Market Grade Characteristics Research Articles

Influence of Planting Pattern on Pest Management in Virginia Market Type Peanut (Arachis hypogaea L.)

ABSTRACT Twelve field trials were completed in North Carolina from 2005 to 2007 to determine the impact of planting pattern on peanut yield, market grade characteristics, and pest reaction for the Virginia market type cultivars Perry and VA 98R. The first set of experiments was designed to evaluate incidence of Cylindrocladium black rot (caused by Cylindrocladium parasiticum) using a factorial treatment arrangement of two cultivars, two levels of fumigation (none or metam sodium at 112 L/ha), and two levels of planting pattern (single rows spaced 91-cm apart or twin rows spaced 18 cm apart on 91-cm centers). Visible symptoms associated with Cylindrocladium black rot were not affected by planting pattern. However, in 1 of 3 trials pod scarring as a result of feeding by southern corn rootworm (Diabrotica undecimpunctata Howardi) was greater in twin rows compared with single rows. Damage from tobacco thrips (Frankliniella fusca) was also higher in the cultivar VA 98R planted in twin rows than in single rows or for the cultivar Perry. In the second set of experiments designed to evaluate incidence of Sclerotinia blight (caused by Sclerotinia minor), a factorial treatment arrangement consisting of two cultivars, two levels of boscalid (none or boscalid at 0.44 kg ai/ha), and two levels of planting pattern was implemented. Boscalid decreased Sclerotinia blight incidence at one of 4 locations, and increased pod yield. Yield of Perry was lower when grown in twin rows versus single rows, but yield of VA 98R was higher in twin rows. Peanut planted in twin rows yielded more than peanut planted in single rows regardless of cultivar, fumigation, or disease history in most trials. Results from these experiments suggest that planting pattern can have a minor impact on response to pests and that yield and market grades are often improved when peanut is planted in twin-row planting patterns compared with single rows.

Response of the Peanut (Arachis hypogaea L.) Cultivar Gregory to Interactions of Digging Date and Disease Management

Digging date can have a major impact on pod yield, market grade characteristics, and economic return of peanut (Arachis hypogaea L.) and can be influenced by environmental conditions and disease management. In 17 experiments from 2003 to 2012, economic return of peanut was determined over 5 digging dates spaced 1 week apart beginning in early to mid-September through mid-October. Linear, quadratic, and cubic relationships for economic return versus days after peanut emergence were observed in 3, 6, and 4 experiments, respectively, with no response to digging date observed in 4 experiments. In a second experiment from 2005 to 2012, relationships among canopy defoliation and economic return for peanut at 3 digging dates with 3 fungicide regimes were variable, although increasing the number of fungicide sprays decreased canopy defoliation and increased economic return for later digging dates. Applying a single late-season spray of fungicide as a rescue treatment reduced canopy defoliation in 4 of 8 years and affected economic value in 2 of 8 years.

Peanut (Arachis hypogaea L.) Response to the Ethylene Binding Inhibitor 1-Methylcyclopropene

Abstract Senescence and abscission of mature peanut pods is controlled by the ethylene cascade. Reducing senescence and abscission could involve inhibiting the ethylene cascade and allow greater harvest flexibility in peanut. Application of 1-methylcyclopropene (1-MCP), the ethylene binding inhibitor, may reduce senescence and abscission of mature peanut pods. Research was conducted from 2005 through 2008 in North Carolina to determine the effects of 1-MCP on pod yield and percentages of sound mature kernels (%SMK), sound splits (%SS), total sound mature kernels (%TSMK), other kernels (%OK), extra large kernels (%ELK), fancy pods (%FP), and pod retention. Treatments of 1-MCP were applied at 26 g ai/ha plus a crop oil concentrate at 7, 10, or 14 d prior to digging peanut at the projected optimum digging date. Peanut was dug at the projected optimum digging date or at 7 or 20 d after projected optimum digging date. The cultivars NC-V 11 (2005 and 2007), Phillips (2006 and 2007), and Perry (2008) were evaluated in separate experiments. Pod yield, %SMK, %TSMK, %SS, %OK, %ELK, and %FP were not affected by 1-MCP regardless of application timing when NC-V 11 and Phillips were evaluated. Only %SMK and %TSMK were affected by 1-MCP when applied to the cultivar Perry. Digging date affected pod yield and market grade characteristics. When digging of Phillips and Perry was delayed by 7 or 20 d past the optimum digging date, %SMK and %TSMK increased. Pod retention, determined by comparing the number and mass of pods/plant following digging, was affected by digging date and location but not 1-MCP treatment. These data suggest that 1-MCP will have little activity on peanut pod yield, market grade characteristics, or pod retention.

