Thinning apples with table salt

I was having a conversation with a friend after Mass on Sunday. My friend usually attends one of the earlier services so it was a treat to see him and his family.

My friend stays up-to-date on healthcare and his wife is very involved in organic food and nutrition.

In passing, he mentioned that a home fruit grower can "thin" apples with a solution of common table salt. Yup, good old sodium chloride.

He also mentioned that even though salt water covers more than 3/4 of the earth's surface, a grower cannot get apples certified as "organic" if you spray your trees with salt water.

"Huh?" I said.

"Somebody has to pay money to get materials certified as organic. Nobody can make money off salt so nobody is willing to sponsor certification." was his answer.

Organic or not, using salt water to thin fruit is a great thing especially if you are growing varieties like Golden Delicious, Gala or Jonafree. Those are work-horse varieties that want to produce too many apples.

Average fruit weight is a reasonable proxy for flavor as they are both driven by availability of carbohydrates. Fruit thinned with 1.5% salt were 26% heavier than the control. The average of the three vegetable oils at 3% was 31% heavier than the control.

According to this paper, growers can thin fruit, which will increase fruit size, and increase sugar content and smooth out biennial bearing by spraying the trees at full bloom with 1%-to-1.5% salt water. You might want to give it a good squirt of dish soap to ensure good wet-out.

2 ounces of salt in one gallon of water is mighty close to 1.5%. Other research suggests that 1.5% is the maximum strength that should be used as over-thinning occurs at higher strengths.

Other thinning options included spraying with half-strength vinegar (3% acetic acid) or 3% emulsified vegetable oil.