Non-treated Peanut Research Articles

Transcriptome and proteome analysis of ultrasound pretreated peanut sprouts

Combined transcriptomic and proteome analyses were carried out to investigate the influence of ultrasound pretreatment on peanut sprouts. In total, 1104 differentially expressed genes (upregulated:538, downregulated:521) and 399 differentially accumulated proteins (upregulated: 197, downregulated: 202) were identified between ultrasound pretreated and nontreated peanut sprouts. These genes and proteins were related to a series of crucial biomolecular processes, including the metabolism of carbohydrates, terpenoids, and polyketides. The most enriched pathways were further analyzed in each category. Importantly, ultrasound upregulated three key genes namely the arahy. Tifrunner. gnm1.ann1.DXZI51, arahy.Tifrunner.gnm1.ann1.VGN2GE, and arahy.Tifrunner.gnm1.ann1.Y23DM6 that could have increased the content of resveratrol via phenylpropanoid biosynthesis. Furthermore, this study shows that B3, MYB transcription factor-like families play a significant role in response to ultrasound treatment. Overall, this study provides useful transcriptomics and proteomics information highlighting the molecular mechanisms that influence nutritional differences in peanut sprouts.

Effect of thiamethoxam seed treatment in peanut

AbstractTobacco thrips (Frankliniella fusca) and tomato spotted wilt (TSW) orthotospovirus (family Tospoviridae, genus Orthotospovirus) can reduce peanut (Arachis hypogaea L.) yield. Systemic insecticides are applied in the seed furrow at planting and to peanut foliage to reduce injury from tobacco thrips and decrease incidence of TSW. Research was conducted in Georgia, North Carolina, South Carolina, and Virginia in 2013 and 2014 to compare the effect of the following treatments on tobacco thrips feeding injury and expression of TSW in peanut: thiamethoxam seed treatment, thiamethoxam seed treatment followed by acephate 3 weeks after planting, phorate applied in the seed furrow at planting, and a nontreated check. Tobacco thrips feeding injury and TSW incidence were significantly higher in thiamethoxam and thiamethoxam followed by acephate‐treated peanut than peanut treated with phorate. Thiamethoxan seed treatment followed by acephate resulted in significantly lower tobacco thrips feeding injury compared to thiamethoxam seed treatment alone. Yield of Virginia market type cultivars was greater when thiamethoxam was followed by acephate applied to peanut foliage or when phorate was applied compared with nontreated peanut or the seed treatment alone. Runner market type cultivars yielded higher when phorate was applied compared with nontreated peanut while peanut treated with thiamethoxam with or with acephate yielded similar to both of these treatments.

Responses of tobacco thrips and peanut to imidacloprid and fluopyram

AbstractTobacco thrips (Frankliniella fusca Hinds) can reduce peanut (Arachis hypogaea L.) yield if not controlled in many instances in North Carolina and Virginia. Systemic insecticides are often applied in the seed furrow at planting to suppress tobacco thrips and protect peanut yield. Foliar sprays of acephate [N‐(methoxy[methylsulfanyl]phosphoryl)acetamide] are often made regardless of the insecticide applied at planting. Imidacloprid [(NE)‐N‐[1‐([6‐chloropyridin‐3‐yl]methyl)imidazolidin‐2‐ylidene)nitramide] plus fluopyram [N‐(2‐[3‐chloro‐5‐(trifluoromethyl)pyridin‐2‐yl]ethyl)‐2‐(trifluoromethyl)benzamide])] is registered for use in peanut but information in the peer‐reviewed literature is limited regarding its effectiveness in suppressing tobacco thrips and whether or not a foliar application of acephate is needed when this product is used. Peanut injury caused by tobacco thrips was lower when phorate [diethoxy‐(ethylsulfanylmethylsulfanyl)‐sulfanylidene‐λ5‐phosphane] or imidacloprid were applied alone compared with imidacloprid plus fluopyram in 16 trials conducted in North Carolina and Virginia from 2014 to 2020. However, all insecticides applied at planting protected peanut from injury caused by tobacco thrips well enough to prevent yield loss compared with nontreated peanut. Although acephate decreased visible injury caused by tobacco thrips, yield was not affected by acephate regardless of the systemic insecticide applied at planting. The results from these trials indicate that imidacloprid plus fluopyram offers adequate suppression of tobacco thrips to protect yield. Although acephate suppressed tobacco thrips, yield was not affected by acephate.

