Reaction of Select Peanut (Arachis hypogaea L.) Lines to Southern Stem Rot and Pythium Pod Rot Under Varied Disease Pressure

Abstract

Eight breeding lines, three parents, and the cultivar Florunner were compared under two levels of disease pressure indbced by Sclerotium rolfsii Sacc., or Pythiurn rnyriotylurn Drechs. at each of two locations for three years to ascertain the effectiveness of the host plant resistance to each pathogen. Varied disease pressures were created by application of fungicides and supplement of fungal inoculum. Mean Florunner pod yields varied more than 1000 kg/ha as a result of the S. rolfsii treatments but the yields of the resistant TAG-3 were not affected. Disease incidence, as measured by frequency of S. rolfsi infection sites and diseased pods, was much higher for Florunner than TxAG-3. Breeding lines for which TxAG-3 was a parent sustained significant yield reductions. The disease incidence in these lines was higher than the resistant parent, equal or less than Tamnut 74, their other parent, and less than Florunner. The grades of TxAG-3 and its derivatives were lower than Florunner. Pod rot incidence differed for the P. rnyriotylurn treatments but pod yields were not different. TxAG-3 and Toalson sustained less pod disease than Florunner and Tamnut 74. The percent of diseased pod tissue for one derivative of Toalson was lower than Toalson and TxAG-3, and that of one TxAG-3 derivative was equal to its best parent. The breeding lines varied in reaction to the two diseases and some lines showed considerable resistance to both organisms.

Variation in Yield and Resistance to Southern Stem Rot Among Peanut (Arachis hypogaea L.) Lines Selected for Pythium Pod Rot Resistance1

“…Pod disease ratings for the four FlorunnerlPI 365553 runner selections averaged 1.8 compared to 1.6 for the five PI 365553!famnut 74 lines ( Table 2). The wide range in number ofloci, in both runner and spanish lines selected for Pythium pod rot resistance, concurs with our earlier observation that resistance to S. rolfsii and P. myriotylum are not a result of the same defensive mechanisms (20). The coincidental resistance to both pathogens by TxAG-3 adds attraction to its use as a parent.…”

“…Partial resistance ofToalson has been reported by several researchers (6,19,20). Smith and coworkers (20) reported that resistance of TxAG-3 was considerably better than Toalson.…”

“…Smith and coworkers (20) reported that resistance of TxAG-3 was considerably better than Toalson. They also noted partial resistance to S. rolfsii with Tx798716 and Tx 798396, the latter being a derivative of PI 365553.…”

Management ofSclerotium rolfsii‐caused stem and pod rots of groundnut—a critical review†

“…Although no genotypes are known to be immune or even highly resistant to S. rolfsii, several genotypes and breeding lines have been found to show lower than average susceptibility to stem rot'pod rot under field conditions (Wynne and Beute, 1983;Beute etal., 1986;Arnold etal., 1988;Smith et al, 1989;Brenneman etal., 1990;Grichar and Smith, 1992). Of several genotypes reported as partially resistant (NC 2, NC Ac 18016, NC8C, Toalson and Southern Runner), resistance of Toalson has been confirmed by several researchers (Simpson etal., 1979, Branch andCsinos, 1987;Smith etal., 1989).…”

“…Comparative reactions of certain genotypes have varied between greenhouse and field evaluations; for example NC 2 and NC Ac 18016 which showed resistance to S. rolfsii in the field were less resistant in inoculation tests in the greenhouse, while for other genotypes Garren, 1964;Beute etal., 1986;Shew et al, 1987Simpson etal., 1979Csinos, 1987 * Wynne andBeute, 1983;Beute et al, 1986;Shew et al, 1987Wynne and Beute, 1983Shew et al, 1987Arnold et al, 1988Jacob! and Backman, 1989Beute et al, 1986Brenneman etal., 1990Smith et al, 1989Grichar and Smith, 1992Grichar and Smith, 1992Branch and Brenneman, 1993 "Also resistant to pod rot caused by Pythium myriotylum and Rhizoctonia solani. b Also resistant to Cylindrocladium black rot c Also resistant to Pythium pod rot.…”