Dry flower disease of Macadamia in Australia caused by Neopestalotiopsis macadamiae sp. nov. and Pestalotiopsis macadamiae sp. nov

Incidence of dry flower disease of macadamia (Macadamia integrifolia), expressed as blight of the flowers, necrosis and dieback of the rachis, is increasing in Australia. In the 2012/13 production season, incidence of dry flower disease resulted in 10% to 30% yield loss in the affected orchards. Etiology of the disease has not been established. This study was established to characterise the disease and identify the causal pathogen. A survey of the major macadamia producing regions in Australia revealed dry flower disease symptoms, regardless of cultivar or location at all stages of raceme development. Based on colony and conidial morphology, the majority (41%) of fungal isolates obtained from tissue samples were identified as Pestalotiopsis and Neopestalotiopsis spp. The phylogeny of the combined partial sequence of the internal transcribed spacer, beta-tubulin and translation elongation factor 1-alpha gene loci, segregated the isolates into two well supported clades, independent of location or part of the inflorescence affected. Further morphological examination supported the establishment of two new species, which are formally described as Neopestalotiopsis macadamiae sp. nov. and Pestalotiopsis macadamiae sp. nov. Using spore suspensions of isolates of both species, Koch?s postulates were fulfilled on three macadamia cultivars at all stages of raceme development. To our knowledge, this is the first report of species of Neopestalotiopsis and Pestalotiopsis as causal agents of inflorescence disease in macadamia.

Does fumigation of durum wheat and semolina with sulfuryl fluoride affect quality of the grain, semolina, and derived spaghetti and bread?

There is no information on the effect of sulfuryl fluoride (SF) on durum wheat technological properties and products made from fumigated durum wheat. Durum wheat and semolina were exposed to a range of SF applications under conditions that might be typically encountered in bulk storage facilities used in many countries. SF greatly reduced the germination percentage of fumigated durum wheat, with increasing impact under higher SF concentration, grain moisture content, and fumigation temperature. SF greatly reduced seed germination percentage, impacting more the higher the SF concentration. SF had little to no effect on grain test weight, 1,000-grain weight, hardness, protein content, semolina ash content, and mixograph properties. At the highest SF concentration (31.25 mg/L for 48 h) there was a tendency for pasta cooking loss to be increased but still acceptable, and other pasta properties were largely unaffected. Fumigation with SF did not have any impact on the baking properties of a wholemeal durum flour-commercial flour mix. Therefore, SF is not recommended if the grains are to be used as seeds for agricultural production, but for the production of semolina, pasta, and bread, SF used under typical fumigation conditions has little to no impact on technological properties of durum wheat. © 2016 AACC International, Inc.