Optimizing organic fertility management for virus-resistant ‘Orange Bulldog’ pumpkin production in the southeast

Commodities

Practices

Pumpkin production in Georgia is limited due to high disease and pest pressure, which reduces yield and discourages adoption of this crop by farmers (Coolong et al. 2023). Organic pumpkin production is further constrained by the lack of researched-based organic fertility guidance. A recently available cultivar 'Orange Bulldog' (Cucurbita maxima) offers improved resistance to powdery mildew, downy mildew, and potyviruses, making it a promising option for organic production (Boyhan et al. 2007). However, optimal organic nitrogen management strategies for pumpkins under Georgia conditions are not well defined.

The goal of this project is to evaluate the effects of organic nitrogen application rates on the productivity and plant health of 'Orange Bulldog' pumpkins and develop regionally appropriate fertility recommendations. The project addresses three objectives: (1) quantify the effects of five organic N rates on yield, fruit size, and marketability; (2) evaluate relationships between nitrogen availability and disease incidence and severity; and (3) develop and disseminate recommended organic nitrogen application ranges for pumpkins.

Field trials will be conducted over two growing seasons using a randomized complete block design with five nitrogen treatments and four replications. Data collection will include weekly disease/pest assessments, soil nutrient monitoring, and evaluations of yield and fruit quality.

Expected outcomes include improved nitrogen use efficiency, reduced production uncertainty, and region-specific fertility recommendations that support profitable, environmentally sound organic pumpkin production in Georgia. Results will be disseminated through peer-reviewed publication and extension materials for growers.

The long-term goal of this project is to improve organic fertility management for vegetable production in Georgia by optimizing nitrogen fertility for disease-resistant pumpkin production. To achieve this goal, the project will pursue the following objectives:

Objective 1: Evaluate the impact of five organic nitrogen treatments on pumpkin yield, fruit size, and marketability of the cultivar 'Orange Bulldog' under Georgia field conditions over two growing seasons.

Objective 2: Evaluate the relationship between nitrogen availability and disease incidence and severity (specifically powdery mildew, downy mildew, and potyvirus symptoms) through weekly field assessments and determine how nitrogen management influences crop and soil health.

Objective 3: Develop and disseminate a regionally appropriate recommended range for organic nitrogen applications that maximize yield and fruit quality while minimizing excess nutrient inputs and associated environmental risks.