(Dec. 10) RIO GRAND CITY, Texas — Imagine you are the sales manager for a melon company. You have to make sales based on the quality of the upcoming melon crop. Trouble is, the crop isn’t mature yet. Plus you’ve got several different varieties growing all at once, each with a different growing season.

This looks like a job for MelonMan.

MelonMan, a computer program that can predict the growth rate of melons, is the creation of Jeff Baker, a plant physiologist with the U.S. Department of Agriculture’s Agricultural Research Service. Baker began working on the program when he met David LaGrange, vice president and farm manager for Starr Produce Co., Rio Grande City, Texas, in 1998.

“They have a large farm, and they were growing a number of varieties,” Baker said. “The problem they were having is that each of these varieties had different growing seasons and the weather varied from year to year. A 75-day variety in one year might be an 85-day variety in another year.”

Baker said Starr needed a way to figure out when the fields would mature so they could schedule workers and trucks to get the fruit to market on time.

That’s where the MelonMan growth model comes in. Baker said the concept — timing the varieties with growing degree days, or thermal time — is one that has been around for years. This is the first time, however, that it has been used on a crop like melons.

“Plants go through a maturing process,” Baker said. “It’s driven by how warm they are. There are temperature optimums for different species. Each variety has its own rate of growth.”

Baker said the MelonMan model reads daily weather from a weather station that reports minimum and maximum temperatures for that day. MelonMan then uses that information to calculate how much the melons grew that day.

“It’s a way of using air temperature and growing degree days, as opposed to chronological time,” Baker said. “A plant response more to temperature and environmental variables rather than chronological time.”

Baker said the model is designed to simulate either a direct-seeded or transplanted crop. Many times melon growers will transplant crops because seeds tend to be expensive, he said.

The MelonMan program could be applied to other crops, as well. Baker said pea growers have been using the concept for many years.

“We didn’t really invent anything new,” he said. “We just took an old idea and applied it to melons.”