DURHAM, N.H. — University of New Hampshire researchers are using a remote-controlled helicopter to help apple growers pinpoint problems and protect their orchards against blemishes that render the apples unmarketable.

The low-cost, unmanned aerial vehicle is loaded with GPS and infrared technology that can see pests or early infections caused by the apple scab fungus, which causes dark blemishes on the leaves and skin of apples. Instead of a farmer spending a full day scouting an orchard for problems, the helicopter can do daily surveillance in a short amount of time.

Kirk Broders, a UNH plant pathologist, and doctoral student Matt Wallhead are working with a Massachusetts robotics company to build the helicopter, which they expect to cost about $2,500.

“We aim to create an (unmanned aerial vehicle) that an independent researcher or grower could afford,” said Broders.

The researchers hope their vehicle could also monitor large crops like corn, soybeans, rice and wheat to detect disease outbreaks. They currently are fine-tuning their prototype and practicing by flying it over UNH-owned farms. The final product is about five years away from the marketplace, they estimate.

While Broders and Wallhead are one of the first research groups to use such technology for apples, similar vehicles increasingly are being used for non-military purposes, such as monitoring vineyards or tracking endangered animals.