‘Orange Bulldog’, A Virus-resistant Pumpkin for Fall Production in the Southeast

in HortScience
View More View Less
  • 1 Department of Horticulture, University of Georgia, East Georgia Extension Center, P.O. Box 8112, GSU, Statesboro, GA 30460
  • 2 Department of Horticulture, University of Georgia, 4604 Research Way, Tifton, GA 31793
  • 3 Vidalia Onion & Vegetable Research Center, 8163 Highway 178, Lyons, GA 30436
  • 4 Attapulgus Research & Education Center, P.O. Box 189, Attapulgus, GA 39815

Most ornamental pumpkins produced in the United States are Cucurbita pepo L., which are highly susceptible to virus and mildew diseases. ‘Orange Bulldog’ is a C. maxima Dutch. pumpkin developed with greater virus disease (Potyvirus group) resistance and tolerance for powdery mildew [Podosphaera xanthii (Castag.) U. Braun and N. Shish. (formerly known as Sphaerotheca fuliginea) or Golovinomyces cichoracearum (D.C.) Huleta (formerly known as Erysiphe cichoracearum)] and downy mildew [Pseudoperonospora cubensis (Berk. & M.A. Curtis) Rostovzev]. Germplasm from this species is known to be a source of multiple disease resistance, particularly to virus diseases (Keinath and DuBose, 2000; Paris and Brown, 2005). This variety was specifically developed for fall production in the Southeast as an ornamental pumpkin for fall and Halloween displays. This pumpkin should have a good fit for both roadside pick-your-own operations and wholesale growers for local markets. The fruit is edible and can be prepared like summer squash when immature or can be made into a suitable pumpkin filling when mature.

Origin

In 1996, seed of both oblong and flattened fruit of C. maxima were collected from natives in remote areas of Brazil by Krewer and interplanted in 1997. Putative hybrids from this planting were then planted in 1998 and became the basis for developing a pumpkin variety suitable for production in the Southeast. Individual fruit from the initial planting were used as the basis for developing populations in minimum isolation (plots were isolated by 9.1 m of planted muskmelon). Criteria for selection were for generally round fruit with an open cavity suitable for Halloween carving and capable of standing on the blossom end without support. Bright orange color was also an important criterion for selection. Continued recurrent phenotypic selection occurred until the winter of 2002–2003 at which time selections were grown in the greenhouse and selfed. Seed from these selfs were then used for 2 more years of recurrent phenotypic selection in 2003 and 2004. The final selection was made in 2004 when 13 open-pollinated fruit from two different locations (Attapulgus Research Farm, Attapulgus, GA, and the Vidalia Onion and Vegetable Research Center, Lyons, GA) were bulked as breeder seed and designated NP-04-1768. Foundation seed production, which produced ≈159 kg of seed, was done at the Vidalia Onion and Vegetable Research Center, Lyons, GA, in the spring of 2005.

Description

‘Orange Bulldog’ is a vining plant exhibiting vigorous growth with vines extending 3 to 4.5 m from the crown. Leaves are large reniform to orbiculate in shape without the serrated leaf margin common to C. pepo pumpkins. The leaf laminae are attached by long petioles allowing the leaves to be held up to 0.5 m above the ground near the crown. It produces yellow flowers. Fruits are round, mostly oblate to orbiculate, with pronounced furrows. They are bright yellow when immature, turning a light salmon to burnt orange color at maturity (Fig. 1). Fruit have an open cavity suitable for carving with a rind ≈4 cm in thickness. Immature fruit can be harvested and consumed like summer squash. Mature fruit can be processed for pie fillings. Fruit size ranges from 3 to 7 kg at maturity. The fruit has a pronounced yellow ground spot.

Fig. 1.
Fig. 1.

Examples of ‘Bulldog’ fruit, which show the variability in the fruit as well as the distinctive ground spot that is visible on some.

Citation: HortScience horts 42, 6; 10.21273/HORTSCI.42.6.1484

In the summer and fall of 2005, replicated trials were conducted at the Attapulgus Research Farm to evaluate NP-04-1768, which has been named ‘Orange Bulldog’. The trials consisted of eight entries in the summer and seven in the fall in randomized complete-block design experiments of four replications. Each experimental unit consisted of 10 plants with 3.7 m between-row and 1.8 m in-row spacing. The summer trial was transplanted with 2-week-old transplants on 19 May 2005 and harvested on 5 and 19 Aug. 2005. The fall trial had a similar arrangement and was transplanted on 18 July 2005 with harvest on 7 Oct. 2005. Cultural practices followed University of Georgia Cooperative Extension Service recommendations (Kelley and Langton, 2001). Both yield and number of fruit were transformed with square root (x) before analysis and the results were back-transformed to their original units to normalize the distributions (StataCorp, 2003). In addition, randomly selected leaf samples from each experimental unit from both trials were collected ≈2 weeks before harvest and sent to Agdia Inc. (Elkhart, IN) for virus screening with their cucurbit screen, which tested for 11 specific viruses as well as the Potyvirus group test. Finally, visual observations of overall plant condition were evaluated, which was based on disease incidence primarily incited by downy and powdery mildews. In addition, a visual rating of virus symptoms was also done. Analyses of visual ratings involved transforming the data with square root (x + 0.5) to normalize the distribution before analysis with results back-transformed to their original units (StataCorp, 2003). The enzyme-linked immunosorbent assay (ELISA) test data were transformed with square root (x) before analysis and back-transformed to their original units.