Peanut Cultivar Response to Damage from Tobacco Thrips and Paraquat

Virginia market‐type peanut cultivars in North Carolina vary in the number of days following emergence required to reach optimum maturity, and concern over cultivar response to interactions of tobacco thrips (Frankliniella fusca Hinds) damage in absence of in‐furrow insecticide and injury from paraquat exist with respect to cultivar selection. Experiments were conducted during 2007 and 2008 to determine if cultivars vary in response to interactions of the insecticide aldicarb (no aldicarb or aldicarb applied in the seed furrow at planting) and the herbicide paraquat (no paraquat or paraquat applied 24 to 28 d after peanut emergence, DAE). The cultivar VA 98R expressed more damage from tobacco thrips than the cultivars Gregory, Perry, or Phillips. Although vegetative growth parameters varied among cultivar, aldicarb, and paraquat treatments, pod yield and market grade characteristics were not affected by the interaction of experiment, cultivar, aldicarb, and paraquat or the interaction of cultivar, aldicarb, and paraquat. Damage from tobacco thrips in absence of aldicarb affected pod yield more than injury from paraquat. The combination of tobacco thrips damage in absence of aldicarb and injury from paraquat lowered pod yield compared with aldicarb‐treated peanut either with or without paraquat regardless of cultivar. These data suggest that recommendations on use of aldicarb for tobacco thrips control or paraquat for early season weed control should not vary based on cultivar selection when considering pod yield and market grade characteristics.

Peanut Yield and Grade Responses to Timing of Bahiagrass Termination and Tillage in a Sod-based Crop Rotation

Abstract Rotation of row crops with perennial grasses has been shown to improve soil quality characteristics, decrease pest incidence, and increase crop yield. Experiments were conducted in Florida during 2006 and 2007 at Marianna and Quincy to determine effects of termination date and subsequent tillage of established bahiagrass (Paspalum notatum L.) on peanut (Arachis hypogea L.) yield and market grade characteristics when rotating from bahiagrass to a row crop. Treatments included two bahiagrass termination dates (fall vs. spring) and six tillage methods [strip-till (in-row subsoiling), disk plus moldboard plow, disk plus chisel, disk plus paratill plus strip-till, disk, and strip-till with 45 kg N/ha]. Bahiagrass termination timing did not affect soil mechanical resistance, peanut yield or market grade characteristics, including percentages of sound mature kernels, split kernels, other kernels, and hulls. Although significant differences in soil mechanical resistance were detected among tillage treatments, peanut yield did not differ among the tillage methods except for the disk alone in 2007 at Quincy. Strip-till peanut yield did not respond to N application. When pooled over termination timing, peanut yields in strip-till, disk plus moldboard plow, disk plus chisel, disk plus paratill plus strip-till, disk, and strip-till plus 45 N were 4830, 5000, 4810, 4810, 4770, and 4620 kg/ha, respectively. These results indicate that when using perennial grasses in sod-based rotations, farmers have a wide window from fall to spring to terminate bahiagrass for optimum peanut production regardless of tillage system.

