Collection of meaningful data on long distance dispersal (LDD) of plant pathogens is very difficult because such events are very rare and the strength and locations of pathogen sources are often unknown This review of the different methods that have been deployed examines combinations of meteorological analyses and ground surveys including spore trapping devices collecting rainwater and identifying spores using realtime PCR The relevance of these techniques is discussed in the context of surveillance and monitoring transTasman dispersal of fungal spores

The long distance dispersal of many plant pathogens has been well documented.

The wheat cultivar Consort was artificially inoculated with Septoria tritici in an experiment to determine the latent period of the pathogen in New Zealand Three individual leaf layers (leaf three leaf two or the flag leaf) were inoculated over three sowing dates to provide a range of different environmental conditions following inoculation The mean latent period was 21 to 27 days (291372C days) The length of the latent period increased slightly with delays in sowing date The implications for producing a simple forecasting system to assist farmers with timing of fungicide applications are discussed

A field trial was carried out to determine the length of latent periods of Septoria tritici blotch on 10 cultivars of wheat After artificial inoculation of the flag leaves of all cultivars on a single date lesions of S tritici showing pycnidia were produced over intervals of 21 to 37 days (273 to 459C days) after inoculation Latent periods varied between the cultivars tested with cv Domino having the shortest and cv Regency the longest latent periods The period of symptom expression for the different cultivars varied from 0 to 11 days (0 to 122C days) with a mean of 50 (544C days) This research provides information that can be used to develop disease models and forecast systems to assist growers with disease control decisions

A spring-sown field trial at Lincoln in the 2001/2002 growing season assessed the relative protectant and eradicant activity of the fungicides azoxystrobin and epoxiconazole, for control of wheat stripe rust caused by the fungus Puccinia striiformis. The fungicides were applied at different stages of a stripe rust epidemic, nil disease, trace of disease or moderate disease, on five wheat cultivars which differed in susceptibility to the disease. Disease severity and host reaction were also measured. The mean area under the disease progress curve (AUPDC) of flag leaves of the susceptible cultivar Tiritea was reduced by 65% after application of azoxystrobin, and by 37% after application of epoxiconazole. The AUDPC for the moderately susceptible cultivar Karamu was reduced by 41-50% by both of the fungicides. The more resistant cultivars, Impact, Sapphire and Otane, had very low AUDPCs and would probably not benefit from an application of fungicide to control stripe rust, unless the pathotype present was highly virulent against these cultivars. Depending on disease pressure, fungicides on susceptible cultivars should be applied at or near flag leaf emergence.