Due to its geographical location, North Carolina is subject to encounter tropical weather during August through October annually, similarly to other southeastern coastal states. Furthermore, the large majority of cotton is produced in the coastal plains region of NC, which in general, is lower in elevation and nearer the coastline in a state that interfaces the ocean more easterly than neighboring states. This exposure increases the likelihood of the predominate cotton production regions of NC encountering both substantial wind speeds and flooding from tropical events that impact the eastern seaboard. Significant yield loss has been observed during previous tropical events over the past several years. Additionally, anecdotal observations suggests that yield loss is greater when tropical events occur during late September and October versus when they occur during late August or early September. Furthermore, in some cases, varieties touted to be “stormproof” appear to result in lower yield losses versus the more open varieties when tropical events occur. However, yield losses as related to wind speed are often unpredictable, and as such, the value of stormproof varieties in these weather events is also difficult to quantify, necessitating research into this matter.
The objectives of this research were to quantify the effects of known tropical wind speeds on both stormproof and non-stormproof varieties, to determine and quantify the effects of stormproof characteristics on yield loss of cotton subjected to tropical winds and to quantify yield losses due to exposure of cotton to various tropical wind speeds.
Research was conducted at the Upper Coastal Plains Research Station in Rocky Mount, NC during 2023. Cotton was planted on April 12, 2023 to improve the probability of reaching maturity so that defoliation and all treatments could be implemented in time to showcase this trial at the NC Cotton Field Day on September 14, 2023. Treatments included two varieties: PHY 400 W3FE, which is touted to be stormproof, and thus more resilient to weathering, and DP 2127 B3XF, which is known to be showy and loose in the burr, and thus less resilient to weathering. Plots consisted of 2 rows, each planted to one of the aforementioned varieties, and were 10 ft in length. Additional treatments included two simulated tropical wind speeds: 30-40 mph, which is the lowest wind speed thought to impact cotton yields and more likely to occur on the edges of a tropical system, and 60-70 mph, which is more likely to be encountered when a hurricane directly hits our cotton production region. Both wind speeds were implemented using standard commercial leaf blowers calibrated using a handheld Kestrel 3000 wind meter. Wind speeds were held constant by using the throttle position brakes on the leaf blowers and conducted in oscillating motion for 5 min. simultaneously on each side of the plot. Prior to implementation of wind treatment, all plants within each plot were completed saturated with water using a gas-powered pressure washer. Lastly, all of the aforementioned treatments were applied to cotton at 15-20 percent open bolls (prior to defoliation), or at 90-100 percent open bolls (2 weeks post defoliation). Yield losses were computed as percent of exposed (open) bolls lost, to normalize between maturity differences (rate of boll opening) between the two varieties, as well as estimated yield loss in lbs/A. Estimated yield loss was computed using the standardized rule of 12 bolls per ft of row (on 36-inch rows) equating to one 500-lb bale per acre. Assuming an average of 4 locks per boll, this would equate to 48 locks per ft of row equating to one 500-bale per acre yield. The number of missing locks were counted in each 10-ft plot, both before and after wind treatments to determine the number of locks lost due to wind treatment. Data were subjected to analysis of variance and means were separated using the LSD test at p < 0.05. [READ MORE]