Sixty-One Years Following Registration, Phorate Applied In-Furrow at Planting Suppresses Development of Late Leaf Spot on Peanut.

Late and early leaf spot are caused by Nothopassalora personata and Passalora arachidicola, respectively, and are damaging diseases of peanut (Arachis hypogaea L.) capable of defoliation and yield loss. Management of these diseases is most effective through the integration of tactics that reduce starting inoculum and prevent infection. The insecticide phorate was first registered in 1959 and has been used in peanut production for decades in-furrow at planting to suppress thrips. Phorate further provides significant suppression of Tomato spotted wilt virus infection beyond suppression of its thrips vector alone by activating defense-related responses in the peanut plant. From six experiments conducted from 2017 to 2019 in Blackville, SC, Reddick, FL, and Quincy, FL, significantly less leaf spot defoliation was exhibited on peanuts treated with phorate in-furrow at planting (26%) compared with nontreated checks (48%). In-season fungicides were excluded from five of the experiments, whereas the 2018 Quincy, FL, experiment included eight applications on a 15-day interval. Across individual experiments, significant suppression of defoliation caused by late leaf spot was observed from 64 to 147 days after planting. Although more variable within location-years, pod yield following phorate treatment was overall significantly greater than for nontreated peanut (2,330 compared with 2,030 kg/ha; P = 0.0794). The consistent defoliation suppression potential was estimated to confer an average potential net economic yield savings of $90 to $120 per hectare under analogous leaf spot defoliation. To our knowledge, these are the first data in the 61 years since its registration demonstrating significant suppression of leaf spot on peanut following application of phorate in-furrow at planting. Results support phorate use in peanut as an effective and economical tactic to incorporate to manage late and early leaf spot infections and development of fungicide resistance.

Utilization of Imidacloprid to Control Thrips in Peanut in North Carolina

ABSTRACT Tobacco thrips (Frankliniella fusca Hinds) is an important pest in peanut (Arachis hypogaea L.) in North Carolina and injury from this insect can lower yield. Research was conducted from 2012 through 2014 in North Carolina to compare visible injury from tobacco thrips feeding and peanut yield when acephate, imidacloprid, and phorate were applied alone in the seed furrow at planting or followed by acephate applied postemergence 3 weeks after planting. In a second experiment conducted during the same time period, a commercial liquid formulation of Bradyrhizobia inoculant was applied alone or with imidacloprid in fields with and without plantings of peanut in recent years. Peanut injury from tobacco thrips feeding was reduced by acephate, imidacloprid, and phorate applied in the seed furrow at planting compared with non-treated peanut. Acephate applied 3 weeks after planting generally reduced injury from thrips. Pod yield was greater when imidacloprid was applied compared with yield for the non-treated control or when acephate was applied in the seed furrow. Pod yield was similar regardless of in-furrow treatment when acephate was applied postemergence. Thrips control by imidacloprid was not affected by Bradyrhizobia inoculant, and imidacloprid did not negatively affect efficacy of Bradyrhizobia inoculant regardless of previous field history. These data indicate that imidacloprid protects peanut as well as or more effectively than the systemic insecticides acephate and phorate and that imidacloprid is compatible with Bradyrhizobia inoculant.

