Sep 4, 2012

Don’t over-nitrate your apples

Have you had a problem with apples not turning the right color, or issues with spoilage while the apples are in storage? There is a good chance you’re over-nitrating your fruit, said Esmaeil Fallahi, a professor and director of the pomology program at the University of Idaho.

Fallahi has been studying the effects of irrigation and rootstocks on different apple varieties, and he took a careful look at apple nutrient uptake. What he found was that orchards with too much nitrogen produced apples with poor color and poor storage traits.

“Far too often, growers associate color with maturity,” he said. “They are most definitely not the same.”

Internal maturity of the fruit increases with too much nitrogen, Fallahi said. Green color also increases. The internal respiration increases, too, causing the apple to rot.

This all adds up to green apples that growers put in CA storage to ripen, but that are already ripe, Fallahi said. The result is spoilage and loss.

This has been a problem for growers across the country, but Fallahi has seen more cases in Washington state.

“This is an easy problem to fix,” he said. “It is something we’ve just learned, and many growers simply don’t know it yet. This is definitely information growers should share with each other.”

By Derrek Sigler, Assistant Editor