Managing black shank disease in tobacco remains a critical challenge for growers, especially in areas with a history of the disease. To help identify the most effective fungicide programs, a trial was conducted in a commercial tobacco field in Johnston County, NC in 2024.The study was conducted using a randomized complete block design with four replications to ensure reliable results. Each plot measured 14.7 feet wide and 50 feet long, containing four rows of tobacco, with the two center rows used for evaluation.

The previous crop was sweet potatoes, and standard practices for non-irrigated tobacco production in North Carolina were followed. The tobacco variety NC196 was transplanted on April 15 at a 44-inch row spacing and 22-inch in-row spacing using a mechanical transplanter. This trial tested ten fungicide treatments against an untreated control (Table 1). Application methods varied by treatment to evaluate different strategies for black shank control.

Table 1. Fungicides evaluated for black shank suppression in Johnston County, NC, 2024 with ‘NC196’

Fungicide applications were made using a CO₂-pressurized backpack sprayer, calibrated to apply 15 gallons per acre at 30 PSI in a soil-directed band spray. To monitor disease progression, black shank incidence was recorded weekly from April 22 to July 10. Disease severity was calculated using the Area Under the Disease Progress Curve (AUDPC), a method commonly used to evaluate plant disease over time. The middle two rows of each plot were used for final yield evaluations. Harvesting was conducted in three stages based on stalk positions: lower stalk ( July 30), middle stalk (August 15), and upper stalk (August 29).

 The 2024 season began with an early-season drought but later experienced hurricanes and heavy rains. Black shank pressure was moderate to high throughout the season. Treatments with transplant-applied Orondis Gold Premix and Orondis Gold DC initially showed higher levels of chemical injury. However, all affected plots fully recovered within 40 days after treatment. All fungicide treatments significantly reduced black shank severity compared to the untreated control (Figure 1). The best-performing treatments included transplant-applied Orondis Gold Premix or Orondis Gold DC, followed by Ridomil Gold 480 SL and Presidio 4 SC. These treatments resulted in significantly higher yields than the untreated control, demonstrating their effectiveness for black shank management (Table 2). These results provide valuable insights for managing black shank with a combination of transplant-applied, in-season, and layby fungicide applications. While Orondis Gold Premix and Orondis Gold DC treatments showed some early phytotoxicity, plants recovered, and these treatments provided strong disease control and yield benefits.

Figure 1.Effect of fungicides on black shank severity in Johnston County, NC, 2024.

Table 2. Effect of fungicides on yield in Johnston County, NC, 2024.

With black shank pressure varying season to season, continued trials are necessary to further refine fungicide programs and ensure that growers have access to data-driven disease management strategies.