Weed Control and Peanut (Arachis hypogaea L.) Response to Acetochlor Alone and in Combination with Various Herbicides

ABSTRACT Acetochlor, a chloroacetamide herbicide, is now registered for preplant (PPI), preemergence (PRE), and postemergence (POST) application in peanut. Field research was conducted during 2011 and 2012 in Georgia and North Carolina to determine peanut response and weed control by acetochlor compared with S-metolachlor alone and in programs with other herbicides. In weed-free experiments, peanut tolerance to acetochlor (1.26 and 2.52 kg ai/ha) and S-metolachlor (1.42 kg ai/ha) were evaluated when applied PPI, PRE, early postemergence (EPOST), or POST. Peanut tolerance to acetochlor was similar to S-metolachlor with no negative impact of either herbicide on peanut yield compared with non-treated peanut in absence of weed interference. When applied PRE, acetochlor controlled Palmer amaranth, pitted morningglory, sicklepod, and Texas millet similarly to S-metolachlor while control of broadleaf signalgrass was greater with S-metolachlor. Weed control programs containing EPOST and/or POST applications of herbicides following PRE herbicides provided the best overall weed control but did not affect yellow nutsedge control regardless of whether acetochlor or S-metolachlor were applied. Herbicide programs including PRE, EPOST, and POST herbicides most often resulted in the greatest yields. There was no difference in peanut yield regardless of the presence of acetochlor or S-metolachlor in a comprehensive herbicide program.

Peanut (Arachis hypogaea L.) Response to Carfentrazone-ethyl and Pyraflufen-ethyl Applied Close to Harvest

ABSTRACT Morningglory (Ipomoea spp.) and other weeds are often present at peanut harvest and can interfere with digging pods and inverting vines. Carfentrazone-ethyl and pyraflufen-ethyl control large morningglory and could be an effective strategy as harvest aids in peanut. However, crop response to these herbicides has not been determined for Virginia market type peanut cultivars in North Carolina. One experiment was conducted during 2012, 2013, and 2014 to determine peanut response to carfentrazone or pyraflufen-ethyl applied postemergence 1 and 2 weeks prior to digging peanut pods and inverting vines. In a second experiment conducted during 2014 and 2015, peanut response to carfentrazone-ethyl, diclosulam, pyraflufen-ethyl, lactofen, and 2,4-DB applied 4 wk before digging (WBD) was determined. Visible peanut injury from carfentrazone-ethyl and pyraflufen-ethyl did not exceed 40% regardless of application timing or rate, and peanut yield was not affected compared with non-treated peanut regardless of visible injury when applied 1 or 2 WBD. However, when applied 4 WBD, peanut yields were 9 to 10% lower when carfentrazone-ethyl or pyraflufen-ethyl were applied compared with non-treated peanut. Diclosulam, lactofen, and 2,4-DB did not adversely affect yield. These results show that carfentrazone-ethyl and pyraflufen-ethyl will not affect peanut yield within 2 WBD but can reduce yield when applied earlier in the season during pod fill.

RTK GPS and Automatic Steeringfor Peanut Digging

<abstract><title><italic>Abstract. </italic></title> Peanut harvesting is a two-stage process. In the first stage, a digger-shaker-inverter implement is used to plow peanut from the ground. In the second stage, a combine is used to thresh peanut pods from the vines. Yield loss can be significant, especially during the digging stage where the implement may not be properly aligned over the rows of peanut. In this study, RTK-based automatic steering was compared to manual steering to determine the potential for reduced yield losses. In addition, peanut response to the plant growth regulator prohexadione calcium was compared to a non-treated peanut to determine if reduced yield losses were obtainable. Prohexadione calcium regulator did not improve yield significantly. However, use of RTK based automatic steering was significant, increasing harvested yield by 510Â kg/ha or 11%.

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.

Weed Management in Peanut with Herbicide Combinations Containing Imazapic and Other Pesticides

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.

