Occurrence of algal stem blotch in ber (Ziziphus mauritiana) under coastal Odisha conditions in India

Abstract

The investigation was carried out during 2017-18 to identify and document the emerging diseases of Indian Jujube or ber (Ziziphus mauritiana Lamk.) in Odisha state located in Eastern part of India. Periodical visit and subsequent investigations revealed the occurrence of a new kind of stem blotch disease in ber caused by alga. Symptoms were observed on bark of the stem and branches as bright red velvety blotch colonies during July- September 2017. However dull grey blotches were visible throughout the year. Leaves and fruits were left unaffected. The algal stem blotch occurrence was assessed during the year 2018 and disease severity rangedfrom 9.4-14.8 per cent. The green alga was identified and confirmed as Trentepohlia arborum (Agardh) Hariot based on key morphological characters. The stem blotches lead to death of young twigs measured between 3 to 8 mm thickness on primary and secondary branches wherein thickness of branches was more than 10 mm, algal blotches caused cracking of bark. Present study highlights the causal agent of stem blotch of ber, its symptomatology, impact of disease and suggested management practices.