AGRIVITA Journal of Agricultural Science. 2019. 41(3): 405-415 AGRIVITA Journal of Agricultural Science www.agrivita.ub.ac.id 405 INTRODUCTION Chrysanthemum (Dendranthema grandifora Tzvelev syn. Chrysanthemum morifolium [Ramat.] Kitam) is one of the most important ornamental crops in the world. It is typically used as cut fowers or potted plants. It exhibits various colors such as white, yellow, red, purple and pink, but lack of bright red and blue fowers (He, Ke, Keting, Qiaoyan, & Silan, 2013). In international market, this commodity is positioned as the frst occupying more than 35% of the world’s marketed cut fowers and the second is rose. Several European and American countries like Netherlands, Italy, Columbia, Spain, Germany and USA have been known to be the main chrysanthemum producers which supplied more than 60% of the world market request (Plasmeijer & Yanai, 2012). In Indonesia, chrysanthemum is also positioned as the top marketed ornamentals in domestic market. The production increased from 305.9 million in 2011 to 442.7 million stalks in 2015 as a result from the increase of harvested area from 881.2 ha in 2011 to 1,087.2 ha in 2015 (Ministry of Agriculture Republic of Indonesia, 2016). The production process however, is still constrained by several factors, particularly in traditional famers. Disease attacks especially white rust is known to be the most prominent problem to make chrysanthemum production become more effcient and proftable. The disease is caused by an obligate parasitic fungus Puccinia horiana P. Henn (Basidiomycetes). These pathogenic fungus have been known to infect 12 species including chrysanthemum, Nipponanthemum and Leucanthemella (Alaei et al., 2009). The production lost due to these fungus might reach 80% as reported in Turkey and India during the outbreak seasons (Dheepa, Renukadevi, Vinod Kumar, & Nakkeeran, 2015; Göre, 2008). The disease intensity and severity depended on genotype resistances and environmental conditions. High humidity coupled with warmer temperature might induce a conducive ARTICLE INFO Keywords: Chrysanthemum Cladosporium Mycoparasite Puccinia horiana Article History: Received: March 16, 2018 Accepted: July 11, 2019 * ) Corresponding author: E-mail: evinugraha99@yahoo.com ABSTRACT Cladosporium is a promising mycoparasite to control white rust disease in chrysanthemum. The research was conducted to evaluate several collected Cladosporium isolates against P. horiana, their parasitism mechanism and population dynamic in a production cycle. The experiment was carried out at the Indonesian Ornamental Crops Research Institute (IOCRI) from January to December 2015. Ten Cladosporium isolates with two synthetic fungicides and one negative control were designedly sprayed on chrysanthemum cv White Fiji. The results showed that Cladosporium isolates gave varied suppression to white rust intensity. Isolates HNC, DC, SGC and UC had higher parasitism and suppression intensities than other isolates and their effectiveness was the same as synthetic fungicides. Longer fower vase life was produced from Cladosporium and synthetic fungicide treated plants, while fower stalk and diameter were less affected by the Cladosporium applications. The population dynamic of Cladosporium was accordingly responded with the rust intensity in Cladosporium-treated plants. The parasitizing mechanism of Cladosporium to P. horiana was through teliospores envelopment resulted in the changes of teliospores morphology. ISSN: 0126-0537 Accredited First Grade by Ministry of Research, Technology and Higher Education of The Republic of Indonesia, Decree No: 30/E/KPT/2018 Cite this as: Yusuf, E. S., Budiarto, K., & Rahardjo, I. B. (2019). Evaluation of Cladosporium sp. mycoparacites as biocontrol agents of white rust disease on chrysanthemum. AGRIVITA Journal of Agricultural Science, 41(3), 405-415. https://doi.org/10.17503/agrivita.v41i3.1864 Evaluation of Cladosporium sp. Mycoparacites as Biocontrol Agents of White Rust Disease on Chrysanthemum Evi Silvia Yusuf *) , Kurniawan Budiarto and Indijarto Budi Rahardjo Indonesian Ornamental Crops Research Institute, Cianjur, West Java, Indonesia