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Pacific Pests, Pathogens & Weeds - Mini Fact Sheet Edition

Taro (Leptosphaerulina) leaf spot (318)

Photo 1. Leaf spots on taro, white, some merging, others falling out, caused by Leptosphaerulina trifolii.

Photo 2. Leaf spots on taro, caused by Leptosphaerulina trifolii.

Photo 3. Leaf spots on taro, on the underside of the leaf, caused by Leptosphaerulina trifolii.

Summary

Worldwide distribution. On taro, legumes, and many other vegetables, and weeds. A fungal disease of minor importance.
Associated with leaf spots or dead areas on a number of hosts, e.g., leaf spots on pepper (capsicum), a target spot on beans, leaf spots and corm rots on taro. On alfalfa, tan leaf spots are surrounded by brown margins, giving an "eyespot", sometimes with a yellow halo.
Spread in rain and wind, and possibily seedborne.
Cultural control: generally no recommendation; however, on alfalfa in the USA, lepto leaf spot is managed by early harvests; avoiding leaving cut plants in the field; crop rotations avoiding forage legumes for 2 years; and resistant varieties.
Chemical control: none recommended.

Common Name

Taro (Leptosphaerulina) leaf spot. CABI gives the preferred common name as soyabean leaf spot. In the USA, it causes alfalfa lepto leaf spot. Alfalfa is a forage legume.

Scientific Name

Leptosphaerulina trifolii. Previously known as Sphaerulina trifolii and Leptosphaerulina briosiana.

AUTHORS Grahame Jackson & Eric McKenzie
Photo 1 Fred Brooks, University of Hawaii at Manoa, Bugwood.org. Photos 2&3 (taken by Eric McKenzie), and used in this fact sheet, appeared previously in McKenzie E (2013) Leptosphaerulina trifolii. PaDIL - (https://www.padil.gov.au).

Produced with support from the Australian Centre for International Agricultural Research under project PC/2010/090: Strengthening integrated crop management research in the Pacific Islands in support of sustainable intensification of high-value crop production, implemented by the University of Queensland and the Secretariat of the Pacific Community.

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