As workers toss pumpkins onto a truck in a field near Ripon, pumpkin grower Bryan Van Groningen is keeping a close eye on his crop.

"The pumpkins have pretty much reached full color. The vines at the point where it's mature," said Van Groningen, Vice President for Van Groningen & Sons headquartered in Manteca.

The company has 1400 acres of pumpkins and grows 35 varieties of the squash, mainly ornamental, for carving or display.

But this season has been a challenging one.

Historic rains in the spring and extreme heat in the summer provided a "one-two punch" that has dropped his yield by up to 25 percent.

"We do have probably one out of every 3 or 4 fields that are subpar due to the heat," said Van Groningen.

San Joaquin grows 80 percent of California's pumpkins, making it the largest producer in the state.

It's a $20-30 million industry in the county.

Because of the rains, planting season was delayed and the heat damaged flowers on the plants reducing the size of the crop.

For consumers, Van Groningen doesn't believe the pumpkin shortage will cause a jump in prices.

However, he says there is a possibility pumpkins may disappear from store shelves a few days before Halloween.