ABSTRACTyield, improve some market grade characteristics, and decrease incidence of tomato spotted wilt tospovirus Experiments were conducted from 1999 through 2002 in North(TSWV) (Baldwin and Williams, 2002;Hurt et al., 2003). Interactions of planting pattern and seeding rate with irrigation have been reported for several crops. Irrigation increased corn (Zea mays L.) yield when higher A ltering plant population and row pattern can afplant populations were established compared with lower fect crop yield, quality factors, and pest developplant populations when row pattern was held constant ment in peanut. Pod yield of bunch-type peanut was (Liang et al., 1992). In contrast, corn yield did not in-16% higher when peanut was seeded in rows spaced crease when plant population was increased in absence 46 cm apart compared with 91 cm (Norden and Lipsof irrigation (Liang et al., 1992). In soybean [Glycine comb, 1974). Duke and Alexander (1964) reported pod max (L.) Merr.], increasing plant populations and deyield that was 14% higher in narrow row plantings comcreasing row width increased yield (Lehman and Lampared with traditional wider row patterns using largebert, 1960). In cotton (Gossypium hirsutum L.), yield seeded Virginia bunch-type peanut. Spanish market increases were noted when seeding rate was increased type peanut planted in 46-cm rows yielded higher than and row spacing was decreased (Briggs et al., 1967; Heitpeanut planted in rows spaced 61, 76, 91, or 107 cm apart holt et al., 1992;Hoskinson et al., 1974). at similar in-row plant populations (Parham, 1942). Cox Determining interactions of seeding rate and planting and Reid (1965) reported that increasing plant populapattern with variables such as cultivar selection and tions by increasing in-row seeding rate or by decreasing irrigation will assist growers and their advisors in develrow width increased pod yield.oping efficient production and pest management sysAlthough the majority of peanut in the USA is seeded tems for peanut. Therefore, research was conducted to in single rows spaced 91 to 102 cm apart, research sugcompare peanut pod yield, market grade characteristics, gests that seeding peanut in standard twin row patterns and TSWV severity when peanut was seeded in various (rows spaced approximately 18 cm apart with centers planting patterns, seeding rates, and cultural practices. of these rows spaced 91 to 102 cm apart) can increase MATERIALS AND METHODS

cidence often increases under irrigation, and benefits of increased yield can be minimized due to increased Experiments were conducted during 2001 and 2002 at one location incidence of noncontrolled disease (Rotem and Palti, in North Carolina to compare development of early leaf spot (Cercospora arachidicola Hori), pod yield, and market grade characteristics 1969;Wright et al., 1986). Increased moisture on the when peanut (Arachis hypogea L.) was grown under overhead sprin-soil surface and humidity in the peanut canopy following kler irrigation (OSI) and subsurface drip irrigation (SDI) and fungioverhead irrigation can increase incidence of Sclerotinia cides were not applied or applied biweekly or based on weather blight (Sclerotinia minor), pod rot (Pythium myriotylum), advisories. Incidence of early leaf spot was lower when peanut was and leaf spots (Cercospora arachidicola and Cercosporigrown under SDI compared with OSI when fungicides were not apdium personatum) (Wright et al., 1986). plied. Fewer fungicide applications were needed when applicationsSubsurface drip irrigation has been evaluated in a were based on weather advisories rather than when applied biweekly. variety of agronomic and vegetable crops (O'Brien etThere was no difference in early leaf spot control or leaf defoliation al., 1998). Subsurface drip irrigation can conserve water resulting from disease when fungicides were applied regardless of while maintaining or increasing peanut yield (Puppala irrigation system or fungicide application approach. Pod yield was higher in 2001 under SDI compared with OSI when fungicides were et al., 2000). It is suspected that disease incidence in peanut not applied; yield was similar in 2002. Disease severity was much would be lower under SDI compared with OSI because higher in 2001 than in 2002 and most likely explains differences in a decrease in the amount and duration of moisture in pod yield between years. No difference in yield was noted when the canopy under SDI would lessen the likelihood of fungicides were applied, regardless of irrigation system. The percentdisease development. Cost of installation of SDI and age of extra large kernels (%ELK) was lower in 1 of 2 yr under SDIOSI depends upon field size, topography, and cropping compared with OSI. There were no differences in percentages of systems (Bosch et al., 1992;O'Brien et al., 1998). Initial fancy pods (%FP), sound splits (%SS), and other kernels (%OK) and long-term investment in either system is similar among irrigation systems and fungicide programs. In a separate experi- (O'Brien et al., 1998). Less disease and more efficient ment where fungicides were applied biweekly, pod yield, %FP, and water use make SDI an attractive alternative to OSI. %ELK were similar under SDI and OSI but greater than nonirrigated peanut. The %OK was lower when peanut was irrigated.

Diclosulam is generally applied either PPI or PRE to peanut to control certain broadleaf weeds and suppress sedges. Research was conducted to determine efficacy and peanut response to POST applications of diclosulam at 9, 13, 18, and 27 g ai/ha. Efficacy of diclosulam was affected by application rate and environment. Common ragweed control ranged from 60 to 100%, entireleaf morningglory control from 56 to 100%, marestail control from 78 to 85%, and nodding spurge from 50 to 97%. Smooth pigweed and common lambsquarters were both controlled less than 35%. Diclosulam controlled yellow nutsedge and eclipta less than 70 and 80%, respectively. In separate experiments, diclosulam and imazapic controlled dogfennel more effectively than acifluorfen, bentazon, imazethapyr, lactofen, paraquat, or 2,4-DB. Visual estimates of peanut injury were 15% or less for all rates during both years. Peanut yield ranged from 3,340 to 3,730 kg/ha in 2002 and 5,230 to 5,820 kg/ha in 2003. Foliar injury and peanut pod yield were influenced by diclosulam rate, although no clear relation was evident. Cultivar and diclosulam rate did not interact with respect to visual injury or pod yield.

