First Report of Crenate Broomrape (Orobanche crenata) on White Lupine (Lupinus albus) Growing in Alkaline Soils in Spain and Egypt.

Crenate broomrape (Orobanche crenata Forsk.) is a parasitic weed known to threaten legume crops since antiquity. It is mainly restricted to the Mediterranean Basin, Southern Europe, and the Middle East where it is an important pest in grain and forage legumes and in some apiaceous crops such as carrot and celery (1). White lupines are cultivated in acid soils, which usually are free of O. crenata infestations. However, breeders are attempting to develop white lupine cultivars adapted to alkaline soils (2). We report here findings of O. crenata infection in field trials of this new lupine germplasm in alkaline soils in experimental farms with a known history of faba bean cultivation and heavy infestation of O. crenata in Kafr El-Sheikh, Egypt and Córdoba, Spain in the spring of 2009. Symptoms were typical of O. crenata infection with reduced growth and emergence of typical O. crenata nonbranched spikes close to the lupine plants. Infection was confirmed by digging up the plants to verify the attachment of the broomrape plant to the lupine. O. crenata plants growing on lupines were fully fertile, producing viable seeds. Plant morphology was typical of O. crenata (1). Voucher specimens were deposited at the Herbarium of the Botanic Department of the University of Córdoba. To our knowledge, this is the first report of O. crenata infecting lupine and is relevant because the expected introduction of alkaline-tolerant lupine cultivars will extend its area of cultivation into fields heavily infested with Orobanche. O. crenata is highly polymorphic and could easily adapt to, recognize, and infect this new host. Development of lupine-adapted O. crenata populations should be monitored because it could represent a major constraint on lupine introduction into alkaline soils. References: (1) D. M. Joel et al. Biology and Management of Weedy Root Parasites. Page 267 in: Horticultural Reviews. Vol. 33. John Wiley and Sons, Inc. Hoboken, NJ, 2007. (2) M. Vishnyakova and A. Mikic, White lupin (Lupinus albus L.) landraces and the breeding for tolerance to alkaline soil reaction. Page 142 in: Second GL-TTP Workshop: Integrating Legume Science and Crop Breeding. Novi Sad, Serbia, 2008.

Infection Structures of Host-Specialized Isolates of Uromyces viciae-fabae and of Other Species of Uromyces Infecting Leguminous Crops.

A study was made of the morphology of urediniospores and primary infection structures of 12 isolates of six legume-infecting species of Uromyces. Infection structures were sufficient to distinguish among species. Isolates of Uromyces viciae-fabae proved to be specialized with respect to host, because each isolate infected only cultivars of the species from which it was collected. Host-specialized isolates of U. viciae-fabae also were morphologically distinct, differing in both spore dimensions and infection structure morphology. In particular, the shape and dimensions of the substomatal vesicle were distinctive. These results support the view that U. viciae-fabae sensu lato is a species complex.