multiplex QPCR was developed using already published primer pairs for botrytis and cladosporium. But for the pestilates and neo pestilates, we designed a new primer set and developed a QPCR assay which was published last year in the journal Plant Pathology. So the newly developed multiplex QPCR assay in the study had a higher amplification efficiency that is more than 93 percentage. And this assay was able to detect as few as 5 quantity per microliter of all the three types of flower blight pathogens. So the results of detection and quantification of inoculum from the remnant racins, the relative amount of cornedia of pestilates and neo pestilates was significantly the highest among the three types of flower blight pathogens. And also we noticed that the group pestilates and neo pestilates was directed by the QPCR assay from all the remnant racins samples that we collected and we included in this present study. From the yellow-hellow leaf spots, only the pestilates and neo pestilates quantity are detected that ranged from 100 to 1000 quantity per centimeter square, no any botrytis or cladosporium quantity are detected by the QPCR from yellow-hellow leaf spots. So based on the findings it can be concluded that the remnant racins are the potential source of inoculum for all the three types of flower blights in macadamia and also the yellow-hellow leaf spots only contribute to dry flower disease. So this suggests racins from the previous flowering season should be removed from the tree canopy as a control option of flower blights in macadamia orchards. Also, the inoculum density that can be estimated by the QPCR assay could be used for the disease development, disease prediction tool development. I would like to acknowledge my PhD advices associate professor Femi Akinthani and professor Vigalia and also the UQ Research Training Scholarship for my studies and also this project was funded by the Hort Innovation Macadamia Fund and the macadamia crovers in Queensland and New South Wales who permitted us to collect the samples from their orchards. Thank you very much.