Pumpkin patch: Wet soils may be haven for disease

COLUMBUS – Bad timing of rain showers is slowing pumpkin development and may pose disease problems for growers later in the season.

Mac Riedel, an Ohio State University Extension vegetable pathologist, said that rain showers the end of spring delayed planting and cool June temperatures slowed plant development.

So far, so good. “Everything looks good so far. The plants are just smaller and we are a bit behind schedule in fruit set,” Riedel said. “Right now plants are just beginning to flower. This same time last year, fruit had already set.”

Growers should be gearing up for potential disease development. Recent heavy rains, causing saturated soils and localized flooding, is setting the stage for a variety of diseases.

Already present? In fact, said Riedel, anthracnose – a fungal disease spurred on by wet conditions in the spring – is already present in some pumpkin fields.

“We’ve started our spray program about two weeks earlier than normal because of anthracnose,” Riedel said. “The spray program usually coincides with the development of powdery mildew the end of July or early August.

“If growers don’t get a handle on anthracnose now it’s going to set in the fruit and affect fruit quality.”

Other diseases. Growers should also be keeping an eye on other fungal diseases like powdery mildew, downy mildew and the little-known Microdochium blight.

“The soils are fairly wet now. It wouldn’t take much to get those diseases rolling,” Riedel said. “Conditions like this are perfect for Microdochium blight, but we haven’t seen any of it so far.”

Ruined patch. Researchers continue to evaluate the disease, which is spurred on by warm weather and wet conditions and can infect the entire pumpkin plant making it virtually unable to sell.

Preliminary lab research has revealed that Microdochium blight can reproduce on a wide variety of weeds, including dandelion, and it has also been found on spring “volunteer” pumpkins – pumpkins generated from leftover seeds.

Weedy disease? “We are running additional lab studies and we are also determining whether or not the disease is found naturally on weeds in the field,” Riedel said.

“The feasibility of it developing early in the season is a concern. It would mean growers would have to start their spray programs six weeks to a month earlier and increase the number of sprays, which would increase the cost.”

According to the USDA, Ohio is ranked fifth in the nation in pumpkin production.

Approximately 5,000 to 6,000 acres of pumpkins are grown in Ohio, generating roughly $25 million a year in revenue in local sales and exports to southern states.

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Pumpkin Field Day set for Aug. 11

SOUTH CHARLESTON, Ohio – Growing great pumpkins will be the focus of a Pumpkin Field Day Aug. 11, 4-6 p.m., at the Western Branch of the Ohio Agricultural Research and Development Center.

The branch is located on state Route 41, between Interstate 70 and the town of South Charleston.

The event is sponsored Ohio State University Extension and its Vegetable Crops Team.

The branch has more than eight acres of research devoted to pumpkins, said Jim Jasinski, a researcher with Ohio State University Extension’s Integrated Pest Management Program and one of the organizers of the event.

Highlighted work. He will be joined by Ohio State researchers Bob Precheur, Mac Riedel, Celeste Welty and Andy Wyenandt who will highlight their work on:

* Pumpkin variety trials.

* Fungicide spray programs.

* Giant pumpkin production.

* “Chemigation” of pumpkins for cucumber beetle control.

* Bacterial wilt variety trial.

* Use of herbicide and mulches for weed and disease control.

In addition to the production-oriented topics, Rob Leeds, agriculture agent for Ohio State University Extension in Delaware County, will lead a discussion concerning insurance issues related to ag entertainment, Jasinski said.

The point will be brought home with a demonstration of a pumpkin catapult.

During a wagon tour of the plots, growers will be encouraged to walk around and ask questions of the specialists.

Both Pesticide Applicator Training and Certified Crop Adviser credits have been approved for this field day.

Refreshments and handouts of the research will be provided.

Registration is $5.

For more information call 937-454-5002 or 937-239-6850 or e-mail jasinski.4@osu.edu.