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2008 Pumpkin Powdery Mildew Resistance Variety Trial

Annette Wszelaki and Craig Canaday


To evaluate powdery mildew resistance, yield, and fruit and stem characteristics, as well as postharvest storability of experimental and commercially available jack o' lanterns for production in Tennessee.

What did we do?

  • Broadcast and disked in 50 lb N, 50 lb P2O5, and 150 lb K2O pre-plant
  • Planted 22 varieties from seed June 3, 2008
  • Four replications per variety
  • Row spacing 9’ between rows, 5’ between hills, 4 hills/plot, 4 plants/hill thinned to 2 plants/hill
  • Irrigated 15 times to supplement natural rainfall
  • Pest control:
    • Weeds: Curbit preemergence Poast postemergence Gramoxone used in alley ways postemergence
    • Insects: Scouted regularly Rotated Sevin, Asana and Capture for control of cucumber beetles, squash bugs and squash vine borers
    • Diseases: Scouted regularly One spray of Bravo and one spray of Quadris
  • Harvested September 10, 2008
  • Washed half of the pumpkins for storage in 100 ppm bleach solution/half unwashed
  • Stored on concrete floor in shed
  • Traits evaluated:
    • Total yield (tons/acre)
    • Marketable yield (tons/acre)
    • Number of fruit per acre
    • Average weight per pumpkin (pounds)
    • Length (inches)
    • Width (inches)
    • Color (yellow to deep orange)
    • Shape (flat to oblong)
    • Suturing (none to deep)
    • Stem thickness (thin to thick)
    • Stem length (short to long)
    • Stem attachment (poor to excellent)
    • Powdery mildew on stem (none to severe)
    • Storability (duration)

What did we find?

Yield The top yielder by weight was an experimental variety from Hollar Seeds called HSR4710. It yielded an average of 43.8 tons/acre with 95% marketable fruit and an average fruit size of 15 pounds. The top yielder by number was also an experimental variety from Hollar called HSR4721 (since named Corvette). This variety averaged over 8,000 fruit per acre with 98% marketable fruit and an average weight of 8 pounds per pumpkin. Rounding out the top five are Camaro (Hollar), Spartan (Seedway) and Magic Wand (Harris Moran). Charisma, Magic Lantern and 20 Karat Gold had the highest percentage of unmarketable fruit.- all over 20% Pankow’s Field and Howden were two of the lowest yielding varieties in the trial. Both are susceptible to powdery mildew.


Yields per acre were scaled up from 9' x 20' plots with 4 hills/plot and hill spacing of 5' within the row. 2 plants/hill.


Subjective Ratings Pumpkin color, shape and suturing, as well as stem length, thickness and attachment were rated subjectively at harvest on a 1-9 scale (see below for scale key). Stem powdery mildew was rated on a 1-5 scale (see below). In these 22 varieties, color ranged from light to deep orange. Shape ranged from round to slightly oblong. Suturing ranged from none to deep. Stem length ranged from medium to long. Stem thickness ranged from thin-medium to medium-thick. Attachment ranged from slightly below average to above average. Stem powdery mildew ranged from approximately 10% to nearly 80% at harvest.


Color Scale: 1=Yellow, 5=Orange, 9=Deep Orange Shape Scale: 1=Flat, 5=Round, 9=Oblong Suturing Scale: 1=None, 5=Medium, 9=Deep Stem Length Scale: 1=Short, 5=Medium, 9=Long Stem Thickness Scale: 1=Thin, 5=Medium, 9=Thick Stem Attachment Scale: 1=Poor, 5=Average, 9=Excellent Stem Powdery Mildew Scale: 1=1%, 2=10%, 3=30%, 4=60%, 5=100%


Length and Width For length and width measurements, King Midas measured both the longest and widest, followed closely by Spartan and HSR 4710 (since named Mustang). Capital measured the smallest.


Conclusions There are many powdery mildew resistant jack-o’-lantern varieties that perform well in Tennessee under a reduced spray program, which deliver on pounds per acre as well as number of fruit per acre. Camaro, Spartan and Magic Wand were three of the top yielding commercially available varieties and all show high resistance to powdery mildew. Washing the pumpkins in a 10% bleach solution did not improve storability, and there were no differences in keeping quality between the varieties studied here.

Acknowledgements Thank you to Bob Hayes, Jason Reeves and Randi Dunagan and the WTREC Farm Crew for an enormous amount of help with plot planting, maintenance and harvest, and to Abbott and Cobb, Harris Moran, Hollar Seeds, Johnny’s Selected Seed, Outstanding Seed, Seedway, and Siegers for the donation of seed for this trial.


Copyright © 1999 by The University of Tennessee. All rights reserved.

This research represents one season's data and does not constitute recommendations.  After sufficient data is collected over the appropriate number of seasons, final recommendations will be made through research and extension publications.




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