Extreme weather events such as tropical storms and hurricanes produce wind and water that can be detrimental to the yield and quality of flue-cured tobacco crops. This publication discusses the effects of wind and water damage on flue-cured tobacco; a research trial with delayed harvest intervals following Hurricane Irene in 2011; and considerations to help estimate the capacities of harvest and curing equipment after a tropical weather event.

Flooded or saturated soil conditions greatly reduce oxygen concentrations in the root zone. Such reduction or absence of oxygen causes leaves to wilt, making them more susceptible to sunscald if air temperatures become excessively hot in the days following a storm. Leaves may also begin to senesce (ripen) rapidly if oxygen is not replenished within the soil profile, and necrosis may occur at leaf tips. Standing water is a threat to plant health; however, this situation can be alleviated if drainage efforts are sufficient to promote water runoff or lateral flow once rainfall has ceased. Saturated soils (those at “field capacity”) are a more problematic issue because physical efforts to drain fields are often not sufficient to hasten drainage unless large drainage ditches exist. The installation of large ditches is not usually feasible in the immediate aftermath of a tropical storm or hurricane. It often takes two or three days for water to drain from the soil profile via gravitational flow, or percolation; drainage may take longer in soils with a high percentage of clay. Typically, if standing water does not drain sufficiently within 24 hours, root damage will occur, and if sufficient drainage does not occur within 48 hours, leaves are not likely to recover from wilting, and yield and quality will be severely compromised.

While waterlogged soils are of significant concern, wind sometimes results in greater damage to plants, as the type of injury associated with wind is twofold. The first type of injury is leaf drop, the physical detachment of a leaf or leaves from the stalk. The second type of injury is bruising, which results from cell destruction that causes water and chlorophyll (green pigment) to leak from the plant cell. Bruising ultimately causes leaves to turn brown or black and commonly results in very poor cured leaf quality, even when harvest immediately follows severe weather. Bruising is also commonly associated with a curing condition referred to as barn rot, which results in very poor leaf quality, value, and demand. Even if wind doesn’t cause considerable bruising, it may increase the rate at which a leaf ripens due to the natural presence of the plant growth hormone known as ethylene. The formation of ethylene is also promoted by other sources of leaf damage, including wilting and sunscald.

As remnants of hurricanes or tropical storms exit North Carolina, tobacco producers must consider the lasting effects to leaves that remain on the plant, on which visual injury is often largely absent. As previously noted, leaves that exhibit immediate bruising, discoloration, or physical damage following a storm event will more than likely result in a loss due to poor quality. The following information applies to commercial producers that did not experience crop loss after a hurricane.

Extensive research data that demonstrate the effects of extreme weather events on flue-cured tobacco are not available. However, we do have information from a “holding ability” study conducted in 2011 at the Border Belt Tobacco Research Station in Columbus County near Whiteville, NC. Holding ability, sometimes referred to as “holdability,” is the tobacco crop’s ability to maintain, or “hold,” a ripe condition without senescing. Holding ability usually only applies to upper stalk tobacco after the lower stalk has been harvested. The design of the trial included the comparison of multiple delayed harvest intervals. The dataset from this holding ability study provides a useful example of delaying tobacco harvest after a hurricane because plots were exposed to Hurricane Irene for a brief period (August 26 and 27 of 2011). Note that results represent the harvest of upper-stalk tobacco only (leaf and tip); the lug and cutter leaves had already been harvested when Hurricane Irene made landfall.

The yield, quality, price, and value of cured leaves were highest when tobacco was harvested two days after Hurricane Irene (Table 1), compared to three subsequent harvests at 10-day intervals. Wind and rain from Irene were not as extreme as that from other hurricanes (for example, Florence) in the Border Belt region of North Carolina (Table 3); therefore, leaf bruising and standing water were not as prevalent as expected within the first harvest interval. Following the first harvest, remaining plots were subsequently harvested every 10 days, which is the approximate duration of a complete curing cycle (filling the barn, curing the tobacco, bringing the tobacco into order [to an appropriate moisture level], and emptying the barn). In the second harvest interval (12 days after Irene), cured leaf yield began to decline due to leaf degradation, though not as rapidly as it did during the 22-day and 32-day harvest intervals (Table 1). Cured leaf quality, price, and value, however, were significantly reduced compared to the two-day harvest timing (Table 1). The reductions in quality and economic measurements were largely due to significant reductions in cured leaf quality that resulted from wind damage, which hastened the natural ripening process. Cured leaf measurements continued to decline as harvest was delayed by 22 days and were lowest in the 32-day harvest interval (Table 1).