Peanut digging efficiency is often reduced due to excessive vine growth. The plant growth regulator prohexadione calcium retards vegetative growth and improves row visibility by inhibiting internode elongation resulting in improved digging efficiency and in some instances increases in pod yield. The objective of this research was to determine the effects of prohexadione calcium on row visibility and pod yield of newly released and commercially available cultivars AT VC-2, Brantley, CHAMPS, Georgia Green, Gregory, Perry, Phillips, NC-V 11, NC 12C, Tamspan 90, and VA 98R and the breeding lines N02006, N01013T, and VT 976133. Although differences in row visibility were noted among cultivars, prohexadione calcium improved row visibility in almost every experiment regardless of cultivar. The cultivars NC 12C and Perry were more responsive to prohexadione calcium in terms of pod yield than NC-V 11 or VA 98R. Response of these cultivars was independent of digging date. In other experiments, prohexadione calcium improved row visibility of the cultivars AT VC-2, Gregory, NC-V 11, Perry, VA 98R, and Wilson, but did not increase yield when compared with non-treated peanut. In a final experiment, prohexadione calcium improved row visibility of the Virginia market type cultivars Brantley, CHAMPS, Gregory, and Phillips and the experimental lines N02006, N01013T, and VT 976133. Row visibility for the experimental line N01013T was improved at 2 of 4 sites by prohexadione calcium. In a final experiment, prohexadione calcium increased row visibility of Georgia Green, Gregory, and Tamspan 90 but did not affect pod yield of these cultivars.

Experiments were conducted from 2000 through 2003 in North Carolina to compare peanut (Arachis hypogaea L.) response to inoculation with Bradyrhizobium In one study that included 20 experiments, peanut pod yield was compared following no inoculation or inoculation with commercial granular or liquid in‐furrow products. In six of these experiments, inoculant was also applied to the seed before planting. In six other experiments within this study, pod yield of inoculated and noninoculated peanut was determined following surface applications of N approximately 40 d after planting. In a second study, peanut pod yield was compared in twin row planting patterns (two rows spaced 18 cm apart on 91‐cm centers) when inoculant was applied in‐furrow to one of the twin rows or to both of the twin rows. In a third study, interactions of in‐furrow inoculation and fumigation with metam sodium were compared. Peanut pod yield was higher following inoculation in 7 of 20 experiments. In six of the seven experiments where a yield response to inoculation was observed, peanut had not been planted previously in these fields. In experiments where peanut responded positively to inoculant, pod yield was higher when inoculant was applied in the seed furrow rather than to seed before planting. Nitrogen increased pod yield linearly in three of six experiments (p ≤ 0.05). Inoculating both rows of peanut seeded in twin row patterns yielded higher in two of four experiments than when one of the twin rows was inoculated or when inoculant was not included. Fumigation with metam sodium did not affect pod yield, regardless of inoculation treatment.

Irrigated cotton acreage is limited in North Carolina. Research was conducted in North Carolina from 2004 to 2007 to define interactions of planting date with either mepiquat chloride application or cultivar under sub‐surface drip irrigation or no irrigation. In most instances planting date, cultivar or mepiquat chloride, and irrigation did not interact for seed cotton yield. While main effects of planting date and irrigation were often significant, mepiquat chloride did not affect cotton yield. Cotton response to irrigation and planting date was variable and was generally influenced by annual variability in rainfall. Results from these experiments suggest that sub‐surface drip irrigation improves cotton yield stability over the planting dates, mepiquat chloride applications, and cultivars tested. Additionally, cotton response to planting date was independent of irrigation treatment.

Research was conducted in North Carolina to compare weed control by various rates of imazapic POST alone or following diclosulam PRE. In a second experiment, weed control by imazapic applied POST alone or with acifluoren, diclosulam, or 2,4-DB was compared. In a final experiment, yellow nutsedge control by imazapic alone and with the fungicides azoxystrobin, chlorothalonil, pyraclostrobin, and tebuconazole was compared. Large crabgrass was controlled more effectively by imazapic POST than diclosulam PRE. Common lambsquarters, common ragweed, and eclipta were controlled more effectively by diclosulam PRE than imazapic POST. Nodding spurge was controlled similarly by both herbicides. Few differences in control were noted when comparing imazapic rates after diclosulam PRE. Applying either diclosulam PRE or imazapic POST alone or in combination increased peanut yield over nontreated peanut in five of six experiments. Few differences in pod yield were noted when comparing imazapic rates. Acifluorfen, diclosulam, and 2,4-DB did not affect entireleaf morningglory, large crabgrass, nodding spurge, pitted morningglory, and yellow nutsedge control by imazapic. Eclipta control by coapplication of imazapic and diclosulam exceeded control by imazapic alone. The fungicides azoxystrobin, chlorothalonil, pyraclostrobin, and tebuconazole did not affect yellow nutsedge control by imazapic.

Research was conducted in North Carolina to determine peanut response to flumioxazin as influenced by rate and timing of application and cultivar. Delaying application of flumioxazin from 1 d after planting until peanut emergence increased injury regardless of rate. The Virginia market-type cultivar ‘NC-V 11’ was injured more by flumioxazin than the cultivars ‘Gregory’ or ‘Perry’. However, pod yield was not affected by flumioxazin even though significant injury was observed early in the season regardless of flumioxazin rate, application timing, or cultivar. Diclosulam was more effective than flumioxazin in controlling eclipta when these herbicides were applied PRE with metolachlor or following pendimethalin PPI. However, control by flumioxazin prevented yield loss when compared with metolachlor alone.