Influence of Application Variables on Peanut (Arachis hypogaea L.) Response to Prohexadione Calcium

Abstract Prohexadione calcium retards peanut vegetative vine growth, improves row visibility, and potentially reduces pod shed, thus increasing pod yield compared with non-treated peanut. Although prohexadione calcium has been registered for use in peanut for the past decade, practitioners continue to express a range of questions about use including banded application, compatibility with other agrichemcials, and interactions of application rate and timing. In experiments over multiple years, applying prohexadione calcium to lateral branches only of peanut increased row visibility compared with banded applications over main stems or broadcast applications over the entire peanut canopy. Similarly, when using different spray nozzle configurations, greater row visibility was noted when the highest rate of prohexadione calcium was applied over lateral branches compared with broadcast applications of a uniform rate across all spray nozzles or when the highest rate was delivered to main stems. Delaying the first of two sequential applications of prohexadione calcium 1 wk after 50% row closure resulted in reduced row visibility regardless of application rate when compared with sequential applications initiated at 50% row closure. Applying prohexadione calcium within 2 to 3 wks prior to digging and vine inversion resulted in minor increases in improved row visibility and did not affect pod yield. Efficacy of prohexadione calcium was not affected by tank mixing with pyraclostrobin or 2,4-DB.

Peanut (Arachis Hypogaea L.) Cultivar Response to Prohexadione Calcium

Abstract 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.

Physiological behavior of root-absorbed flumioxazin in peanut, ivyleaf morningglory (Ipomoea hederacea), and sicklepod (Senna obtusifolia)

Abstract Previous research has shown that flumioxazin has the potential to cause peanut injury. In response to this concern, laboratory and greenhouse experiments were conducted to investigate the influence of temperature on germination of flumioxazin-treated peanut seed and the effect of interval between flumioxazin application and irrigation on peanut emergence and injury. Laboratory experiments using 14C-flumioxazin were also conducted to investigate differential tolerance exhibited by peanut, ivyleaf morningglory, and sicklepod to flumioxazin. Flumioxazin treatments containing either water-dispersible granular or wettable powder formulation at 1.4 μmol L−1 did not influence germination compared with nontreated peanut across all temperature regimes (15 to 40 C). Peanut treated with either formulations of flumioxazin preemergence and receiving irrigation at emergence and 2 and 4 d after emergence were injured between 40 and 60%. Peanut treated at 8 and 12 d after emergence were injured between 25 and 15...

Peanut (Arachis hypogaea L.) Response to the Hormonal Plant Growth Regulator Early Harvest®

Abstract Experiments were conducted from 1996 through 2001 in Georgia, North Carolina, and Texas to determine peanut response to the commercial plant growth regulator Early Harvest® (a commercial mixture of cytokinin, gibberellic acid, and indole butyric acid). Early Harvest (applied in the seed furrow) or Early Harvest TST (applied as a dry seed treatment) followed by four foliar applications (four-leaf peanut, initial pegging, 14 d after initial pegging, and pod fill), was compared to non-treated peanut in five, 13, and three experiments in these respective states. Early Harvest did not affect pod yield or gross economic value of peanut regardless of location, cultivar, or edaphic and environmental conditions. These data suggest that a spray program consisting of Early Harvest most likely will not improve pod yield or gross economic value of peanut.

Peanut (Arachis hypogaea L.) Response to Cyclanilide and Prohexadione Calcium

Abstract Excessive growth of Virginia market-type peanut affects row visibility and pod yield of peanut. Ten experiments were conducted from 2000 to 2002 in North Carolina to compare peanut response to cyclanilide and prohexadione calcium applied at 50% row closure followed by a repeat application 2 wk later. Cyclanilide and prohexadione calcium increased row visibility in all experiments. Main stem height was shorter at the end of the season when cyclanilide and prohexadione calcium were applied compared with non-treated peanut in all experiments except one. Prohexadione calcium improved row visibility compared with cyclanilide in three experiments and equaled cyclanilide in seven experiments. Main stem height was similar following application of cyclanilide and prohexadione calcium in eight of the 10 experiments. When pooled over experiments, pod yield ranged from 4210 to 4480 kg/ha and did not differ between non-treated peanut and peanut treated with either plant growth regulator. However, prohexadione calcium did increase pod yield of peanut compared with cyclanilide. Results indicate that cyclanilide is not as effective as prohexadione calcium in managing peanut vine growth because of inconsistent enhancement of row visibility and possible negative impacts on pod yield.

