BLACKPOINT INCIDENCE ON DURUM WHEAT IN ARGENTINA: INFLUENCE OF CULTIVAR AND LOCATION

Blackpoint is characterised by a brown to black discoloration of wheat kernels and occurs in all the major wheat growing regions of the world. This disease is caused primarily by either Alternaria alternata or Bipolaris sorokiniana. Subproducts from diseased durum grains contain undesirable black specks that cause downgrading on the quality. From trials in 5 locations of southern Buenos Aires Province, samples of wheat grains were analysed to determine the effect of cultivar and location on the natural incidence of blackpoint and to identify the organisms associated with the disease. Incidence (% of discoloured grains) was recorded on samples of 200 kernels per treatment and seed health testing was carried out using the "blotter test" method. A. alternata was found in most of the samples analysed, followed by B. sorokiniana, the latter showing very low infection levels. Other organisms were also found. Disease incidence differed between years and locations and none of the cultivars was completely free of the disease. These results showed that incidence levels were more closely correlated with favourable weather conditions than with certain characteristics of each cultivar.