Factors Influencing Response of Virginia Market Type Peanut (Arachis hypogaea) to Paraquat under Weed-Free Conditions

Abstract Experiments were conducted during 2003 and 2004 to determine if peanut yield and market grade characteristics differed when paraquat was applied 24 to 28 days after emergence to peanut seeded in early, mid-, and late May and early June. Peanut pod yield and percentages of extra large kernels, total sound mature kernels, and farmer stock fancy pods were affected by planting date and paraquat independently. Paraquat did not affect yield compared with non-treated peanut regardless of planting date. In other experiments from 2003–2005, peanut was planted with or without aldicarb in the seed furrow and followed either paraquat applied 24 to 28 days after emergence or 2,4-DB applied in mid-August during 2003 and 2004. In 2005, experiments included a no-paraquat control rather than 2,4-DB. Pod yield was reduced at 3 of 9 sites due to damage from tobacco thrips, Franklinella fusca Hinds, feeding when aldicarb was not applied. Paraquat reduced yield in 4 experiments during 2005 but not in 5 experiments during 2003–2004. Aldicarb and paraquat affected peanut independently. Experiments were also conducted during 2005 and 2006 to compare interactions of paraquat formulations alone or with co-applied herbicides. Paraquat formulation (Gramoxone INTEON versus Gramoxone MAX or Firestorm) did not affect peanut response to paraquat, and interactions of paraquat formulation (Gramoxone MAX or Gramoxone INTEON) with bentazon, bentazon plus diclosulam, bentazon plus dimethenamid, bentazon plus imazethapyr, and bentazon plus S-metolachlor was similar to paraquat alone. Peanut injury and pod yield was the same when paraquat (Gramoxone INTEON) was applied alone or with carfentrazone and was similar to carfentrazone alone.

Elevated Carbon Dioxide and Ozone Effects on Peanut: II. Seed Yield and Quality

Many adverse effects of tropospheric O3 on C3 crop plants are ameliorated by elevated concentrations of atmospheric CO2, but the extent of the interaction can vary, depending on the species, gas concentrations, and other experimental conditions. A 2‐yr open‐top field chamber experiment was conducted to examine this interaction in peanut (Arachis hypogaea L.) by testing the effects of O3 and CO2 mixtures on yield and seed quality. Treatments were ambient CO2 (375 μmol mol−1) and CO2 additions of approximately 173 and 355 μmol mol−1 in combination with charcoal‐filtered (CF) air (22 nmol O3 mol−1), nonfiltered (NF) air (46 nmol O3 mol−1), and NF air plus O3 (75 nmol O3 mol−1). At ambient CO2, pod number was suppressed 16% in NF air and 44% in elevated O3 Pod and seed mass were not significantly affected in NF air but were lowered 33 to 37% in elevated O3 Elevated CO2 increased yield parameters 7 to 17% for plants grown in CF air and restored yield in NF air and elevated O3 treatments to control or higher levels. Gas treatment effects on peanut market grade characteristics were small. No treatment effects were observed on the protein and oil contents of seeds, but there were changes in fatty acid composition. Overall results indicate that increasing concentrations of tropospheric O3 will suppress yield of O3–sensitive peanut cultivars, while elevated CO2 will moderate this response. Elevated O3 and CO2 are not expected to have major effects on peanut seed composition and quality.

Peanut Response to Planting Pattern, Row Spacing, and Irrigation

Experiments were conducted from 1999 through 2002 in North Carolina to compare interactions of planting pattern, plant population, and irrigation on peanut (Arachis hypogaea L.) pod yield and market grade characteristics. In additional experiments, pod yield and severity of tomato spotted wilt tospovirus associated with the cultivars NC‐V 11, NC 12C, VA 98R, and Perry were compared in single row (rows spaced 91 cm apart) and standard twin row (two rows spaced 18 cm apart on 91‐cm centers) planting patterns when peanut was dug and vines inverted on two digging dates spaced 10 to 16 d apart. In a third set of experiments, pod yield, market grade characteristics, and severity of tomato spotted wilt tospovirus were compared when the cultivars NC‐V 11 and Perry were planted in single row, standard twin row, and narrow twin row (two rows spaced 18 cm apart on 46‐cm centers) planting patterns. Peanut pod yield was higher in standard twin row planting patterns than when grown in single row planting patterns in some but not all experiments. Planting peanut in the narrow twin row pattern did not increase peanut pod yield over the standard twin row planting pattern. Less tomato spotted wilt was observed in standard or narrow twin row planting patterns compared with single row planting patterns. Planting peanut in single rows spaced 46 cm apart did not improve yield over peanut planted in single rows spaced 91 cm apart or the standard twin row planting pattern, regardless of irrigation treatment.

