Apricot disease or disorder
I have an apricot variety that shows the symptoms on the pictures. It starts to show symptoms in green fruit stage as dark veins and usually at the flower end part(usually upper half of the fruit). At the green fruit stage it looks like veins, however when the fruit is mature it is like brown leathery patch. This symptoms occurs every year and especially when number of fruits are higher.
Outside United States
It looks like a something caused by the environment at an early stage in the fruits development. It could be a reaction to one of the chemical sprays used during early stages of growth or weather related. Your best solution would be to talk to some one in your region and compare growing methods. I would need additional information including chemicals used if any and where you are located to give you a better answer.
It does not look like a disease but could be insect related, maybe Thrips.
I've attached the pictures from the early fruit stage. I have 3 other varieties in the same orchard yet they dont develop anything like that, even there is 4 trees of another variety, mixed on the same row with the problematic variety when planted, yet they dont have anything like that either.
I am located on the southwest Turkey, city of Antalya by the mediterranean coast where basic chill accumulation(hours between 2and 7 ℃ ) on december and january combined was 350 hours(prior to 2015 harvest, it was only 180 hours in december and january total). Spring is usually sunny in here. As for the chemicals i will check my records and post it.
Thanks for the additional information. Since it appears to be only one variety I am thinking it might be a developmental characteristic, Jacket Rot is where there is a delay of all the flower parts dropping as the fruit is starting to develop. One or more of the flower parts remain tight to the developing fruit, eventually dropping off, this delay causes the physiological damage that eventually heals. This would explain the fact that only one variety is affected since it is a characteristic of that variety only. Careful observation during the bloom and petal drop period might answer your question for sure.
I do not know of a solution for this.
Thank you Michael. To give further information, last year due to warmer december and january, fruit setting was lower, about between 600-700 fruits per tree(no thinning) and not significant number of fruits with this disorder; however this year cooler december and january and fruit setting was higher with about 1000 fruits pertree(not thinned). In the last 4 years, only last year this problem was not significant, and the major difference i can think of last year was that average number of fruits per tree was about 35% lower.
There is no other orchard that i know of in my area to compare fruit quality and cultural practices, however there is one orchard in different region that has the same variety and they dont face this problem(and they DO thinning). I feel like there is a relation between this problem and number of fruits left on the tree.
But I have no idea what may be the basis for this correlation!
Crowding of the fruit could affect the rate of fruit development, and spray coverage.
The pictures look like something was touching the skin causing some damage. My thought would be to determine the point in the fruit development that the damage starts,
Thinning is a good practice with fruit trees because you could have a more consistent crop every year. Maybe 800 per year every year instead of the up and down plus it is less stressful on the trees.