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Characterization and Pathogenic Relationships of Rhizoctonia solani Isolates in a Potato–Rice System and their Sensitivity to Fungicides
Author(s) -
Thind Tarlochan S.,
Aggarwal Rohit
Publication year - 2008
Publication title -
journal of phytopathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.53
H-Index - 60
eISSN - 1439-0434
pISSN - 0931-1785
DOI - 10.1111/j.1439-0434.2008.01421.x
Subject(s) - rhizoctonia solani , biology , fungicide , propiconazole , horticulture , hypha , rhizoctonia , veterinary medicine , botany , medicine
Potato is planted after rice in several parts of Punjab in India and both crops are attacked by Rhizoctonia solani Kühn. Potato tubers showing black scurf and rice plants affected by sheath blight were collected from different regions of the state and the isolates of R. solani so obtained were studied to determine their variability and to ascertain their cross‐infectivity and response to fungicides. Potato isolates of R. solani did not infect rice plants but some rice isolates were weakly pathogenic on potato, the sclerotia being less firmly attached on tuber surface, indicating a possible unsuccessful attempt of rice isolates to infect potato. Rice isolates (66.6%) grew faster (>20 mm colony growth per 24 h) than those of the potato isolates (15–20 mm growth rate per 24 h). Hyphal width of isolates from both hosts varied from 7.2 to 12.1 μm. Colony growth of most potato isolates (61.2%) was appressed, whereas that of most rice isolates (53.3%) was fluffy. Rice isolates (73.3%) formed larger sclerotia (1.5–2.0 mm in diameter) than those of the potato isolates (0.5–1.0 mm in diameter). Anastomosis studies indicated that potato isolates belonged to AG‐3 and AG‐5 groups while rice isolates belonged to the AG‐1‐1‐A group. Representative R. solani isolates from the two hosts showed significant variation in response to fungicides (i.e. carbendazim, carboxin, pencycuron, propiconazole and validamycin) based on their ED 50 and ED 90 values.