MILDEW TOLERANT
PUMPKIN VARIETY EVALUATIONS
IN PENNSYLVANIA

Timothy E. Elkner
Horticulture Extension Educator
Penn State Cooperative Extension
1383 Arcadia Rd., Rm. 1
Lancaster, PA 17601

Eric Oesterling
Horticulture Extension Educator
Penn State Cooperative Extension
RR 12, Box 202E, Donohoe Road
Greensburg, PA 15601

Lee Young
Horticulture Extension Educator
Penn State Cooperative Extension
100 West Beau Street, Suite 601
Washington, PA 15301

INTRODUCTION
Pumpkins are a very important crop in the mid-Atlantic region. In Pennsylvania, pumpkin acreage is second only to sweet corn. PA ranked first in fresh market pumpkin production in 2002 with 7,376 acres harvested for 9% of the total US acreage (non-processing). One of the major diseases limiting pumpkin yields is powdery mildew (PM). While there are fungicides available to control PM, it is still a problem for many growers. The purpose of this study was to evaluate PM tolerant and resistant pumpkin varieties under PA growing conditions.

MATERIALS AND METHODS
Seven varieties of small pumpkins (<5 lbs), 9 varieties of medium pumpkins (7-24 lbs.) and 7 varieties of large pumpkins (25+ lbs) were grown in Lancaster and Westmoreland counties in 2004. The pumpkins were grown using raised beds with black plastic row covers and drip irrigation. Spacing of the plants was as follows: small - 2 ft in row (Lancaster) or 2.5 ft (Westmoreland) X 8 ft between rows, medium - 4 ft in row X 8 ft between rows and large - 6 ft X 8 ft (Westmoreland), 5 ft X 9 ft (Lancaster). Transplants were set June 21 in Westmoreland and June 24 in Lancaster with the plants receiving a pre-plant drench of Admire. Recommended fertility, weed control and disease and insect control practices were used. There were two 10 plant replicates per variety at each location. Percent leaf surface and undersides infected with powdery mildew were rated on 10 plants per replicate on August 25 in Lancaster and September 3 in Westmoreland. Fruit were harvested and weighed on September 13 in Westmoreland and September 20 in Lancaster.

RESULTS AND DISCUSSION
Overall, at both locations, the large pumpkins had a greater percent PM leaf coverage than the medium and small pumpkins. The percent PM on the upper leaf surfaces was low this year probably because of the excessively wet season. However, there did appear to be a relationship between the percent PM coverage on the upper and lower leaf surfaces of each variety so relative susceptibility to PM can be estimated from the data.

Pumpkin varieties listed as mildew tolerant had as much (or more) powdery mildew coverage on their leaf surfaces as those without tolerance in the small varieties at both locations (Tables 1, 2). Varieties with mildew tolerance and resistance had less mildew in the medium and large pumpkin groups at Westmoreland and in the medium group at Lancaster. Aladdin had the lowest mildew coverage on the lower leaf surfaces at Lancaster but the highest coverage on the upper leaf surfaces. There did not seem to be a relationship between mildew tolerance/resistance and yield in our trials.

MSX 6075 was more productive and had larger fruit at Westmoreland than Lancaster, otherwise the data on size and yields for the small-fruited varieties were similar. The smaller pumpkins tended to have a smooth texture and good handles in quality evaluations at the Lancaster site. In the texture ratings a 1 is very smooth while a 5 has deep ribbing. In the handle ratings, 1 is poor (too small for fruit size, weak, etc.) while a 5 is large, dark green and strong. A good variety will have a rating of around 3 or better. Color on the medium and large pumpkins should be orange or dark orange. A yellow-orange fruit will not sell well when displayed with darker colored fruit.

Estimated yields were higher for both medium- and large-fruited varieties at the Westmoreland site. Estimated yield was calculated using yield/ft² in the experimental plots without allowing for spray/drive rows. I have no explanation for the higher yields at the western location. However, the top two yielding varieties were the same (RPX 1003, Gold Bullion) and Magic Lantern was third at Lancaster and fourth at Westmoreland. Gold Bullion was somewhat variable in size. Magic Lantern is the current 'standard' for medium-fruited pumpkins in eastern PA because of its dark-orange color and good handles. RPX-1003 had yellow-orange color and acceptable handles while Gold Bullion and Magic Lantern had good color and better handles. The MSX selections and Magician had good color and handles.

Golden Condor and Autumn King were the most productive large-fruited varieties at both locations. These varieties were similar in size and appearance. Aladdin was the third most productive variety at Westmoreland while it was fourth at Lancaster. Fruit quality on these top performers was similar with all having good color and handles.

Table 1: Yield and powdery mildew infection ratings for 23 varieties of small, medium, and large pumpkins grown in Lancaster County, PA in 2004. Click on variety name to view image.

**PMT = powdery mildew tolerant, PMR = powdery mildew resistant

Table 2: Yield and powdery mildew infection ratings for 23 varieties of small, medium, and large pumpkins grown in Westmoreland County, PA in 2004.

**PMT = powdery mildew tolerant, PMR = powdery mildew resistant

Table 3: Evaluation of color, shape, texture, and handle quality for 23 pumpkin varieties grown in Lancaster County, PA. Texture and handle quality are measured on a scale of 1-5 with 5 being the most desirable.