‘Orange Bulldog’ yielded significantly higher than other pumpkins in the summer and fall trials (Tables 1 and 2). In previous trials in 2003 and 2004, advance breeding lines similar to ‘Orange Bulldog’ had yields similar to commercial pumpkins in summer trials (data not shown) but consistently produced higher yields during fall trials. Low yields in both of these trials with conventional pumpkins (C. pepo) was primarily the result of severe viral infections, particularly if the plants were infected early, before flowering, in some cases resulting in little or no yield.

Table 1.

Pumpkin variety trial, Attapulgus Research and Education Center, Summer 2005.z

Table 1.
Table 2.

Pumpkin variety trial, Attapulgus Research and Education Center, Fall 2005.z

Table 2.

Visual foliar fungal disease (powdery and downy mildew) evaluations showed that ‘Orange Bulldog’ consistently had less disease than commercial cultivars (Tables 1 and 2). The visual evaluation of virus disease symptoms showed no difference in the disease ratings between the cultivars in the spring trial (Table 1), but the ratings were significantly lower in ‘Orange Bulldog’ in the fall trial (Table 2). Of the 11 viruses and Potyvirus group screened for by ELISA, only the Potyvirus group screen had any positives in the summer trial. The Potyvirus ELISA absorbance readings were significantly lower for ‘Orange Bulldog’ compared with the commercial cultivars except for ‘Longface’ and ‘Trickster’. In the fall trial, there were positive results for both the Potyvirus screen and Papaya Ringspot Virus (PRSV) with ‘Orange Bulldog’ having significantly lower absorbance readings for both the Potyvirus group screen and PRSV compared with the commercial cultivars.

‘Orange Bulldog’ consistently produces fruit during fall production, whereas commercial pumpkin cultivars often succumb to severe virus infections before fruiting. In addition, the ‘Orange Bulldog’ vines hold up well and should be particularly advantageous for pick-your-own marketers where vine cover is important, particularly for “reseeding” with additional fruit for continued sales.

Availability

Small quantities of seed are available from the senior author (GEB) to those willing to sign a nonpropagation agreement with the University of Georgia. Application for plant variety protection is currently underway with the hope that a commercial seed supplier will handle this cultivar.

Literature Cited

  • Keinath, A.P. & DuBose, V.B. 2000 Evaluation of pumpkin cultivars for powdery and downy mildew resistance, virus tolerance, and yield HortScience 35 281 285

    • Search Google Scholar
    • Export Citation
  • Kelley W.T., Langton J. & D.B. 2001 Commercial production and management of pumpkins and gourds Univ. of Ga. Coop. Ext. Serv. Bul. 1180

    • Export Citation
  • Paris, H.S. & Brown, R.N. 2005 The genes of pumpkin and squash HortScience 40 1620 1630

  • StataCorp 2003 Stata Statistical Software: Release 8.0 Stata Corporation College Station, TX

    • Export Citation

If the inline PDF is not rendering correctly, you can download the PDF file here.

Contributor Notes

Associate Professor, Extension Horticulturist–Vegetables.

Professor, Extension Horticulturist–Small Fruits.

Professor emeritus.

Farm Superintendent.

To whom reprint requests should be addressed; e-mail gboyhan@uga.edu.

  • View in gallery

    Examples of ‘Bulldog’ fruit, which show the variability in the fruit as well as the distinctive ground spot that is visible on some.

  • Keinath, A.P. & DuBose, V.B. 2000 Evaluation of pumpkin cultivars for powdery and downy mildew resistance, virus tolerance, and yield HortScience 35 281 285

    • Search Google Scholar
    • Export Citation
  • Kelley W.T., Langton J. & D.B. 2001 Commercial production and management of pumpkins and gourds Univ. of Ga. Coop. Ext. Serv. Bul. 1180

    • Export Citation
  • Paris, H.S. & Brown, R.N. 2005 The genes of pumpkin and squash HortScience 40 1620 1630

  • StataCorp 2003 Stata Statistical Software: Release 8.0 Stata Corporation College Station, TX

    • Export Citation
All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 186 64 2
PDF Downloads 56 28 0