Under normal growing conditions, yield, quality, price, and value measurements for upper-stalk positions are not likely to deteriorate as rapidly as those same measurements under hurricane conditions. The same holding ability trial was carried out at the same location in years without a hurricane; a subset of that data is reported in Table 2. Yield was highest when harvest occurred 13 days after ripe leaves were observed, with reductions being documented only at 23 and 33 days overripe. Of additional interest are the similarities between visual quality, price per pound, and per-acre value as harvest was delayed. The two varieties represented in Table 2 are K 326 and NC 196, popular varieties with excellent holding-ability characteristics.

Notes: Treatment means followed by the same letter within the same column are not significantly different at the α=0.05 level.

Results were pooled across the varieties PVH 2110, NC 196, GL 395, K 326, GF 318, CC 65, NC 299, NC 297, PVH 1452, and CC 35.

In addition to the statistical values presented in Table 1, cured leaf color is typically the primary determinant of flue-cured leaf quality. When harvest occurred two days after Hurricane Irene (Figure 1), leaf color was overwhelmingly dominated by ripe grades of tobacco (F and K color descriptions). When harvest occurred 12 days following Irene, greenish (V, immature) and nondescript (N, overripe to the point of damage) grades accounted for 10% of the color grade distribution, thus lowering both quality and price (Figure 1; Table 1). A further delay of harvest until 22 days after the storm system cleared increased N grades to 7.5% of the total and variegated, unripe grades (KV, variegated green, and KF, variegated orange) to 42.5% of the total (Figure 1). In addition, F and K grades were reduced to 42.5%, which is a decline of 47.5% and 57.5%, respectively, relative to the two previous harvest intervals. In the final harvest interval, N grades accounted for 92.5% of all grades received, with KV and K grades accounting for 5% and 2.5%, respectively. Ultimately, as harvest was delayed, leaf deterioration became more pronounced, with a large portion of leaves dying prior to harvest. Examples of accelerated leaf senescence from Hurricane Florence in 2018 are shown in Figure 2, and examples from Tropical Storm Debby in 2024 are shown in Figure 3 and Figure 4.

Notes: Treatment means followed by the same letter within the same column are not significantly different at the α=0.05 level.

Results are pooled across the varieties K 326 and NC 196.

In Whiteville, weather data from Hurricane Irene indicated 2.01 inches of rainfall and wind speeds less than 13 mph (Table 3). It is plausible that if rainfall totals and wind speeds had been higher, leaf-holding ability would have been reduced by comparison. Hurricane Florence in 2018 had stronger winds and higher rainfall at the same location, compared to Irene (Table 3).

^* Data provided by the North Carolina State Climate Office – North Carolina Climate Retrieval and Observations Network of the Southeast (CRONOS) Database. ↲

— = Data not available. ↲

Figure 1. Upper-stalk cured leaf color as affected by harvest delay after Hurricane Irene at Border Belt Tobacco Research Station. Data are pooled across 10 varieties and reflect average USDA color standards.

V, greenish (immature); KV, variegated green (unripe); KF, variegated orange (unripe); F, orange (ripe); K, variegated (ripe); N, Nondescript (oxidized/damaged).

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Figure 1. Upper-stalk cured leaf color as affected by harvest delay after Hurricane Irene at Border Belt Tobacco Research Station. Data are pooled across 10 varieties and reflect average USDA color standards.

V, greenish (immature); KV, variegated green (unripe); KF, variegated orange (unripe); F, orange (ripe); K, variegated (ripe); N, Nondescript (oxidized/damaged).

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Figure 2. Leaf response to Hurricane Florence over a three-day period: (a) Sept. 15, 2018 and (b) Sept. 18, 2018.

Photos courtesy of Norman Harrell, N.C. Cooperative Extension—Wilson County Center.

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Figure 2. Leaf response to Hurricane Florence over a three-day period: (a) Sept. 15, 2018 and (b) Sept. 18, 2018.

Photos courtesy of Norman Harrell, N.C. Cooperative Extension—Wilson County Center.

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Figure 3. Leaf response six days after the arrival of Tropical Storm Debby, Aug. 8, 2024, in two separate fields. Note that the yellow leaf color and wilting are present where water stood in fields.

Photos courtesy of Jared Butler, N.C. Cooperative Extension—Lee County Center.

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Figure 3. Leaf response six days after the arrival of Tropical Storm Debby, Aug. 8, 2024, in two separate fields. Note that the yellow leaf color and wilting are present where water stood in fields.

