Reflective materials that bounce additional sunlight up into tree canopies from the orchard floor can pay off in higher yields, bigger sizes, and better and more evenly colored fruit.
Tests over the past eight years with reflective fabrics placed in drive rows produced similar results in apples, cherries, pears, peaches and nectarines, says Tory Schmidt, a research associate with the Washington Tree Fruit Research Commission in Wenatchee.
“I was a little surprised at how consistently effective they’ve been at those three qualities,” Schmidt says.
'Pretty substantial' results
Results include a “pretty substantial” impact in size, fruit set and yield. Yields in test plots, for example, have run up to 20 percent to 25 percent higher, he says. Mylar foils used in the tests improved only fruit color.
Higher yields, larger fruit and better color “all put money back in the grower’s pocket,” Schmidt says.
While reflective materials so far are more common in Western orchards, the extra light also is crucial for Michigan cherry growers using high tunnel systems with blush varieties.
“We’re already light-limited [without high tunnels] so every little bit helps,” says Greg Lang, professor of horticulture at Michigan State University in East Lansing.
Adding to the problem, the plastic used in high tunnels partly blocks ultraviolet light.
And without UV light, only the topmost layer of Rainiers and other high-value blush cherries achieve full color. The rest, he says, stay pale yellow.
Convincing results in blush cherries
Lang hasn’t found funding for a full range of controlled experiments with the reflective materials.
But he’s done enough preliminary work with three types—Extenday reflective fabric, Mylar foil and a white weed barrier fabric—to show convincing results with blush cherries.
The jury is still out for the region’s growers with Bings and other sweet red varieties, or for those not using high tunnels, he says.
Any added expense requires careful consideration.
Choices, choices, choices
Which reflective material to use depends on your objectives for a particular block, says Jonathan Toye, founder and chief executive officer of Extenday USA Inc.
The company, based in Yakima, Wash., offers 10 versions of its reflective fabric, varying in weight, durability, reflectivity and weave construction.
Growers’ objectives also affect how they use the material, when they deploy it and whether they shift it later in the growing season to aid a different crop, Toye says. “Think about it as a management tool,” he says.