First Report of Rhizoctonia solani on Mung Bean (Vigna radiata) Sprouts in California

Abstract

In March 2007, mung bean (Vigna radiata) sprouts produced in an indoor sprouting facility in northern California developed brown lesions beginning 5 days after germination. Dark brown-to-reddish brown lesions with distinct margins developed on the stem, hypocotyl, and first true leaves of affected sprouts. Although all seed is routinely soaked in 20,000 mg Ca(OCl)2/liter of water for 15 min before germination, approximately 5 to 10% of the bean sprouts in several growing baskets (1.5 × 1.5 m) were affected and had to be discarded. Each basket contained approximately 1 t of sprouts. To isolate the causal organism, symptomatic stems were surface disinfested for 1 min in 0.5% NaOCl and incubated on acidified potato dextrose agar (PDA) at 25°C. Cultures were identified as Rhizoctonia solani on the basis of morphological features including right-angled branching of brown hyphae and the presence of sclerotia. PCR amplification of the internal transcribed spacer region was performed with primers RS1 and RS4 (2). Sequences were identical to R. solani AG4-HG-II in GenBank (Accession No. AF354074). To conduct pathogenicity tests, a 5-mm2-diameter disk from the margin of a culture of the fungus on PDA was placed in the center of 25 5-day-old germinated sprouts placed in a plastic box (15 × 10 × 5 cm) held at 25°C. Two isolates of R. solani cultured from different lots of sprouts were included in the assays. Controls received noncolonized agar. Treatments were replicated four times and each experiment was repeated three times. A moist paper towel was included in each box to maintain humidity. After 3 days, symptoms developed in the inoculated boxes but not in the noninoculated boxes. The fungus was reisolated from lesions, completing Koch's postulates. To our knowledge, this is the first report of R. solani on mung bean sprouts in a commercial sprouting facility. However, R. solani has been associated with root rot of mung bean plants in the field (1). References: (1) T. R. Anderson. Can. Plant Dis. Surv. 65:1, 1985. (2) C. Guillemaut et al. Can. J. Microbiol. 49:556, 2003.

Evaluation of Efficacy of Different Bioagents and Fungicides against Rhizoctonia solani (Kuhn)

“…This global crop, encounters a number of operational constraints, including pests and diseases that limit its production and yield potentials from seedling to harvest and often provoking grain yield loss of over 35 per cent (Asiwe, 2006). Brien et al, (2008) identified Rhizoctonia solani (Kuhn) on the basis of morphological features as causal pathogen on mungbean. R. solani is known to affect many crops.…”

Rhizoctoniaspp. Causing Root and Hypocotyl Rot inPhaseolus vulgarisin Cuba

“…The binucleate isolates were characterized as AG F (18%) and AG A (2%). Rhizoctonia solani AG 4 and AG 2‐2 isolates have been reported before on common bean (Bolkan and Ribeiro, 1985; Nelson et al., 1996; Fenille et al., 2002; Balali and Kowsari, 2004; Chang et al., 2005; O’Brien et al., 2008). Binucleate Rhizoctonia isolates have been studied less, but AG F and AG A have also been reported before on bean (Eken and Demirci, 2004; Yang et al., 2005).…”

Serangan Cendawan Sclerotium rolfsii Pada Beberapa Varietas Kedelai yang Ditanam di Beberapa Sistem Tanam Kelapa / Damage of Sclerotium rolfsii Fungus on Saveral Varieties of Soybean Planting Under Coconut Palm

“…S. rolfsii sulit dikendalikan karena patogen mampu mempertahankan dirinya pada tanah dalam bentuk struktur istirahat pada kondisi tanah yang ekstrim dan mampu bertahan selama lebih dari 10 tahun. Cendawan S. rolfsii tercatat mempunyai kisaran inang yang luas, terutama menyerang tanaman muda seperti pada tanaman kedelai (O'Brein et al, 2008). Perkembangan dan penyebaran inokulum penyakit dilapangan sangat dipengaruhi oleh faktor abiotik seperti suhu, kelembaban dan termasuk keadaan tanah.…”