Tolerance of Peanut (Arachis hypogaea L.) to Herbicides Applied Postemergence

Abstract Experiments were conducted from 1999 through 2001 in North Carolina to determine peanut response under weed-free conditions to applications of postemergence herbicides. In one set of experiments, peanut tolerance to acifluorfen plus bentazon or acifluorfen plus bentazon plus 2,4-DB applied alone or with diclosulam, dimethenamid, flumioxazin, or metolachlor 6 to 8 wk after peanut emergence was evaluated. In a second set of experiments, paraquat plus bentazon was applied alone or with diclosulam, dimethenamid, flumioxazin, imazethapyr, or metolachlor 2 wk after peanut emergence. In a third set of experiments, imazapic was applied alone or with diclosulam or flumioxazin 3 to 4 wk after peanut emergence. In the fourth experiment, 2,4-DB was applied approximately 7, 5, or 3 wk before digging and inversion of vines. Flumioxazin applied alone or with aciflurofen plus bentazon (with or without 2,4-DB) injured peanut more than diclosulam, dimethenamid, or metolachlor applied alone or with acifluorfen plus bentazon or aciflurofen plus bentazon plus 2,4-DB. Flumioxazin reduced pod yield 620 kg/ha when compared to non-treated peanut. Additionally, acifluorfen plus bentazon and acifluorfen plus bentazon plus 2,4-DB reduced yield by 200 and 150 kg/ha, respectively, when compared with non-treated peanut. Flumioxazin applied with paraquat plus bentazon was more injurious than diclosulam, dimethenamid, imazethapyr, or metolachlor applied with paraquat plus bentazon. There was no difference in peanut injury when paraquat plus bentazon was applied alone or with diclosulam. Dimethenamid or metolachlor increased injury by paraquat plus bentazon. Although diclosulam did not affect peanut injury from imazapic, injury increased when imazapic was applied with flumioxazin. When pooled over nine sites, 2,4-DB did not adversely affect pod yield, gross economic value, or percent seed germination when applied 7, 5, or 3 wk before vine inversion.

Influence of Prohexadione Calcium on Pod Yield and Pod Loss of Peanut

Excessive vegetative growth of peanut (Arachis hypogaea L.) can make digging and inverting operations less efficient. Reducing vine growth by applying a suitable plant growth regulator would be an efficient way to manage peanut vines. Pod yield, market grade factors, and gross economic value of peanut treated with prohexadione calcium (calcium salt of 3,5‐dioxo‐4 propionylcyclohexanecarboxylic acid) were evaluated at 19 sites in North Carolina during 1999 and 2000. Experiments were also conducted at two locations each during 1999 and 2000 to determine the effect of prohexadione Ca, digging date, and lifting (shaking peanut vines after digging to remove soil before combining) on combined yield, market grade factors, gross economic value, seed germination, and pod loss of the virginia market‐type cultivar NC 12C. Prohexadione Ca at 140 g a.i. ha−1, applied at 50% row closure and repeated 2 wk later, increased row visibility at harvest, pod yield by 310 kg ha−1, and gross economic value of quota peanut by $223 ha−1 when pooled over 19 sites. Prohexadione Ca increased combined yield by 220 kg ha−1 and decreased percent pod loss by 4% regardless of digging date and lifting treatment compared with nontreated peanut. Prohexadione Ca did not affect maximum yield (sum of pods remaining in soil and on the soil surface and pods that were combined) or germination of peanut seed. These data suggest that increased combined yield noted following application of prohexadione Ca can be partially attributed to decreased pod loss.

