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 manufacturer's suggested use rate of 280 g ai ha−1and 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 manufacturer's 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.

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.

Core Ideas Lower‐leaf removal will reduce cured leaf yield but can reduce the portion of lower‐demand stalk positionsNitrogen application after leaf removal is of limited value and is currently discouragedIf these programs are to find commercial success, a higher selling price should be offered by leaf purchasers With a current global over‐supply of flue‐cured tobacco (Nicotiana tabacum L.), tobacco producers in North Carolina have been encouraged to remove the lowermost leaves prior to harvest due to their low value in manufactured products. The objective of this research was to compare lower‐leaf removal programs. Research was conducted in 2016 and 2017 to quantify the agronomic effects of three lower‐leaf removal programs (0, 4, and 8 leaves plant−1) and the subsequent delivery of four N application rates (0, 5.6, 11.2, and 16.9 kg N ha−1 above base recommendation). All treatments combinations were applied during the early flowering stage of growth (8–10 wk after transplanting), when plants were approximately 120 cm tall. Programs absent of leaf removal generally produced the highest cured leaf yield. The addition of 16.9 kg N ha−1 increased yield when compared to lower N application rates within the 4‐leaf removal program. Nitrogen application did not affect yield in the 8‐leaf removal program. Cured leaf value was greatest in the 0‐leaf removal program (USD $10,131 ha−1) and was reduced in the 4‐ and 8‐leaf programs by $1611 and $2645 ha−1, respectively. Lower‐stalk positions were nearly eliminated in the 8‐leaf removal program, while the 4‐leaf removal program reduced their presence by more than 50%. Ultimately, if these programs are to be encouraged or required by industry, the removal of four leaves per plant proved to be more practical when paired with additional N, due to moderate yield reduction and lower‐stalk leaf production.

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-ammonium-nitrate was applied at 75, 100, and 125% of the recommended nitrogen rate for each specific field condition. All treatments were applied at differing intervals beginning at transplanting and concluding prior to or at topping. Yield data were collected postharvest, and leaf quality was determined according to U.S. Department of Agriculture grade. Crop value per hectare was quantified by a combination of yield and quality. Tissue samples were collected at layby and topping to evaluate total leaf nitrogen content at the respective growth stages. In addition, SPAD meter readings were collected at topping. Composite cured leaf tissue samples from all 4 stalk positions were analyzed for total alkaloid and reducing-sugar content. Data were subjected to analysis of variance (ANOVA) with the use of the PROC GLM procedure in SAS ver. 9.4. Treatment means were separated with the use of Fisher's protected LSD at P # 0.05. Crop yield, quality, and value were not affected by treatments across all locations, thus leading to the conclusion that all nitrogen application rates and timings were suitable under the observed growing conditions. Leaf nitrogen content at layby and topping, total alkaloids, reducing sugars, and SPAD readings were affected by application rate and timing. In general, as rate of applied nitrogen increased, alkaloid levels increased and reducing sugars decreased. Leaf nitrogen content at topping and SPAD measurements were highest in plots receiving a nitrogen application later in the season. Excessive rainfall in both seasons likely played a significant role in observed results. Based on current knowledge and information gained from this research, lateseason nitrogen application is a useable tool but should be performed with caution to prevent reduction in leaf quality.

Core Ideas Poultry feather meal is acceptable in organic flue‐cured tobacco production. Application rates of organic N should reflect those in conventional production. Soil moisture is critical for N mineralization and assimilation. Information on N management in organic flue‐cured tobacco production is limited. Research was conducted from 2012–2013 to determine the effects of two certified organic N sources applied at three rates on the yield, quality, and chemical constituents of flue‐cured tobacco. These organic N sources included Nature Safe 13–0–0 (NS) and Nutrimax 12–1–0 (NM), both of which consisted of hydrolyzed poultry feather meal. Application rates for both fertilizer sources were 17 kg N ha−1 above recommendation (B+), at recommendation (B), and 17 kg N ha−1 below recommendation (B–). A conventional control containing urea‐ammonium‐nitrate (UAN) was applied at the B application rate. Tobacco yield and quality were similar among conventional and organic N programs. Leaf N concentration, SPAD measurements at flowering, and total alkaloid concentration of cured leaves responded positively to increased N application rates, regardless of organic fertilizer source. The largest increases in nitrogenous‐based leaf constituents were observed in this study where B+ treatments were applied; however, those increases did not translate into increased leaf yield or quality and could delay the initiation of leaf senescence in growing seasons with low soil moisture. Results from this study demonstrate the acceptability of poultry feather meal sources for organic tobacco production, and confirm that application rates of organic N sources should follow conventional recommendations.