Pitch canker is a highly damaging disease of Pinus radiata and the New Zealand forest industry is concerned by the potential impact of the disease, should it arrive, in New Zealand. To provide a rapid identification technique for this pathogen, a polymerase chain reaction-based diagnostic method has been developed. The method is able to detect the presence of the pathogen within infected host tissue, as well as infested soil and the reliability of the test has been estimated using Bayesian statistics.
Myrtle rust, caused by the fungus Austropuccinia psidii, is a serious disease, that affects many Myrtaceae species. Commercial nurseries that propagate Myrtaceae spp. are prone to myrtle rust and require a reliable method that allows pre-visual and early detection of the disease. This study uses time-series thermal imagery and visible-to-short-infrared spectroscopy measurements acquired over 10 days from 81 rose apple plants (Syzygium jambos (L.) Alston) that were either inoculated with myrtle rust or maintained disease free. Using these data the objectives were to (i) quantify the accuracy of models using thermal indices and narrowband hyperspectral indices (NBHI) for pre-visual and early detection of myrtle rust using data from older resistant green leaves and young susceptible red leaves and (ii) identify the most important NBHI and thermal indices for disease detection. Using predictions made on a validation dataset, models using indices derived from thermal imagery were able to perfectly (F1 score = 1.0; accuracy = 100%) pre-visually distinguish control from infected plants one day before symptoms appeared (1 DBS) and for all stages after early symptoms appeared. Compared with control plants, plants with myrtle rust had lower and more variable normalised canopy temperature, which was associated with higher stomatal conductance and transpiration. Using NBHI derived from green leaves, excellent pre-visual classification was achieved 3 DBS, 2 DBS and 1 DBS (F1 score range = 0.89 to 0.94). The accurate characterisation of MR during pre-visual and early stages suggests that a robust detection methodology could be developed within a nursery setting.
Mvcosphaerella suberosa is repofled for the ''st time from New Zea1and On Eucalyptus muelleriana. It has slightly smaller pseudothecia than those described for M. suberosa fi-om Brazil and Australia and is from a previously unrecorded host. Mycosphaerella intemedia sp. nov. on Eucalyptzds saligna is also described. An annotated list of the six Previously recorded species Of Mycosphaerella On Eucalyptus in New Zealand is included.
The common diseases of pines caused by Fusarium species in New Zealand are dampingoff and root rot disorders of seedlings in forest nurseries The emergence of pine pitch canker disease caused by Fusarium subglutinans f sp pini as a serious threat to Pinus radiata plantations has increased the need for an awareness of the species associated with pines in New Zealand Standard morphological procedures were used to identify Fusarium cultures isolated from diseased pines and from soil in forest nurseries Fusarium oxysporum and F solani were the most commonly found species in bareroot P radiata nurseries and were obtained from both seedlings and from soil The species most frequently obtained from branches and needles of older trees in plantations were F avenaceum and F sambucinum but these were not associated with serious disease
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