Ascospore dispersion of the causal agent of nectria blight of Piper nigrum.

Abstract

The ascospore production and dispersion of the causal agent of Nectria blight (=Mariquita disease or Fusarium disease) of black pepper (Piper nigrum) in the Amazon region of Brazil was studied. The anamorph of the pathogen belongs to a forma specialis of Fusarium solani. The teleomorph of the causal agent is easily produced when two individuals belonging to different mating types meet. Ascocarps which were considered to belong to Nectria were collected on dead or deteriorated pepper vines in the fields. Most of ascospores isolated from them could invade the pepper vine upon artificial inoculation. When the ascocarps were moistened, ascospores were easily dispersed by air flow. In field experiments they were detected as much as 170cm above and 300cm horizontally away from the source. Ascospore dispersion of the causal agent is considered to be an important factor in the spread of epidemics of the disease in the Amazon region, in addition to seedling transmission and fertilizer problems. We propose “Nectria blight” against “Mariquita disease” or “Fusarium disease” of black pepper vine as the most suitable name for this disease.