Remote-controlled drones that can fly over a farmer's fields looking for patches of weeds the pesticide spraying didn't kill, orom signs of those troublesome groundhogs.

Sensors mounted on the boom of a fertilizer applicator that use reflecting light to determine the health of a corn stalk.

Satellite images with infrared technology that a farmer can use to judge the health of his crop.

These are among the latest advances in a trend that has become known as precision farming.

Hiring trained "crop scouts" to assess the health and needs of farmers' fields by walking them is still widely used here. But high-tech options now open to local farmers could change that.

Each will be demonstrated Thursday at the Farming for Success 2013 field day, held by Penn State Cooperative Extension at the PSU Southeast Agricultural Research and Extension Center near Landisville.

Jeffrey Graybill, Cooperative Extension agronomy educator in Lancaster County, is having a ball with the new Drone Parrot that the local office bought for $300 with a grant.

But there have been some early learning-curve mishaps.

"Yesterday it came down in a soybean field when it ran out of power, and it took my son and me 45 minutes to find the thing," Graybill reports.

The lightweight foam and plastic "drone" looks like a cross between a model airplane and a helicopter and is called a Quadricopter. It has four skyward-facing propellers and is powered by a rechargeable battery.

Graybill uses an iPad in the field to control the drone with two virtual joy sticks. An iPhone also would work. The craft can go up to 500 feet high and do barrel rolls.

As the drone flew over fields near Landisville last week, high-definition video cameras — one with a wide-angle lens and one pointing straight down — sent real-time video of crop fields to Graybill's computer screen. He could push a button at any time to get still photos.

That's fine for a toy plane hobbyist or someone who wants to frame an aerial photo of his property. But how can these drones help a local farmer?

Graybill has used it a few times on his 30-acre farm outside Manheim for weed control and to look for swaths of nipped plants that indicate a groundhog lair.

The drones also could be used for aerial photos to document crop damage required by insurance companies. To date, farmers have relied on aerial photography by hiring commercial pilots.

Ken Diller, a precision farming manager for Hoober's Inc.'s office in Intercourse, thinks such drones could deliver infrared technology that shows crop stresses caused by insects, drought or diseases.

Both Diller and Graybill say drones likely will have more appeal for farmers with large fields and multiple locations, typical in the Midwest.

"My guess is it's more of a hobby for (local) farmers, but I don't know. It's a new thing," Graybill says.

Diller worries about the red tape the government is likely to require of drones, though it appears so far that non-commercial uses of drones are within bounds set by the Federal Aviation Administration.

Infrared technology is becoming more established here, Graybill and Diller say.

Amounts of chlorophyll in less-than-healthy crops show up in infrared images. Farmers can subscribe to a service that provides infrared satellite images of their fields on demand.

Nitrogen sensing is another high-tech option gaining more widespread use.

The amount of nitrogen a crop plant needs for optimum growth can vary from field to field or even within a field.

Research shows that plant-based measurements of nitrogen can be more accurate than soil tests.

Enter boom-mounted sensors. As they're driven over plants, they measure the amount of yellow light reflected off the crop. A computer uses algorithms to determine how much nitrogen the plant needs and, within seconds, adjusts the fertilizer applicator being pulled.

Handheld nitrogen sensors that clamp onto a leaf for readings have been around for years.

"I've used one on many Amish farms," Graybill notes.

Diller observes that mounted crop sensors currently are used "very, very sparingly" in Lancaster County because the technology is so new.

But, he's quick to point out, "I really believe it won't be too awfully long that we see that technology pick up tremendously. It just takes a while for people to use it."

This and other developing technologies and their higher initial costs, he says, "won't necessarily save you money.

"But they have the potential to make you money."