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Title: KARNAL BUNT OF WHEAT NEWLY REPORTED FROM THE AFRICAN CONTINENT

Author
item CROUS, P - UNIV. OF STELLENBOSCH
item VAN JAARSVELD, A - SOUTH AFRICA
item Castlebury, Lisa
item CARRIS, L - WASHINGTON STATE UNIV.
item PRETORIUS, Z - UNIV. OF THE FREE STATE

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/13/2001
Publication Date: N/A
Citation: N/A

Interpretive Summary: Karnal bunt is a disease of wheat for which many countries have a strict quarantine because the fungus that causes this disease is known from only a few places around the world. Karnal bunt can seriously limit the ability to export wheat from a country in which Karnal bunt exists. This paper reports the discovery of Karnal bunt on wheat in South Africa. Bunted kernels were found from wheat grown in a limited area in the Northern Cape Province. A USDA bunt expert identified this fungus based on teliospore morphology including germination characteristics. This research will be important in evaluating quarantine regulations in regard to Karnal bunt of wheat.

Technical Abstract: In December 2000 seed harvested from the wheat (Triticum aestivum L.) cultivars cultivated under irrigation near Douglas, Northern Cape Province, South Africa, contained a high percentage of partially bunted seed. Kernel embryos contained black masses of teliospores and in many instances the endosperm was partially degraded. Teliospores were brown to dark brown, densely echinulate, 25-45 m in diam. with a short mycelial fragment on some of the spores. Germinating teliospores produced a large number of primary and secondary sporidia. Based on kernel appearance, a rotten fish odor in infected grain, teliospore morphology and germination, the disease was identified as Karnal bunt (Tilletia indica Mitra) (1). This identification was confirmed at the USDA-ARS Systematic Botany and Mycology Laboratory, Beltsville, MD, USA. Reference specimens were deposited at the National Fungal Collection in Pretoria, South Africa (PREM), and at Beltsville, USA (BPI). At present the mode of introduction of T. indica into South Africa, as well as its precise distribution, is not known. It appears, however, that the pathogen is restricted to the Douglas production area in the Northern Cape where quarantine measures have been taken to contain and possibly eradicate the disease. Tilletia indica is currently subject to quarantine by a number of countries including the U. S. and Australia.