Tomato spotted wilt virus (TSWV) is an economically important plant virus, belonging to the family Bunyaviridae and genus Tospovirus, first identified in the United States in the middle to late 1980s and in North Carolina tobacco in 1988. By 1997 TSWV had been identified in nearly every North Carolina county. TSWV incidence has increased since its introduction. Tobacco plants infected with TSWV display a range of symptoms, including wilting and yellowing of leaves, ring spots, necrotic lesions, discoloration of leaf veins, and stunting. The majority of tobacco plants infected with TSWV will eventually die. TSWV is transmitted mechanically by 7 thrips species worldwide. The tobacco thrips, Frankliniella fusca (Hinds) (Thysanoptera: Thripidae) is the most important vector of TSWV in eastern and central North Carolina, and the western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) is a locally important vector in the western piedmont and mountainous region of the state. Previous studies have revealed differences in disease progression between burley and flue-cured types of tobacco for some soil-borne diseases, such as black shank and Granville wilt. However, little is known about the differences in TSWV susceptibility between these two types of tobacco. In these field studies TSWV infection rates in burley and flue-cured tobacco were compared side by side under several conditions. Results of the study indicated that burley tobacco is more susceptible to TSWV.

Crop performance trials are conducted in nearly every state as part of the land-grant mission. These trials have been conducted for flue-cured tobacco in the southeastern United States since 1954 and continue today. Even though the trials are conducted in a scientific manner, they are subject to variability caused by management and natural causes like diseases and insects. This article looks at the variability of 3 measurements from the North Carolina Official Flue-Cured Tobacco Variety Trials from 1981 through 2001. Yield, grade index, and dollar value per hectare ($/ha) were examined with the use of a procedure developed for other crops. First the relationship between error and mean was established. For these 3 traits there were no relationships between error and mean. A pooled (average) variance was calculated and then a maximum allowable variance was determined by multiplying the pooled variance by 2. Six out of 112 environments had questionable accuracy for yield; there were 7 questionable environments for grade index, and there were 6 for $/ha. Five questionable environments were common between yield and $/ha and 1 other $/ha environment had high error for yield. Grade index had only 1 common questionable environment with yield and none with $/ha. It is advocated that those who run crop performance trials examine their data for accuracy before publication and choose an alpha level between 0.20 and 0.40 to avoid Type II errors.

The tobacco budworm, Helicoverpa armigera, is a devastating pest of tobacco in Malawi. Experience has shown that by the time this pest is noticed, considerable damage has already been done to tobacco during the early stages of infestation. There is a need to manage future infestations correctly by combining safe and effective measures that can provide early control and detection of the pest. In recent years, the number of conventional pesticides for budworm control on tobacco has declined, and their use has increasingly become undesirable due to the buildup of resistance, concerns with pesticide residues, and environmental pollution. This has created an urgent need to diversify strategies to manage pests sustainably. One effort in this direction has been to evaluate effective and safer alternative insecticides that are compatible with integrated pest management (IPM). Experiments were conducted from 2011 to 2014 to evaluate the efficacy of 2 new insecticides, Prevathon® 5 SC, and Cyazypry 20 SC, with the aim of finding effective and safer alternatives for control of the tobacco budworm. A total of 10 treatments were evaluated in randomized complete blocks and levels of budworm infestation were evaluated in each treatment at 2, 4, and 6 wk after planting. The results indicated that Prevathon® 5 SC applied at transplanting (40 ml/10 L, 30 ml/plant) followed by a spray (14 ml/10 L water) at 4 weeks after transplanting provided effective budworm control (2.5% infestation) compared to about 20.9% infestation in untreated checks at Mwimba and 5.2% vs. 48.7% at Kandiya Research Station, respectively. Cyazypyr 20 SC applied at transplanting (10 ml/10 L, 30 ml/plant) followed by a spray (3.4 ml/10 L water) at 4 weeks after transplanting provided effective budworm control: 5.6% against 20.9% at Mwimba and 8.2% against 48.7% in the untreated at Kandiya Research Station, respectively. Prevathon® 5 SC and Cyazypyr 20 SC are promising alternatives for budworm control because they will provide the needed early insect pest protection compared with the currently recommended insecticides which are applied after pest damage is noticed.

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, late-season nitrogen application is a useable tool but should be performed with caution to prevent reduction in leaf quality.

Forty-two years of daily temperature and dew point data (1959–2000) for Lexington, KY, along with the yearly crop grade percentages from burley sales data, were used to determine the effects of temperature and relative humidity on crop quality during the curing process. Crop quality was defined by the yearly burley grade index and the yearly burley sales percentages for 3 leaf color groups: tan, red, and green. The daily weather data were used to form hourly temperature and relative humidity profiles for each day during each curing season. The curing environment was defined by degree hour sums that were determined for various temperature, relative humidity, and temperature–relative humidity variables. Statistical correlations were performed between the environmental variables and the various crop quality measures to establish what curing conditions were favorable or less favorable for grade index and the color groups. These correlations were evaluated for 14 exposure times beginning at 2 days into the cure and ending with 28 days. The environmental variables shown in this study had significant correlations for a good portion of the 28-day curing period. Generally it was found that environmental conditions favorable for one leaf color were often detrimental to another. One example of this is that larger amounts of degree hours in the 18.3–23.9°C range (65–75°F) were found to be very beneficial for producing red leaf color while also tending to prevent the development of leaves with green color. The correlations also showed that an increase in relative humidity hours in the 70–75% humidity range was beneficial in the development of leaves with red color and that higher humidity (above 75%) may still benefit leaf coloration in this group.

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 determined according to U.S. Department of Agriculture grade. Crop value per hectare was determined using a combination of yield and quality. Data were subjected to analysis of variance using the PROC GLM procedure in SAS ver. 9.4. Treatment means were separated using Fisher's Protected LSD at P ≤ 0.05. Soil-applied treatments yielded higher than stalk rundown treatments but contained lower nitrogen content at topping and chlorophyl level (SPAD) measurements. Leaf quality was similar when nitrogen was applied as a stalk rundown at above recommended rates and when soil applied at recommended rates. Leaf value and total alkaloid content were not affected by treatments; however, sugar content was highest when less nitrogen was applied early in the season. Leaf nitrogen was higher at layby when a larger percentage of nitrogen was applied earlier in the season. Rainfall played a significant role in observed results and producers should exercise similar treatments with caution.