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WSU Extension Q&A: Why do grocery store apples have wax coating?

Apples produce a natural wax coating, but an additional food-grade wax is sometimes applied, because it increases the shelf life of the fruit.
Apples produce a natural wax coating, but an additional food-grade wax is sometimes applied, because it increases the shelf life of the fruit. New York Times

Q. Why do all the apples I purchase in the grocery store have a waxy coating on them?

A. Hundreds and thousands of apples running through a packing line is a modern marvel. Each one is washed, dried, photographed for damage and waxed. Apples, like many other fruits and vegetables, produce a natural wax coating, but an additional food-grade wax is sometimes also applied. This additional wax is made of organic ingredients and increases the shelf life of the fruit.

Q. When should onions be harvested?

A. Onions are ready to harvest after the tops have fallen over and dried. They can be harvested when the tops are green, but they will not last as long in storage. After the tops fall over, pull the onions so that the roots are no longer in the ground and let them sit for a couple of days without watering. Then, cut the tops off about 1.5 inches above the bulb and store in a dark, dry location.

Q. What are the shiny black aphids in my alfalfa field, and should I be concerned?

A. The only black aphid infesting alfalfa is called the Cowpea aphid. The nymphs are slate gray. The legs and other appendages are usually white with blackish tips. Cowpea aphids inject a powerful toxin into the plant similar to blue alfalfa aphids. There are no resistant varieties, or economic thresholds for cowpea aphids, so it is best to use blue alfalfa aphid thresholds. The thresholds are: when alfalfa is less than 10 inches high, spray when there are 10 to 12 aphids per stem, or when alfalfa is more than 10 inches high,, spray when there are 40 to 50 aphids per stem.

Recently, cowpea aphids were brought into our office for identification, so early fall is a time to look for them while monitoring for other aphids. Remember to look at the pre-harvest interval before selecting an insecticide. For more information and to see a picture of the cowpea aphids, go to http://bit.ly/1N2kaUJ.

Q. How old do kids have to be to join 4-H?

A. Kids 5 years or older and in kindergarten may join 4-H and be a member through the 12th grade. Call the WSU Extension office to find a club in your neighborhood.

Questions should be called in to the WSU Extension offices in Kennewick at 735-3551 or Pasco at 545-3511.

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