Nectarine Fruit Scarring Due to Thrips Damage

Q. My nectarine fruits have this corky appearance on the outside on their skin. They do this every year. I don't apply any pesticides. I sent you a picture. Why does this occur?

Nectarine scarring noticed by reader.

A. I will post your picture on my blog as well as some others which are similar that are common to nectarine.

Thrips damage to nectarine fruit at the UNCE Orchard

            Nectarine fruit is a hairless peach fruit. Not having this hair on the skin allows a lot of things to damage the fruit. Hair gives a lot of protection to fruit and slows down water loss from the fruit as well. When the fruit skin is damaged by blowing sand, disease, and insects the skin reacts by growing a corky surface which we could relate to as “scabby”.

            Instead of scabby, we call it russeting of the skin. In plants we are probably most familiar with Russet Burbank potato which has that naturally rough, dark brown, corky skin.

            Russeting is due to damage to the skin. If this type of damage continues, the entire fruit could be covered with this corky surface. From your picture it appears that it's started and then stopped for some reason since it only covers a small portion of the fruit. So we are looking for something that happened to the fruit when it was pretty young.

One of the several products that contain spinosad insecticide. Thrips control is difficult.

            The usual reason for this in southern Nevada would be thrips damage. Thrips are tiny insects that cause damage to soft plant tissue very early in the spring. If they are left uncontrolled this damage can cover the entire fruit or even cause the fruit to drop from the tree.     I was a little confused because the damage was only in a small area of the fruit and you did not use any pesticides to control them. But with uncontrolled thrips you would have expected the damage to continue and cover the entire fruit.

            I forwarded your picture to a friend at Dave Wilson Nursery in California and he confirmed the thrips damage. You would apply Spinosad insecticide, an organic pesticide, with the wetting agent so that the entire fruit is protected from thrips. You apply this immediately after flower petal fall in the spring for about three applications about a week apart.