Disease Note

Alternaria Leaf Spot, a Previously Unreported Disease of Acalypha indica in the Seychelles Islands. G. C. Kingsland, Department of Plant Pathology and Physiology, Clemson University, Clemson, SC 29631. Plant Dis. 68:1016. Accepted for publication 3 October 1984. Copyright 1984 The American Phytopathological Society. DOI: 10.1094/PD-68-1016e.

Acalypha indica L. (Euphorbiaceae) is an indeterminate annual weed of East Africa and circum-Indian Ocean distribution. A previously unreported leaf-lesion disease caused by an Alternaria sp. with apical cells equal to or longer than the conidial body was discovered on this host in the Republic of Seychelles. Mature lesions were circular with gray, necrotic centers measuring 0.5 mm, encircled by 0.4 mm wide black borders. A 0.4 mm wide chlorotic halo enclosed each lesion. Lesions were not restricted by veins and extended through the leaf. Conidia of this Alternaria sp. developed on 85% of the lesions observed from various locations on Mahi. Island. Mycelial fragments and conidia transferred to healthy leaves of A. indica resulted in symptoms on 40 and 66%. respectively, of the loci inoculated. The Alrernaria sp. was reisolated from representative lesions. Comparisons with other reported Alternaria spp. on Acalypha spp. suggested that this species is similar to A. recini but distinct from it based on conidial morphology and host range.