Apricot skin blemish
We have one apricot tree with good size fruit, but they all develop skin blemish and the skin in those areas (about 1" dia.) turns brown, leathery and develops cracks.
The fruit is delicious but unsightly.
We don't know the type of apricot tree and it's about 5 years old.
Attached are a couple of pictures. The fruit are not quite ripe yet.
Any ideas? Thanks for your help.
San Luis Obispo County California
Hi Max --
Apricots can be susceptible to various fungi that cause fruit rots, but from your description and photos, that doesn't seem to be what's going on here! Most of those start with spots on the fruit (brown, or maybe reddish ones) that grow and eventually turn into soft spots. Rots also happen when fruit is injured and fungus takes hold in the injury, such as in a fruit that has cracked.
Cracking alone can come from irregular water availability, with different varieties of apricots (and other fruits, notoriously tomatoes) being susceptible to different degrees. "Excess" water, especially at a time nearing harvest, can cause fruit to swell rapidly and crack.
But this still doesn't explain the leathery skin patches! Since you're eating this fruit -- "delicious"ly! -- it sounds like the skin problems are neither progressing to a fuzzy mold nor a soft, watery rot.
I'm going to "go out on a limb" here and suggest your apricot tree may have one, or both, of two physiological (as opposed to disease) issues: First, it's hard to tell from the photos, but if the leathery patches are occuring always on the "sunny side" of the fruits exposed to sunlight, there may be some sunscald going on. This can be a byproduct of growing a variety that isn't well-suited to its locale, but can be helped by judicious pruning and blossom thinning to help keep fruits shaded, along with adequate moisture.
The other suspect would be a nutrient deficiency, possibly boron. The leaves in the photos appear healthy and happy, but while many nutrient/fertilization problems affect foliage, a boron deficiency in apricots is known to cause cracking and corky-skinned fruit.
Max, I'm going to refer you back to your local UC Extension office in San Luis Obispo. This page:
gives you the direct contact information of various specialists on staff there. These are the folks that will know about your local conditions (soil nutrient profiles, local apricot problems), and can recommend resources for nutrient testing (foliar, soil) if they feel such may be needed.
Good luck -- Here's hoping that with a bit of intervention, your apricots can be as gorgeous as they are tasty!
Thank you for your response. It was very informative and I will contact the link in SLO.
I am sending you another photo from our second tree that bears fruit a couple of weeks later than the one I sent you. No need to respond, just FYI. This has more of the symptoms you describe.
Anyway, thanks again for your time and help.
Yep, these spots are less of a mystery! What you're seeing is classic "brown rot" of apricot, caused by Monilinia fructicola (and/or M. laxa), the most common cause of post-harvest problems, as cited by the University of California at Davis' Post Harvest Technology Center (yes, there is such a place!). Here's their apricot page, click the "brown rot" link to see a picture from there:
Although post-harvest symptoms can be controlled somewhat with cold storage (since these are your trees, I presume you're not harvesting early!), the fruit is inoculated in the orchard, often at blossom time. This is a scourge of stone fruits everywhere -- here's a very thorough fact sheet on the disease (concentrating mostly on tree and pre-harvest infection) from West Virginia University's Kearneysville Tree Fruit Research and Education Center:
Orchard sanitation is critical in preventing infection; commercially grown apricots are generally subject to a comprehensive fungicide program. UC-Davis has information on fungicides and application timing, but again you might want to check in with the folks at your local extension, especially regarding growing issues with fungicide resistance, as well as organic alternatives (sulfur-based "organic" fungicides are not recommended for apricots). If you take a look at the fungicides-for-apricots page:
You'll see there's not much guidance for the home or organically-inclined grower included in the options!
Here's hoping you can get all your apricots back to optimum condition -- both on tree and afterwards!