In an experiment examining the relationship between seed-borne net
blotch infection levels (nil – 40%), the presence or absence of infected stubble and the application of seed treatment it was found that disease symptoms at growth stages (GS) 20/21 and 31 are directly correlated to levels of seed infection. Seed treatment effectively controls the disease at GS 20/21 and GS31, where seedborne infection is the only source of inoculum. At GS 31, where infected stubble was present, the application of seed treatment showed no benefit when applied to seed with infection levels of 15% or less. Flag leaf infection at growth stage 83 is unrelated to seed-borne infection and is due to a combination of different factors
which makes it difficult to deduce the significance of seed-borne inoculum in comparison to stubble inoculum. Where it is possible to develop strategies of treatment according to need for barley leaf stripe and loose smut, there is a need for further work in defining meaningful seed infection thresholds for net blotch. There is also a need to educate seed producers and growers regarding the management of seed-borne disease in the production of healthy seed crops.