Fruit trees are beautiful in April and May. By mid-May, if things are going well, our orchard is full of beautiful fruit trees in full bloom. But spring is also the bridge between winter cold and summer heat – 80-degree days have us digging for flip flops, while overnight frosts remind us that winter is not ready to completely let go. These temperature fluctuations can wreak havoc on tree fruit crops. Warm spring temperatures followed by late spring frosts – conditions that are occurring with greater frequency in recent years - can result in partial or total crop loss.
You might be surprised to know that the difference in temperature between minimal vs. total crop loss are very small. When the fruit trees have all those beautiful blossoms, a 30-minute exposure to an ambient temperature of 28 degrees F will result in approximately a 10% crop loss, whereas a 30-minute exposure to 25 degrees F will result in a 90% crop loss! With such small margin for error, local weather reports that predict “overnight frosts” are not specific enough to gauge the effect on our crop. And, because our farm is its own “microclimate,” the temperatures in our orchard can differ significantly from the predictions of local weather reports.
Finally, unlike most vegetable crops, tree fruit cannot be plowed under and replanted within the same growing season. So, once our crop is lost, there is no recovery available within the current growing year.
Frost has wiped out our tree fruit crop twice since we started Small Ones Farm. In 2014, we decided to make a significant investment in the tools necessary to prevent frost-related crop loss: a way to measure real-time temperatures in our orchard, and a way to combat temperatures that are low enough to wipe out our crop.
With help from our friend Larry Manire at Databasics, we installed wireless sensors throughout the farm: in our orchard, hay fields, high tunnels and refrigerators/freezers. These sensors provide real-time temperature and other data, which alert us to conditions that threaten our crop. On several nights this spring, the wireless system sent us urgent texts in the middle of the night because crop-killing cold temperatures had been detected. Not only has this helped us take steps to protect our crop but the data we’ve gathered confirms our long-held suspicion that our farm is its own “microclimate:” temperatures on our farm have deviated as much as 12 degrees F. from local weather stations!
The Miracle Machine:
Picture a green gizmo that is about the size of R2-D2 and has the heating capacity of a large furnace. That’s the thing that rescued our crop this year. It’s called a Frost Guard and it’s made by a company that is based in Belgium. The way it works is to blow warm air at the base of the trees in the orchard. Because it blows really hard and continuously rotates 360 degrees, it is capable of warming a large area (over an acre). The Frost Guard is fuel-efficient and quiet, so our poor neighbors didn’t have to join Bob in a middle-of-the-night orchard walk. On four occasions this spring, Bob received 3 a.m. texts from the wireless detectors in the orchard and marched out with his head lamp and a warm coat to fire up the Frost Guard. Based on the measurements we gathered, the Frost Guard raised the temperature in the coldest portion of the orchard by 3 degrees F – enough to prevent significant damage to our fruit crop.
When we’re all enjoying peaches, pears and apples, we’ll celebrate the miracle of nature, with a little help from technology.