US interceptions of Tilletia indica from 1984 to 2000
Tilletia indica (EPPO A2 list) was discovered for the first time in USA in 1996 (EPPO RS 96/062). Studies were done to identify likely pathways of introduction of T. indica into USA by means other than natural air movement. The USDA-APHIS database of interceptions (USDA/APHIS Port Information Network) was analysed with data collected from 1984 to 2000. Over this period, 925 interceptions of T. indica were done. All interceptions were made on wheat from Mexico, and the fungus was not found on consignments from any other country. 98.8% of these interceptions were made at land border crossings in Texas and Arizona (a few were made at airports). 80 % of these interceptions were made from bags or loose grain found in cars, trucks or railway cars. Surprisingly, commercial cargo represented only 20 % of the interceptions. Over the period studied, a peak of interceptions was observed in 1986 and 1987; and within one year, interceptions were mostly made in May. These studies indicated the existence of pathways allowing repeated introductions of T. indica into USA.
Marshall, D.; Work, T.T.; Cavey, J.F. (2003) Invasion pathways of Karnal bunt of wheat into the United States. Plant Disease, 87(8), 999-1003.