Skip to Main Content

The University of Tennessee Institute of Agriculture
vegetable production

Frequently Used Tools:


2009 Pumpkin Powdery Mildew Resistance Variety Trial in Tennessee

Annette Wszelaki, Craig Canaday, Randi Dunagan


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?

• Applied 50 lbs N, 50 lbs P2O5, and 150 lbs K2O pre-plant

• Planted 22 varieties from seed June 12, 2009

• Four replications per variety

• Row spacing 9’ between rows, 5’ between hills, 4 hills/plot, 4 plants/hill, thinned to 2 plants/hill

• Side dressed with 30 lbs N when vines began to run

• Irrigated 3 times to supplement natural rainfall

• Pest control: Weeds: Ethalfuralin preemergence Glyphosate and paraquat used in alley ways postemergence Insects: Scouted regularly Rotated carbaryl, esfenvalerate and bifenthrin for control of cucumber beetles, squash bugs and squash vine borers Diseases: Scouted regularly Alternated chlorothalonil and myclobutinil for control of powdery and downy mildew

• Harvested September 23, 2009

• Washed pumpkins for storage in 100 ppm bleach solution

• 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) ⇒ Storability (duration)

What did we find?

Yield The top yielders by weight were Camaro and HSR 4721, an experimental variety from Hollar Seeds (since named Corvette). Camaro yielded an average of 22.7 tons/acre with 75% marketable fruit and an average fruit weight of 16.7 pounds. HSR 4721 (Corvette) yielded 21.7 tons/acre with 76% marketable fruit and an average fruit weight of 10.2 pounds. These two varieties also showed the least powdery mildew at harvest. The top yielder by number was also HSR4721 (Corvette). This variety averaged over 4,417 fruit per acre. While the top yielder by number, the yield was decreased by nearly 50% compared to last year. Rounding out the top five for marketable yield were Merlin (Harris), Spartan (Seedway) and ACX 7301 (Abbott & Cobb). Superior and Howden had the highest percentage of unmarketable fruit– both at 60%. ACX 7302, Pankow’s Field and Howden were the lowest yielding varieties in the trial. Both Pankow’s Field and Howden are known to be susceptible to powdery mildew and were used in the trial as controls.


Pumpkin yield and powdery mildew severity at harvest for 22 varieties of jack o’ lanterns.

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. Percent unmarketable was based on fruit number.


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). In these 22 varieties, color ranged from light to medium orange. HSR 4721 (Corvette) was the lightest pumpkin in the group, while Spartan was the darkest. Shape ranged from round to slightly oblong. Howden, ACX 6501 and HSR 4721 (Corvette) tended to be variable in shape, ranging from 5 to 8, 3 to 9 and 3 to 6, respectively. Suturing ranged from none (ACX 6501, HSR 4710 and Warlock) to medium (Magic Wand). Stem length ranged from medium to medium-long. Stem thickness ranged from medium to medium-thick. Attachment ranged from slightly below average to above average.


Subjective ratings of color, shape, suturing, and stem length, thickness and attachment for 22 varieties of jack o’ lanterns.

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


Length and Width For length and width measurements, HSR 4710 (since named Mustang) measured both the longest and widest, followed closely by Warlock, Camaro, Gladiator and Spartan. Charisma and HSR 4721 (Corvette) were the smallest in length, while Howden and Pankow’s Field were the smallest in width.

Storage Eight pumpkins (4 washed/4 unwashed) were placed into storage on September 23. These pumpkins will be weighed every two weeks until the end of October to document weigh loss and overall storage-life.

Conclusions Heavy disease pressure reduced pumpkin yield and quality, Camaro was the top yielder by weight, while HSR 4721 (Corvette) yielded the most pumpkins per acre and came in second for yield by weight. Both of these varieties also ranked highest for powdery mildew resistance, which reinforces variety selection as the first line of defense in an integrated disease management program.

Acknowledgements Thank you to Bob Hayes, Jason Reeves, the Madison County Master Gardeners and the WTREC Farm Crew for an enormous amount of help with plot planting, maintenance and harvest, and to Abbott and Cobb, Harris, 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.




To download a pdf, click here.