Effect of Cultivar and Plant Population on Spotted Wilt in Virginia Market-Type Peanut

Abstract Field experiments were conducted in North Carolina during 2001 and 2002 to evaluate the impact of cultivar and plant population on the incidence of symptoms of tomato spotted wilt virus, which is transmitted primarily by tobacco thrips [Frankliniellafusca (Hinds) (Thysanoptera: Thripidae)]. Treatments included the Virginia market-type cultivars Gregory, NC-V 11, and Perry seeded at in-row plant populations of 7, 13, and 17 plants/m. In these experiments, there was a consistent trend for increased foliar injury from thrips as plant population decreased. Less thrips feeding injury was noted for Gregory and Perry than for NC-V 11. Incidence of visual symptoms of spotted wilt (SW) was recorded from mid-June through mid-September. A plant condition rating was recorded late in the season. Consistent with the results for thrips-induced injury, the percentage of plants infected with SW and the plant condition rating increased as plant population decreased. Gregory had the lowest SW incidence, while NC-V 11 was intermediate between Gregory and the most susceptible Perry. Establishing higher plant densities and planting Gregory rather than NC-V 11 or Perry reduced SW incidence and plant condition rating. Gregory had consistently the highest %ELK (extra large kernels) and %FP (fancy pods) across treatments and locations whereas no definitive trend in market grade characteristics were noted among treatments. In some cases, Perry had a higher incidence of SW, but still had higher pod yields than NC-V 11 with a lower incidence of SW. However, in most cases pod yield correlated with plant condition ratings, and as thrips injury increased, pod yield decreased.

Disease Management in Overhead Sprinkler and Subsurface Drip Irrigation Systems for Peanut

Experiments were conducted during 2001 and 2002 at one location in North Carolina to compare development of early leaf spot (Cercospora arachidicola Hori), pod yield, and market grade characteristics when peanut (Arachis hypogea L.) was grown under overhead sprinkler irrigation (OSI) and subsurface drip irrigation (SDI) and fungicides were not applied or applied biweekly or based on weather advisories. Incidence of early leaf spot was lower when peanut was grown under SDI compared with OSI when fungicides were not applied. Fewer fungicide applications were needed when applications were based on weather advisories rather than when applied biweekly. There was no difference in early leaf spot control or leaf defoliation resulting from disease when fungicides were applied regardless of irrigation system or fungicide application approach. Pod yield was higher in 2001 under SDI compared with OSI when fungicides were not applied; yield was similar in 2002. Disease severity was much higher in 2001 than in 2002 and most likely explains differences in pod yield between years. No difference in yield was noted when fungicides were applied, regardless of irrigation system. The percentage of extra large kernels (%ELK) was lower in 1 of 2 yr under SDI compared with OSI. There were no differences in percentages of fancy pods (%FP), sound splits (%SS), and other kernels (%OK) among irrigation systems and fungicide programs. In a separate experiment where fungicides were applied biweekly, pod yield, %FP, and %ELK were similar under SDI and OSI but greater than nonirrigated peanut. The %OK was lower when peanut was irrigated.

Consistency of Rank Correlations of Peanut Breeding Lines for Market Grade Characteristics and Yield

The genetic potential of peanut (Arachis hypogaea L.) breeding lines for pod yield can only be determined after testing in several environments. Limited data are published on the influence of the environment on peanut market grade characteristics. The objective of this study was to determine the amount of evaluation needed to rank market‐grade characteristics in peanut. Rank correlations for pod yield, 100‐ seed weight, shelling percentage, and total sound mature kernel (TSMK) proportion were calculated between replications, between harvest dates, and between locations for a range of genotypes in 60 tests. Rank correlations for pod yield between locations ranged from −0.48 to 0.77 and were not significant in more than half the tests. Shelling percentage correlations ranged from 0.69 to 0.96 and 100‐seed weight correlations ranged from 0.78 to 0.98 and were all highly significant. The TSMK correlations were less frequently significant and ranged from 0.39 to 0.90. Similar observations were made between replications and between harvest dates. Thus, relative genotypic expression in peanut for seed weight and shelling percentage is consistent in different environments. Decisions to discard or retain peanut lines in a breeding program may be based on acceptable seed size or shelling percentage after limited testing.