Occurrence of Pod Rot Pathogens in Peanuts Grown in North Carolina

Abstract

Pod rot diseases historically caused significant losses in peanut production in North Carolina. Advances in the understanding of pod rot diseases and changes in cultural practices minimized losses in the years since 1979. By the early 1990s, however, some peanut growers began to observe pod rot that apparently was not associated with infection by common soilborne pathogens. Incidence of pod rot also was high in research plots used to study conservation tillage methods. Selected farms were surveyed in the fall of 1994, 1995, and 1996 to identify the fungi associated with pod rot symptoms in North Carolina. Over the three years of the study, more than 6,000 symptomatic pods from 125 peanut fields were assayed for Rhizoctonia spp., Pythium spp., Cylindrocladium parasiticum, Sclerotium rolfsii, and Sclerotinia minor. All five pathogens were isolated during the field survey, with Pythium spp. and Rhizoctonia spp. isolated most frequently. Rhizoctonia spp. were the dominant pathogen in the majority of fields in 1994, whereas Pythium spp. predominated in 1995 and 1996. Combinations of pathogens were identified from 12 to 15% of pods; Rhizoctonia spp. + Pythium spp. and Pythium spp. + C. parasiti-cum were the most frequent combinations. The mean estimated incidence of pod rot was 6.6% in 1995 and 5.9% in 1996. The effects of cover crops and tillage on pod rot incidence were studied in microplots in 1995 and 1996. In 1995, winter cover crops (wheat, oat, rye, and fallow soil) did not affect pod rot incidence, but incidence was greater in no-till treatments compared to plots with conventional tillage. Pod rot incidence did not differ among infestation treatments and no interactions among pathogen, cover crop, or tillage treatments were significant. In contrast, significant (P = 0.04) interactions among winter cover crops and tillage occurred in 1996. Tillage did not affect pod rot incidence following wheat or oats, but incidence following rye was much greater in no-till than in tilled plots.

Seed-Borne Fungi of Peanut in Egypt: Pathogenicity and Transmission

“…Sources of seed samples: Fifty seed samples of mixed cultivars of peanut were collected from commercial markets in different parts of Egypt, including Ismailia, Sharkia and Nobaria, during 1996, 1997and 1998.…”

“…Numerous Sclerotium species attack peanut plants, causing a considerable loss in yield. S. rolfsii and S. bataticola have been isolated from peanut in Egypt (El-Khadem at al., 1974;El-Akkad, 1982;Porter et al, 1990;Hollowell et al, 1998). The floury rot disease, caused by Verticillium sp., attacks peanut pods at a later stage of maturity and has been isolated from seeds (Frezzi, 1965;Mathur et al, 1975;Melouk et al, 1983).…”

“…The floury rot disease, caused by Verticillium sp., attacks peanut pods at a later stage of maturity and has been isolated from seeds (Frezzi, 1965;Mathur et al, 1975;Melouk et al, 1983). Rhizoctonia solani is the most prevalent fungus associated with mature sound or rotted pods, and is the major causal organism of seedling damping off (Abou-Talib, 1970;Tawfik 1975;El-Khadem et al, 1974;El-Akkad, 1982;Porter et al, 1990;Richardson, 1990;Baird et al, 1993;Hollowell et al, 1998). Fusarium spp.…”

Microorganisms Associated with Valencia Peanut Affected by Pod Rot in New Mexico

“…Under favorable environmental conditions, Rhizoctonia pod rot, caused by R. solani, can decrease yield by 22 to 28% (Besler et al, 2003). In fields surveyed in North Carolina for pod rot pathogens over a 3-year period, Hollowell et al (1998) found that Rhizoctonia spp. and Pythium spp.…”

Irrigation Rate and Fungicide Effects on Peanut Kernel Damage, Yield, and Net Return

“…Pod rot was found to cause considerable losses in Israel (Frank, 1968). In North Carolina, pod rot was estimated at 6 to 7% in 1995 and 1996 (Hollowell, et al, 1998). In both North Carolina (Hollowell et al, 1998) and the High Plains of Texas (Wheeler et al, 2006), Rhizoctonia spp.…”