Photos courtesy of Jared Butler, N.C. Cooperative Extension—Lee County Center.

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Figure 4. Images of leaf response one day after (top photo) and six days after (bottom photo) the arrival of Tropical Storm Debby, Aug. 8, 2024. Note that the yellow leaf color and excessive wilting are present where water stood in the field

Photos courtesy of Connor Peacock, N.C. Cooperative Extension—Cumberland County Center.

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Figure 4. Images of leaf response one day after (top photo) and six days after (bottom photo) the arrival of Tropical Storm Debby, Aug. 8, 2024. Note that the yellow leaf color and excessive wilting are present where water stood in the field

Photos courtesy of Connor Peacock, N.C. Cooperative Extension—Cumberland County Center.

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Of additional consideration following a tropical weather event are curing capacity and the ability to harvest tobacco in a timely manner. The previously described research indicates the importance of quickly harvesting storm-damaged tobacco, but this is not always logistically possible. Unfortunately, field conditions may remain wet for a significant amount of time after storm events and limit access with any equipment. The following examples are provided as tools growers can use to estimate realistic harvest and curing capacities of their equipment, which may be of particular interest when managing a tobacco crop after a tropical weather event.

Flue-Cured Harvester Capacity

The effective field capacity (ac/hr) of a two-row self-propelled harvester depends on the field efficiency and average travel speed during operation. The working or material capacity (lb/hr) of the harvester will vary with field capacity and quantity of tobacco harvested for a given stalk position. Typically, three to four stalk positions are harvested per season. The weight and quantity of leaves harvested will be the lowest for lower-stalk tobacco and the highest for upper-stalk tobacco; as a result, the working capacity of the machine typically increases with stalk position harvested. The number of barns loaded per day could also fluctuate throughout the season due to weather conditions and agronomic factors. Assuming an average ground speed and field efficiency of 3 mph and 75%, respectively, the effective field capacity for a two-row self-propelled machine is approximately 2 acres per hour. Operating for 8 hours would result in harvesting about 16 acres per day. The working capacity (lb/hr) will increase as harvesting advances from lower-stalk to upper-stalk tobacco. As a result, the quantity of tobacco that could be harvested with a two-row machine in the same amount of time operated per day will increase. If growers use the Granville Equipment stripper harvester, as opposed to a conventional harvester, the effective field capacity will be almost double due to the significant increase in ground speed (5 to 6 mph). With the Granville Equipment harvester, the material capacity will also be greater due to the increased number of leaves that can be harvested. The number of barns loaded per day is typically not limited by the green leaf material handling equipment (such as field transport trailers, box loading systems, and conveyors) used by many growers. In addition, the working capacity of any harvesting equipment will vary with manufacturer, quality of maintenance performed, and age of equipment.

Bulk Curing Barn Capacity

There are many factors to consider when determining the number of barns required for a given acreage of flue-cured tobacco. The capacity of curing barns varies depending on the type and number of bulk containers used (racks or boxes). Many growers use curing barns that hold 8 to 10 bulk boxes. The assumptions in the following example are that a grower is using a 10-box capacity barn with Long manufacturing boxes (or similar size boxes) and that the seasonal average yield is 2,500 pounds of cured leaf per acre. Agronomic factors and weather can have a significant effect on the yield each season. The ratio of green leaf weight to cured leaf weight is approximately 6:1. The quantity of green tobacco loaded per box typically fluctuates during the harvest season from about 1,800 pounds to 2,200 pounds. Actual numbers may vary slightly from season to season. Assuming an average green weight loading rate of 20,000 pounds of green leaf per barn (2,000 pounds per box), the cured weight is about 3,330 pounds per barn. Based on an average yield of 2,500 pounds per acre and eight cures per barn during the season, the capacity is about 10.7 acres per barn. The barn field capacity increases if the grower plans to use the barns more than eight times per season but decreases if the yield per acre is greater than 2,500 pounds. Smaller-capacity barns, such as eight-box barns or rack barns, would result in fewer acres per barn for the same yield assumptions. Remember that the agronomic management factors and weather during the season can affect the capacity positively or negatively.

Collectively, our research indicates that tobacco should be harvested as soon as possible following a tropical weather event, particularly in the latter portion of the growing season when tobacco is more likely to be both mature (in stage and size) and ripe (in color). Growers likely have a harvest window of fewer than 10 days following a tropical system; after that period, deterioration will be substantial and leaf quality will be negatively impacted. Producers are strongly encouraged to consider harvest initiation and general crop recovery management on a field-by-field basis and to consult with North Carolina Cooperative Extension agents, if needed.