Evaluation of Ornamental Tropical Plants for Resistance to White Mold Caused by Sclerotinia sclerotiorum

Abstract

<jats:p><jats:italic>Sclerotinia sclerotiorum</jats:italic> (Lib.) de Bary is a fungal pathogen that causes stem rot, crown rot, wilt, and death of many common annual flowering plants. Infested flower beds often suffer significant plant loss each year, and the identification of disease resistant plants would be a useful management tool. Caladium (<jats:italic>Caladium ×hortulanum</jats:italic> Birdsey), canna (<jats:italic>Canna</jats:italic> ×<jats:italic>generalis</jats:italic> L.H. Bailey), and elephant ear [<jats:italic>Colocasia esculenta</jats:italic> (L.) Schott] were evaluated for potential resistance to <jats:italic>S. sclerotiorum</jats:italic>. Plants grown in field conditions in Minnesota in 2012 and 2013 were inoculated through the application of sorghum grains colonized by <jats:italic>S. sclerotiorum</jats:italic>. The number of plants infected and percent of canopy dieback were recorded weekly for 3 months. The susceptibility of leaves, flowers, and below ground storage organs was also examined through direct inoculation of plant tissue with a mycelial plug of the pathogen in controlled environmental conditions favorable for disease development. Symptoms and progression of the infection were recorded after 24 days. Symptoms of infection on all three species were similar in field and controlled environments. Caladium plants were susceptible to <jats:italic>S. sclerotiorum</jats:italic>. Petioles, leaves, and corms developed a watery soft rot. Elephant ear was highly resistant to infection. <jats:italic>Sclerotinia sclerotiorum</jats:italic> infected only wounded or senescent tissue and did not result in significant symptoms under any conditions. Canna had partial resistance to the pathogen. Although canna petals were readily infected, infection of petioles was restricted to small necrotic lesions. Neither infection progressed to the main stem or resulted in plant death. This study indicates that canna and elephant ear have resistance to <jats:italic>S. sclerotiorum</jats:italic> and could be used in an integrated disease management program for infested landscape beds.</jats:p>

A First Report of Sclerotinia sclerotiorum Causing Forsythia Twig Blight in Romania

“…The majority of reports of S. sclerotiorum in ornamental plants come from the commercial production of plants in greenhouses or nurseries [16]. Therefore, less is known about the epidemiology of S. sclerotiorum in ornamental plants grown in natural landscapes [17]. In flowering woody ornamentals, descriptions of disease indicate that ascospores initiate infection through flowers.…”