Transmission of Bipolaris sorokiniana from seeds to wheat coleoptile.
Seeds of the cv. Anahuac with 16-90.5% natural infection by B. sorokiniana (Cochliobolus sativus) and treated or not with iprodione + thiram (50 + 150 g/100 kg seeds) were sown in sand in the greenhouse or in soil in the field. The transmission index was variable, higher values corresponding to higher seed contamination and/or infection indices. The correlation between incidence on the seeds and transmission to seedling coleoptiles was positive and significant, both in the field (r=0.985**) and greenhouse (r=0.923**). With untreated seeds, the av. transmission was 66% (transmission index 1.54:1) and with treated seeds 32% (1.92:1). A transmission index of 1.1:1 was determined for a seed sample with 90.5% natural infection. At a sowing density of 400 viable seeds/m2 this could mean the establishment of 3 290 909 infection foci/ha.