Peanut Response to Prohexadione Calcium in Three Seeding Rate–Row Pattern Planting Systems

Peanut (Arachis hypogaea L.) in the USA is generally grown in single rows spaced 91 to 102 cm apart. Research suggests that pod yield can be increased by growing peanut in twin rows (18–23 cm spacing) on beds spaced 91 to 102 cm apart. Prohexadione Ca (Ca salt of 3,5‐dioxo‐4‐propionylcyclohexanecarboxylic acid) increases row visibility and in some instances increases pod yield and improves market grade factors. Research was conducted to determine response of peanut grown in three seeding rate–row pattern planting systems (single rows at a seeding rate of 120 kg ha−1 or twin rows spaced 18 cm apart on beds spaced 91 cm apart at seeding rates of 145 and 190 kg ha−1) to prohexadione Ca applied at 50% row closure. Row visibility increased and main stem height was shorter at the end of the season when prohexadione Ca was applied in most environments and for most seeding rate–row pattern combinations when compared with nontreated peanut. Pod yield and gross economic value increased 160 kg ha−1 and $96 ha−1, respectively, when prohexadione Ca was applied irrespective of the seeding rate–row pattern combination or environment. Prohexadione Ca also increased the percentage of extra large kernels (% ELK) but did not affect percentages of sound mature kernels (SMK), other kernels (OK), sound splits (SS), or total sound mature kernels (TSMK). Seeding rate–row pattern combination affected pod yield, market grade, and gross economic value although a consistent trend was not apparent.

Alterations of Leaf Epicuticular Wax of Peanut (Arachis hypogaea) by Applications of Herbicides and Adjuvants1

Abstract Leaf surface morphology of untreated peanut leaves and peanut leaves treated with herbicides and adjuvants were examined using scanning electron microscopy. Electron micrographs revealed that the adaxial surface of untreated peanut leaves was covered with crystalline wax platelets above an amorphous layer of wax. Electron micrographs revealed that peanut leaves treated with acifluorfen plus nonionic surfactant, bentazon and lactofen with crop oil concentrate, and 2,4-DB, altered the leaf surface morphology when compared to nontreated peanut leaves. Alterations in the leaf epicuticular wax structures appeared amorphous-like rather than normal plate-like structures. Nonionic surfactant and crop oil concentrate applied alone to peanut leaves altered the epicuticular wax structures similarly to that of herbicides plus adjuvants.

Influence of Adjuvants on Peanut (Arachis hypogaea L.) Response to Prohexadione Calcium

Abstract Research has demonstrated that prohexadione calcium (calcium salt of 3,5-dioxo-4-propionylcyclohexanecarboxylic acid) retards vegetative growth of peanut (Arachis hypogaea L.) and in some cases increases pod yield, the percentage of extra large kernels, market value ($/kg), and gross value ($/ha). Spray adjuvants such as crop oil concentrate and nitrogen solution most likely will be recommended for application with prohexadione calcium. However, efficacy of prohexadione calcium applied with adjuvants has not been conclusively determined. Twelve experiments were conducted in North Carolina and Virginia during 1997 and 1998 to determine peanut response to prohexadione calcium applied with crop oil concentrate, urea ammonium nitrate, or a mixture of these adjuvants. Applying prohexadione calcium with urea ammonium nitrate, either alone or with crop oil concentrate, increased row visibility and shorter main stems compared with nontreated peanut or prohexadione calcium applied with crop oil concentrate. Prohexadione calcium increased pod yield, the percentage of extra large kernels, and gross value of peanut in seven of 12 experiments regardless of adjuvant when compared with nontreated peanut. Pod yield, the percentage of extra large kernels, and gross value of peanut were not affected in the other experiments. Prohexadione calcium did not affect the percentage of total sound mature kernels, the percentage of other kernels, or market value in any of the experiments regardless of adjuvant.