Loren R. Fisher

Cotton, Peanut, and Soybean Response to Sublethal Rates of Dicamba, Glufosinate, and 2,4-D

Abstract Development and utilization of dicamba-, glufosinate-, and 2,4-D-resistant crop cultivars will potentially have a significant influence on weed management in the southern United States. However, off-site movement to adjacent nontolerant crops and other plants is a concern in many areas of eastern North Carolina and other portions of the southeastern United States, especially where sensitive crops are grown. Cotton, peanut, and soybean are not resistant to these herbicides, will most likely be grown in proximity, and applicators will need to consider potential adverse effects on nonresistant crops when these herbicides are used. Research was conducted with rates of glufosinate, dicamba, and 2,4-D designed to simulate drift on cotton, peanut, and soybean to determine effects on yield and quality and to test correlations of visual estimates of percent injury with crop yield and a range of growth and quality parameters. Experiments were conducted in North Carolina near Lewiston-Woodville and Rocky Mount during 2009 and 2010. Cotton and peanut (Lewiston-Woodville and Rocky Mount) and soybean (two separate fields [Rocky Mount] during each year were treated with dicamba and the amine formulation of 2,4-D at 1/2, 1/8, 1/32, 1/128, and 1/512 the manufacturers suggested use rate of 280 g ai ha−1 and 540 g ai ha−1, respectively. Glufosinate was applied at rates equivalent to 1/2, 1/4, 1/8, 1/16, and 1/32 the manufacturers suggested use rate of 604 g ai ha−1. A wide range of visible injury was noted at both 1 and 2 wk after treatment (WAT) for all crops. Crop yield was reduced for most crops when herbicides were applied at the highest rate. Although correlations of injury 1 and 2 WAT with yield were significant (P ≤ 0.05), coefficients ranged from −0.25 to −0.50, −0.36 to −0.62, and −0.40 to −0.67 for injury 1 WAT vs. yield for cotton, peanut, and soybean, respectively. These respective crops had ranges of correlations of −0.17 to −0.43, −0.34 to −0.64, and −0.41 to −0.60 for injury 2 WAT. Results from these experiments will be used to emphasize the need for diligence in application of these herbicides in proximity to crops that are susceptible as well as the need to clean sprayers completely before spraying sensitive crops. Nomenclature:Dicamba; glufosinate; 2,4-D; cotton, Gossypium hirsutum L.; peanut, Arachis hypogaea L.; soybean, Glycine max (L.) Merr.Abstract Development and utilization of dicamba-, glufosinate-, and 2,4-D-resistant crop cultivars will potentially have a significant influence on weed management in the southern United States. However, off-site movement to adjacent nontolerant crops and other plants is a concern in many areas of eastern North Carolina and other portions of the southeastern United States, especially where sensitive crops are grown. Cotton, peanut, and soybean are not resistant to these herbicides, will most likely be grown in proximity, and applicators will need to consider potential adverse effects on nonresistant crops when these herbicides are used. Research was conducted with rates of glufosinate, dicamba, and 2,4-D designed to simulate drift on cotton, peanut, and soybean to determine effects on yield and quality and to test correlations of visual estimates of percent injury with crop yield and a range of growth and quality parameters. Experiments were conducted in North Carolina near Lewiston-Woodville and Rocky Mo...

Yield and Physiological Response of Flue-Cured Tobacco to Simulated Glyphosate Drift

Field trials were conducted in 2001 at the Tobacco Research Station near Oxford, NC, and in 2002 at the Lower Coastal Plains Research Station near Kinston, NC, to determine tobacco yield, injury, and shikimic acid accumulation in response to simulated glyphosate drift. Glyphosate was applied to 12- to 13-cm-high tobacco ‘K326’ early postemergence at 0, 9, 18, 35, 70, 140, 280, 560, and 1,120 (1×) g ai/ha. Crop injury was rated 7 and 35 d after treatment (DAT) and shikimic acid accumulation in leaves at 7 DAT, tobacco yield, and leaf grade index (whole-plant index of harvest interval leaf value) were also assessed. Shikimic acid accumulation and injury symptoms increased similarly as glyphosate rate increased. Glyphosate rates of 140 g/ha (0.125 of recommended rate) or higher resulted in significant crop injury, reduced tobacco yield, and decreased leaf grade index. Shikimic acid accumulation at 7 DAT was inversely related to tobacco yield. Shikimic acid accumulation was found to be an effective diagnostic tool to determine glyphosate drift in tobacco; however, in-season data are needed to correlate shikimic acid accumulation with yield loss. Nomenclature: Glyphosate; tobacco, Nicotiana tabacum L. ‘K326’. Additional index words: Crop injury, herbicide assay, shikimate. Abbreviation: DAT, days after treatment.

