Jack-o’-lantern pumpkin (Cucurbita pepo ssp. pepo) is an economically important crop grown for fall decoration in the United States, and they are traditionally carved and illuminated for display during the holiday of Halloween. In 2014, over 20,000 ha of pumpkins were planted in the United States, with a farm value of $145 million. The state of New York is one of the highest ranked states in value of production each year, often first in the nation. In 2014, the total farm value of the pumpkin crop in New York was $20.5 million, making jack-o’-lantern pumpkins a significant source of income for farmers (U.S. Dept. of Agriculture (USDA), National Agricultural Statistics Service, 2016). Because the crop has such high value, significant effort is put into controlling diseases that could decrease the value of the crop.
Powdery mildew, caused by Podosphaera xanthii and Erysiphe cichoracearum, is one of the major diseases that reduce the yield of susceptible pumpkins (McGrath and Thomas, 1996; Pérez-García et al., 2009). The pathogen is an obligate biotroph (Green et al., 2002) which overwinters in the southern United States on alternate hosts and on greenhouse-grown cucurbits. The pathogen is spread each year by airborne conidia, generally from the southern United States, where cucurbits are grown early in the season, to the northern United States. The disease is easily recognized by its white colonies that appear on the leaves of plants before spreading to the petioles and stems. Older leaves on mature plants are often infected first. Plants that have maturing fruit and plants grown in high-density plots are favorable for the pathogen (McGrath, 2011). Infection can cause the leaves to wither and senesce, which often leads to the death of the plant. This regularly results in shriveled and weakened peduncles (“handles” of the jack-o’-lanterns), reducing the marketability of the pumpkins (Zitter et al., 1996). Because of these factors, resistance to powdery mildew is an important trait for jack-o’-lantern pumpkins. The powdery mildew–resistant (PMR) pumpkin inbred lines we describe herein (Fig. 1) are the original source of powdery mildew resistance in many commercially available pumpkins. This study evaluates and compares the field performance characteristics of these PMR pumpkin inbred lines to commercially available cultivars (Table 1). Considered characteristics include yield, growth habit, size, maturity, and powdery mildew resistance.
Seed sources, pedigrees, and generation of the PMR pumpkin lines and cultivars in the trial.
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