Chloroacetamide Herbicides and Chlorimuron Do Not Predispose Peanut (Arachis hypogaea) to Stem Rot (Sclerotium rolfsii)1

1994 ◽  
Vol 21 (2) ◽  
pp. 126-129 ◽  
Author(s):  
W. Carroll Johnson ◽  
Timothy B. Brenneman ◽  
Benjamin G. Mullinix

Abstract Field studies were conducted from 1991 through 1993 at Plains, GA to determine the effect of chloroacetamide herbicides and chlorimuron on incidence of stem rot in peanut. The experimental site had a cropping history of more than 25 yr in continuous plantings of peanut and extremely high incidence of stem rot. Incidence of stem rot and peanut yield were not affected (P≤0.05) by chloroacetamide herbicides in 1991, 1992, and 1993. Chlorimuron applied 60 d after emergence had no effect on stem rot incidence or peanut yield. Paired plots treated with thifluzamide had very low stem rot incidence and 27% greater peanut yields. Based on these studies, neither chloroacetamide herbicides nor chlorimuron predisposed peanut to stem rot.

1983 ◽  
Vol 10 (2) ◽  
pp. 75-79 ◽  
Author(s):  
A. S. Csinos ◽  
D. K. Bell ◽  
N. A. Minton ◽  
H. D. Wells

Abstract Field experiments evaluating three isolates of Trichoderma harzianum Rifai and a white spored Trichoderma sp. alone and in combination with fungicides and fungicide-insecticide/nematicide combinations were conducted during 1979-81 in an area with a history of high incidence of Sclerotium rolfsii Sacc. None of the Trichoderma sp. treatments alone, mixed with wheat middlings, or combined with carboxin reduced disease or increased yield over the control; however, disease was reduced when T. harzianum was applied with PCNB at 11.2 kg/ha. Trichoderma spp. appeared to be active only over a 3-8 day period, which was inadequate for control of S. rolfsii for the entire season. Treatments containing PCNB (11.2 kg ai/ha) alone or with the insecticide/ nematicides ethoprop (3.4 kg ai/ha), fensulfothion (3.4 kg ai/ha), and aldicarb (1.7 kg ai/ha) significantly increased yields 9 of 12 times with an average increase of 790 kg/ha; and significantly reduced disease loci at harvest 5 of 12 times with an average reduction of 36%. Ethoprop 10G alone at 3.4 kg ai/ha increased yield one of 3 times, but did not reduce disease. Aldicarb and phenamiphos alone did not decrease disease or increase yield. Carboxin 4G decreased disease and increased yield only when applied at 1.12 kg ai/ha six times on an as required basis. Carboxin 3F at 0.84 kg ai/ha applied 6 times and carboxin 75W at 1.27 kg ai/ha applied one time did not increase yield or reduce disease at harvest.


1985 ◽  
Vol 12 (1) ◽  
pp. 4-7 ◽  
Author(s):  
B. B. Shew ◽  
M. K. Beute ◽  
J. E. Bailey

Abstract Potential for improved control of southern stem rot caused by Sclerotium rolfsii Sacc.on peanut (Arachis hypogaea L.) was evaluated by combining moderate resistance with fungicide use. Various fungicides including carboxin, oxycarboxin, propiconazol, OAC 3890, and PCNB were applied to peanut lines NC 8C, NC Ac 18016, and Florigiant in North Carolina during 1980, 1981, and 1982. Consistently fewer disease loci occurred on NC Ac 18016 than on NC 8C or Florigiant. At least one fungicide reduced stem rot incidence in two of three years tested, but fungicide use did not result in greater yields. Effects of disease resistance and fungicides on suppression of stem rot development were additive.


1990 ◽  
Vol 17 (2) ◽  
pp. 65-67 ◽  
Author(s):  
T. B. Brenneman ◽  
W. D. Branch ◽  
A. S. Csinos

Abstract The susceptibility of 16 peanut (Arachis hypogaea L.) genotypes (eight Virginia and eight runner types) to southern stem rot (Sclerotium rolfsii Sacc.) was evaluated in field tests over three years. Mean disease incidence for all cultivars was 10.0, 15.4 and 16.4 disease loci per 12.2 m row and average yields were 3488, 2826 and 3569 kg/ha in 1986, 1987 and 1988, respectively. Disease incidence averaged 14.3 disease loci per 12.2 m of row for both market types. The mean yield for the eight Virginia types was 3287 kg/ha versus 3214 for the eight runner types. Culitvars within market types varied significantly in disease incidence and pod yield. Of the Virginia types, NC 6 and Florigiant were the most susceptible with NC 9, VA 81B and Early Bunch being the most resistant. Incidence of stem rot in runner cultivars was high except for Southern Runner and Langley which had about 50% less disease than the most susceptible entries. There was a highly significant correlation (P≤0.01) between yields and disease incidence all three years. Overall, Southern Runner had the lowest disease incidence and highest pod yield of any cultivar. Compared to Florunner, the current industry standard for runner types, Southern Runner had about 50% less disease and yields were 1346 kg/ha higher.