Uptake, translocation, and metabolism of sulfentrazone in peanut, prickly sida (Sida spinosa), and pitted morningglory (Ipomoea lacunosa)

Abstract Studies were conducted to evaluate uptake, translocation, and metabolism of root-absorbed 14C-sulfentrazone in peanut, prickly sida, and pitted morningglory. Peanut absorbed more than five and three times greater 14C-sulfentrazone than pitted morningglory and prickly sida, respectively. All plant species translocated appreciable amounts (≥ 39%) of radioactivity to the leaves. The three plant species had some capacity to metabolize 14C-sulfentrazone. At 3 h after treatment, 7, 29, and 71% of the radioactivity in the shoots of peanut, prickly sida, and pitted morningglory, respectively, was sulfentrazone. Sulfentrazone levels in the shoots at 3 and 6 h after treatment correspond to reported tolerance levels, with peanut being the most tolerant of the three species, whereas prickly sida and pitted morningglory are moderately tolerant and completely susceptible to sulfentrazone, respectively. Levels of metabolites varied among species, plant part, and harvest timing. On the basis of these data, tolerance in peanut is largely due to its ability to rapidly metabolize sulfentrazone. Nomenclature: Sulfentrazone; pitted morningglory, Ipomoea lacunosa L. IPOLA; prickly sida, Sida spinosa L. SIDSP; peanut, Arachis hypogaea L. ARAHY ‘NC 12C’.

EFFECT OF SULFENTRAZONE RATE AND APPLICATION METHOD ON WEED CONTROL AND STUNTING IN FLUE-CURED TOBACCO

Abstract Research was conducted at five locations in 1998 and three locations in 1999 to evaluate the effects of labeled and below-label rates of sulfentrazone on weed control and phytotoxicity in ...

MANAGEMENT OF AXILLARY SHOOT GROWTH AND MALEIC HYDRAZIDE RESIDUES WITH DIFLUFENZOPYR IN FLUE-CURED TOBACCO (NICOTIANA TABACUM)

Abstract Maleic hydrazide (MH) controls axillary shoot (sucker) growth in tobacco and is used on more than 90% of the tobacco acreage in North Carolina. Residues of MH on flue-cured tobacco often exceed residue limits set by foreign purchasers of U.S. leaf. Research was conducted at the Central Crop Research Station (CCRS) near Clayton, NC and the Border Belt Tobacco Research Station (BBTRS) near Whiteville, NC in 2003 and 2004 to evaluate diflufenzopyr, (2-(1-[([3,5-difluorophenylamino] carbonyl)-hydrazono}ethyl)-3-pyridinecarboxylic acid) (BAS 654 H and BASF 131) for the control of sucker growth. Diflufenzopyr was evaluated alone and in tank mixtures with the registered rate of flumetralin, and registered and reduced rates of MH. Treatments were arranged in a factorial design with MH at four rates (0, 0.6, 1.3, and 2.5 kg ai ha−1), flumetralin at two rates (0 and 0.7 kg ai ha−1), and diflufenzopyr at two rates (0 and 0.017 kg ai ha−1). All treatments were applied approximately ten days after the removal...

Tobacco Response to Residual and In-Season Treatments of CGA-3626221

Experiments were conducted to determine tobacco tolerance to CGA-362622 applied pretransplant (PRE-T) and postemergence (POST) to tobacco and applied the previous year preemergence (PRE) and POST to cotton. CGA-362622 applied at 3.75 or 7.5 g ai/ha PRE-T injured ‘K326’ flue-cured tobacco 1%, whereas POST treatments resulted in 4 to 5% injury. Tobacco injury was transient with no mid- or late-season injury noted. Tobacco yields from all CGA-362622 POST treatments were not different from the nontreated weed-free check. Tobacco treated with 7.5 g/ha CGA-362622 PRE-T yielded greater than nontreated weed-free tobacco or tobacco treated with CGA-362622 POST. When grown in rotation, tobacco was not injured, and yields were not influenced by CGA-362622 applied PRE or POST to cotton the previous year. Nomenclature: CGA-362622; cotton, Gossypium hirsutum L.; tobacco, Nicotiana tabacum L. Additional index words: Carryover, crop injury, sulfonylurea herbicide. Abbreviations: ALS, acetolactate synthase; LAYBY, late POST-directed; POST, postemergence; PPI, preplant incorporated; PRE, preemergence; PRE-T, pretransplant.

