Date Available


Year of Publication


Degree Name

Master of Science in Biosystems and Agricultural Engineering (MSBiosyAgE)

Document Type

Master's Thesis




Biosystems and Agricultural Engineering

First Advisor

Dr. Timothy Stombaugh


Traditionally, burley tobacco has been harvested by hand because the green plant weight, volume, and leaf fragility make mechanical harvesting very challenging. This study examined possible ways to wilt a plant still standing in the field (termed ‘pre-wilting’) to reduce weight, volume, and leaf fragility. Several methods of pre-wilting burley tobacco plants in the field were explored including: root pruning, stalk girdling, freezing with liquid nitrogen, and burning. Experiments were conducted in three locations over three consecutive years during the tobacco harvest season. Leaf breaking angle, leaf moisture content and time-lapse photography were investigated as methods to quantify treatment effects on wilting. The time-lapse photography helped reveal that wilting was most prevalent during the late afternoon, and that wilted plants sometimes began to recover after more than five days, apparently due to root re-growth. Root pruning was the only mechanical means that caused witling reliably during the first two years of testing, and even then the results were somewhat inconsistent. During the third year, a high-clearance tobacco sprayer was modified with a hydraulically actuated coulter disc in order to root-prune a large number of subjects.

Digital Object Identifier (DOI)

Tobacco_Prewilting_Sawzall_Root_Prune.mp4 (12629 kB)
Video 3-1 - Using the variables from table 5-6, a prediction was graphed (Figure 5 16)

Tobacco_Prewilting_Alternative_Methods.mp4 (21391 kB)
Video 3-2 - Timelapse video: yellow flag - MAPP gas on stalk, orange - liquid nitrogen poured on plant, blue - liquid nitrogen poured on stalk

Tobacco_Prewilting_2-Sided_Prune_at_4_5_3_and_1_5_inches.mp4 (25590 kB)
Video 3-3 - Timelapse video of 2-sided root pruning: yellow flag - 4.5" cut, orange - 3" cut, blue - 1.5" cut, white - burnt

Tobacco_Prewilting_Full_Scale_Test.mp4 (28871 kB)
Video 4-1 - Timelapse video of all phase two treatments, Plot B, phase two

Tobacco_Prewilting_Liquid_Nitrogen_Cup_Test.mp4 (28456 kB)
Video 4-2 - Timelapse video of nitrogen treated plants, Plot C, phase two

Drive.mp4 (7637 kB)
Video 5-1 - Demonstration of normal operation, root-pruning one side of a row

Coulter_Root_Prune.mp4 (12700 kB)
Video 5-2 - Timelapse video: treated plants, cut-width between 4 and 5 inches