Submitted to: Proceedings of the International Sclerotinia Workshop
Publication Type: Proceedings
Publication Acceptance Date: 1/1/2003
Publication Date: 1/21/2003
Citation: CHEN, W., GRUNWALD, N.J., MCPHEE, K.E., MUEHLBAUER, F.J. EVALUATION OF LENTIL CULTIVARS FOR RESISTANCE TO WHITE MOLD. PROCEEDINGS OF THE INTERNATIONAL SCLEROTINIA WORKSHOP. 2003. p. 17. Interpretive Summary: Sclerotinia white mold could be an important disease of lentils under conditions conducive to the disease. Yet little information is available about white mold of lentils. This study was initiated to gain understanding of lentil resistance to the white mold pathogen Sclerotinia sclerotiorum. Commercial cultivars and advanced breeding lines were screened in the greenhouse and also in the filed. Several cultivars like Palouse and Pardina were found to be among the most susceptible, whereas cultivars Merritt and Pennel appeared to be relatively resistant to white mold. This study provides baseline information about lentil resistance to white mold.
Technical Abstract: Greenhouse and field experiments were conducted in 2002 to evaluate cultivars of lentil for resistance to Sclerotinia white mold. Sixteen entries (15 cultivars and one advanced breeding line) were evaluated at the Spillman Farm of Washington State University in Pullman, WA. The treatments were arranged in a randomized complete block design with four replications. Each plot was 8 ft square with a 4-ft alley between plots. Entries were double planted in two directions to create a microenvironment favoring development of white mold. The plots were inoculated twice. First inoculation was on 12 June using cold-treated sclerotia recovered from dry pea screenings. The pre-treatment consisted of placing sclerotia inoculum in a 4'C cold room for nine weeks. Four hundred fifty milliliter of the sclerotia was hand spread over each plot. A second inoculation was carried out using colonized oat kernels on 1 July. Two liters of 2-wk old colonized autoclaved oat kernels were thoroughly mixed with greenhouse soil, and the mixture was evenly spread over the plot area (each plot received the same amount of inoculum equivalent to 25 ml colonized oat kernels). Disease severity ratings were taken on 9 July and again on 25 July. Because of the dry summer, white mold disease severity was generally low. Nevertheless, differences among the 16 test entries in response to white mold were observed. Cultivars Athena, Mason, Palouse and Pardina were clearly among the most susceptible cultivars. Seven of the tested entries (6 cultivars and one breeding line) showed very little disease and appeared to be relatively resistant to white mold. None of the test entries were immune to white mold. The 16 lentil entries plus four winter lentil lines were evaluated for relative susceptibility to white mold in the greenhouse. Two plants were grown in each pot and three to six replications were used for each entry. Initial trials included two inoculation techniques: the petiole inoculation developed for soybean at University of Wisconsin and colonized oat kernels. The petiole technique worked very well for the lentil lines that branch early in growth habit, and the disease progress can be easily monitored. However, some lentil lines do not have lateral branches. Colonized oat kernels were used to compare all lentil entries in the greenhouse trials. After comparing different levels of inoculum, two colonized oat kernels per plant were chosen as a standard method. Disease pressure was higher in greenhouse than that we observed in the field in 2002. Cultivars Merritt and Pennel were more resistant to white mold than other lentil cultivars. Among the four advanced breeding lines of winter lentils, LC9976079 was the most susceptible.