EFFECTS OF STAND LOSS, PLANTING DATE, AND REPLANTING METHOD ON YIELD AND QUALITY OF FLUE-CURED TOBACCO

Abstract Research was conducted at one location in 2003 and two locations in 2004 and 2005 to evaluate the effects of stand loss, planting date, and replanting method on flue-cured tobacco yield and quality. Stand loss treatments included a 10%, 20%, 30%, and 40% stand loss at two and four weeks after transplanting (WAT). In recent years, early season infections by Tomato spotted wilt virus (TSWV) have caused significant stand losses in North Carolina, so an additional treatment was included to simulate the effects of plant loss to tomato spotted wilt. Simulated losses consisted of a 10%, 10%, and 20% stand loss at 3, 4, and 5 weeks after transplanting, respectively. Planting date treatments included planting at the normal transplanting date and at 2, 3, 4, and 5 weeks after the normal transplanting date. To evaluate the effects of replanting method, tobacco was replanted at 2 or 4 weeks after normal replanting on an existing row ridge, a rebedded row ridge, and a tilled and rebedded row ridge. Due to exc...

INFLUENCE OF NITROGEN APPLICATION RATE ON THE YIELD, QUALITY, AND CHEMICAL COMPONENTS OF FLUE-CURED TOBACCO, PART II: APPLICATION METHOD

Research was conducted in 2012 and 2013 to determine the effect of nitrogen application timing and method on the yield, quality, and leaf chemistry of flue-cured tobacco. Liquid urea–ammonium–nitrate supplied 100% of the total nitrogen and was applied in differing combinations of rates, timings, and methods. Nitrogen rates above, at, and below recommendation for specific locations were split into two, three, or four application timings depending on treatment. Nitrogen application was initiated at transplanting and concluded before or at topping. Applications of nitrogen were either soil applied at each interval or were soil applied until topping where application occurred over top to promote stalk rundown. Leaf tissue samples were collected at layby and topping to evaluate total nitrogen content throughout the growing season. Composite cured leaf tissue samples from all four stalk positions were analyzed for total alkaloid and reducing-sugar content. Yield data were collected and leaf quality was determin...

Influence of Cultural Practices and Crop Rotation on Kenaf Yield in North Carolina

Kenaf is a relatively new crop to North Carolina and its impact on cropping systems has not been clearly determined. The impacts of crop rotation on kenaf, as well as the impacts of kenaf on rotation crops were examined. Crops preceding kenaf included corn, soybean, cotton, and peanut while crops following kenaf or corn included corn, soybean, cotton, peanut, and tobacco. Experiments were also conducted to define interactions among kenaf planting dates, row width/plant population systems, and cultivars. In one of two years, kenaf yield was lower when kenaf followed peanut or soybean compared to following cotton. Peanut and soybean yield were similar when following either corn and kenaf. However, corn and cotton yield was lower in one of two years when following corn compared to kenaf. Tobacco yield was similar when planted following either corn or kenaf. The interaction of planting date, row width/plant population, and cultivar was not significant for kenaf yield. No yield differences were observed between kenaf cultivars Everglade 41 and Tainung 2. Kenaf yield was higher when planted May 15 rather than June 15 and when kenaf was planted in rows spaced 8 inches apart (total plant population of 261,000 plants per acre) compared to rows spaced 36 inches apart (total plant population of 174,000 plants per acre).

NITROGEN APPLICATION RATE INFLUENCE ON YIELD, QUALITY, AND CHEMICAL CONSTITUENTS OF FLUE-CURED TOBACCO, PART I: APPLICATION TIMING

Research was conducted at 5 locations between 2012 and 2013 to determine the effect of nitrogen application rate and timing on yield, quality, and leaf chemistry of flue-cured tobacco. Urea–ammoniu...