Keeping it green: Gaining 60 pounds a day

The squash bug, when feeding, can inject bacteria that cucurbit yellow vine decline. The two center bugs are mature adults while the two to the left are immature (5th instar nymphal stage).

One of the most popular sessions at the annual Mid Atlantic Fruit and Vegetable Conference (MAFVC) is on pumpkins. Not hard to see why as it is grown on hundreds of Pennsylvania farms, over several thousand acres, and having a crop value of over $13 million. In fact, the production of orange globes places Pennsylvania in the top 5 across the US (data from USDA, National Agricultural Services’ Census of Agriculture and Quick Stats).

Ironically, it is one of our local vegetables that is not consumed on a great scale. The majority of Pennsylvania pumpkins are for the decorative market (contrast that to the leading production state, Illinois, where the majority of their pumpkins are for edible purposes).

With that in mind, the pumpkin session at the 2019 MAFVC included a speaker that addressed this ornamental topic. The invited speaker was Tim Parks, to talk about the science and art of growing giant pumpkins. And what gives Parks the authority to give out advice? He knows his stuff as he grows monsters that need a crane system to determine the weight. But he is also neck deep in organizing contests for the growing sport of giant pumpkin growing. Because of his passion and efforts, he was inducted into the Giant Pumpkin Growers Hall of Fame in 2006.

During the course of his presentation, there were some eye-popping ideas. Ordinary pumpkin seed won’t cut it in this competition. The genetics has to be closely followed and only the top-of-the line seed should be planted. He mentioned that one giant pumpkin seed can cost $1500. If shooting for a record, it is a worthwhile investment (a grower won $6000 in New Hampshire last year for the new US record).

Pumpkins of this size are heavy scavengers, for both water and nutrients, in order to bulk up. In fact, he likes to see pumpkins gaining 50-60 pounds per day in peak season. The pumpkin weight benchmarks for Parks are 1,000 pounds by August 1, another 1,200 pounds by September 1, and finish up with 200-300 pounds by October 1.

PHOTOS PROVIDED Tim Parks stands amongst his giant pumpkins at a competition.

Parks also talked the importance of dealing with pest issues to achieve optimal pumpkin growth. Insect and disease activity can stress the plant and reduce photosynthesis, all resulting in low pumpkin weights. This was a nice transition into the next couple of speakers.

Dr. Gerald Brust, IPM Vegetable Specialist at the University of Maryland, gave an overview of some insects commonly found in pumpkin production. Time was spent on a new invasive disease vectored by squash bugs. The bacteria that causes cucurbit yellow vine decline is passed from the squash bugs’ needle-like mouth parts into the plants vascular system when feeding. The bacteria can multiply in the plants ‘plumbing system’ causing the leaves to develop a bright yellow color and eventual death.

Penn State’s Vegetable Plant Pathology Specialist, Dr. Beth Gugino, delved deeper into disease issues by talking about crop management in wet years. Pretty timely presentation in that parts of Pennsylvania experienced summer rains that set records this past growing season. After listening to the litany of organisms that thrive in wet weather, it is amazing that pumpkin crops ever get to the finish line.

One key point in her presentation dealt with soil health. Incorporating cover or green manure crops should occur every year. Not only will it improve drainage, but it can build up beneficial soil organisms to help manage some disease-causing organisms. She also mentioned the use of plastic mulch, which can create a barrier between the pumpkin and soil, lessening some fruit rots.

Even then, fungicide programs are a must in order to have pumpkins for the front porch. Plenty of products are available that can give good control but she stressed that these products have limits. Because they are so site specific on the disease organism, resistance can easily develop. To maintain efficacy, products should be rotated every application. Dr. Gugino stated that in a wet year, spray applications might be applied more frequently.

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Tom Butzler is a horticulture educator with the Pennsylvania State University Cooperative Extension Service and may be reached at

570-726-0022.

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