1989 ◽  
Vol 16 (1) ◽  
pp. 9-14 ◽  
Author(s):  
O. D. Smith ◽  
T. E. Boswell ◽  
W. J. Grichar ◽  
C. E. Simpson

Abstract Eight breeding lines, three parents, and the cultivar Florunner were compared under two levels of disease pressure induced by Sclerotium rolfsii Sacc., or Pythium myriotylum 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 TxAG-3 were not affected. Disease incidence, as measured by frequency of S. rolfsii 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. myriotylum 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.


Plant Disease ◽  
2010 ◽  
Vol 94 (6) ◽  
pp. 683-689 ◽  
Author(s):  
J. Augusto ◽  
T. B. Brenneman ◽  
A. K. Culbreath ◽  
P. Sumner

Chemical control of soilborne peanut (Arachis hypogaea) diseases requires deposition of fungicide on plant tissues near the soil. Four applications of a protectant fungicide, chlorothalonil (1.26 kg a.i./ha), or a systemic, azoxystrobin (0.21 kg a.i./ha), pyraclostrobin (0.21 kg a.i./ha), or prothioconazole (0.08 kg a.i./ha) plus tebuconazole (0.15 kg a.i./ha), were sprayed either (i) early in the morning (3:00 to 5:00 A.M., with folded and wet leaves), (ii) during daylight (10:00 A.M. to 12:00 P.M., with unfolded and dry leaves), or (iii) in the evening (9:00 to 10:00 P.M., with folded and dry leaves). All timings of systemic fungicides provided similar control of foliar diseases. Early-morning applications of pyraclostrobin and prothioconazole plus tebuconazole decreased stem rot (caused by Sclerotium rolfsii) at digging compared with day and evening applications. All systemic fungicides increased yield when applied at early-morning compared with day applications. Spray coverage, density, and droplet size were higher with night than day applications, and differences were more evident in the lower canopy layers. These results suggest that applications made early in the morning to folded, wet leaves can improve spray penetration of peanut canopies, thus improving stem rot control and increasing yield.


1998 ◽  
Vol 25 (2) ◽  
pp. 59-62 ◽  
Author(s):  
W. J. Grichar

Abstract Field studies were conducted from 1987 to 1996 to evaluate the effects of long-term no-tillage, reduced-tillage, or full-tillage systems on peanut grade, yield, and stem rot (Sclerotium rolfsii) disease development. In 3 of 10 yr the full-tillage system outyielded the no-tillage system while the reduced tillage system resulted in yield increase over no-tillage systems in 2 yr. Reduced-tillage plots had a higher incidence of stem rot than full-or no-tillage in 4 of 10 yr. In 3 of 10 yr, peanut grade (% TSMK) was lower in no-tillage than full-tillage plots. The reduced tillage system has shown promise for use in Texas for peanut. However, no-tillage peanut systems have never produced yield and quality comparable to full-tillage systems.


Plant Disease ◽  
2007 ◽  
Vol 91 (3) ◽  
pp. 273-278 ◽  
Author(s):  
L. E. Sconyers ◽  
T. B. Brenneman ◽  
K. L. Stevenson ◽  
B. G. Mullinix

Two field studies were conducted in 2000, 2001, and 2002 to determine the effects of row pattern (91.4-cm single or 20.3-cm twin) and seeding rate (single: 12.5, 17.4, or 22.6 seed m-1or twin: 6.2, 8.9, or 11.5 seed m-1) on peanut stem rot (Sclerotium rolfsii) development. The first study was conducted in a naturally infested field and relative efficacy of azoxystrobin (Abound 2.08 F, applied at a rate of 0.3 kg a.i. ha-1 at 60 and 90 days after planting [DAP]) also was evaluated. In this study, stem rot incidence was significantly greater (P < 0.05) in single rows planted at high seeding rates than in twin rows planted at any of the seeding rates. Row pattern did not affect azoxystrobin efficacy, and disease incidence was nearly half as much in twin rows treated with fungicide than incidence in single rows treated with fungicide. In the second field study, individual peanut plants in fumigated plots were inoculated once with S. rolfsii at 50, 70, or 90 DAP. Stem rot incidence at harvest was significantly greater on plants inoculated 50 DAP than plants inoculated 70 or 90 DAP. The incidence of spread to adjacent rows was higher in plots where plants were inoculated at 50 than at 90 DAP. Plants inoculated 90 DAP had less disease at harvest, but often developed more severe symptoms within the first week after inoculation compared with plants inoculated 50 or 70 DAP. Symptoms were more severe in single than in twin rows, and at the higher seeding rates. Data from these studies suggest that the physical spacing between plants is a critical factor in stem rot development both on individual plants and in plant populations.


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