There are no hard numbers, but the NRDC scientist estimates as much as 20 percent to 30 percent of a crop could fall into the category of "fine to eat but cosmetically imperfect."
California farmer Craig Underwood, who grows fruits and vegetables in Ventura County, estimates that between 15 percent and 20 percent of some citrus crops such as lemons might get rejected due to scarring or insect damage. Sometimes the damage is due to unfavorable weather.
For Wal-Mart, the sale of imperfect apples marks only the second time one of its suppliers created a packaged or bundled special brand of imperfect produce. Earlier this year, the company sold a "Spuglies" brand of bagged potatoes at about 400 stores in three states after a Texas potato supplier was hit by bad weather and suffered a crop of blemished, misshaped and smaller-than-usual spuds.
"We have a flexible framework that the supplier can use when the harvest produces this type of produce," said John Forrest Ales, a spokesman for Wal-Mart in Bentonville, Arkansas.
According to the Wal-Mart spokesman, the use of brands such as "Spuglies" or "I'm Perfect" are examples of how the retailer can make the most of large quantities of imperfect fresh produce when they become available. But finding those large supplies is not always easy, and sometimes the grower may get a better deal sending the imperfect crop to food processors for things such as frozen food products.
"On the potatoes, it's not like these will be available all the time, because … Mother Nature has to give that supplier wonky or imperfect potatoes," he said.
Some of the growers of potatoes and other produce will donate their offerings to charities such as food banks. Legislation passed last year provided permanent tax incentives for more companies and farmers to donate food.
Feeding America, a nonprofit organization with more than 200 food banks in the U.S., is getting a substantial amount of unsellable produce from growers, retailers and food processors. In 2016, the group expects to receive more than 2.6 billion pounds from grocery stores, growers and other sources.
"Nobody wants to see food go to waste," said Ross Fraser, a spokesman for Feeding America. "We have nearly doubled the amount of fresh produce that we have provided for our food banks in just the last five years."