Investigation of disease occurrences and rapid diagnosis in grafted cactus

Abstract

Grafted cacti constitute an important part of South Korea’s export floricultural industry. Korean grafted cacti occupy more than 70% of the world’s grafted cactus market. Many diseases (head rot, stem rot, basal rot) affect different species/cultivars of cacti, including Bimoran (Gymnocalycium mihanovichii var. friedrichii), So-Jung (Notocactus scopa) and San-Chwi (Chamaecereus silvestrii). This study was conducted to investigate the occurrence of diseases and their symptoms, accompanied by a molecular diagnosis of two major exported cactus cultivars, specifically So-Jung and Bimoran. Two commercial fields, greenhouse A (GA) and greenhouse B (GB), were investigated for the existence of pathogens, incidents of disease and their severity. GA indicated more disease incidence than (GB) in consecutive seasons. In cv. So-Jung, head rot and basal rot diseases were the most predominant in both GA and GB. In cv. Bimoran, symptoms of head rot confirmed that this was the most severe disease in both fields. In fact, two diseases—head rot and basal rot—were caused by Alternaria sp. (head rot), Fusarium oxysporum (basal rot), respectively. Mycological characteristics and multiplex PCR-based molecular diagnosis methods confirmed the pathogens for each disease.