Pomegranate Rot

[Eykca]

What an exciting time of year! Some of the early varieties are getting close to being ripe. As I was looking through the fruit today I noticed one pomegranate on my Sirenyvi and one on my Eversweet that had a very similar spot of rot. I have uploaded some images from the Eversweet. I didn't notice any holes from bugs and there were no bugs inside. The fruit were not in contact with the ground. Anybody have any info on what causes this? Can it be avoided? So far it hasn't been much of an issue, only a couple fruit.

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[alanmercieca]

That is “heart rot” also known as “black heart,” It a fungal disease that starts at the "persistent calyx" of the flowers, and the disease starts to infect more of the flowers as they turn more in to fruit, if they start turn in to fruit. Sometimes the disease destroys the flower before it turns to fruit, and it also destroys male flowers as well. You have nothing to worry about if it's not infecting all of the fruit, and it can't harm the tree. Make sure to trim off where you cut that fruit at least 4 inches away from where the fruit attached, to cut off any disease that might be in the tree from the fruit, some people say that if it's not removed it could infect next years flower on the same branch.

[Eykca]

Thank you for the information. Armed with that, I took to Google and found there are 2 distinct types of Black Heart: one that reaches the rind of the fruit and the rot becomes external (as shown in my pics) and one that only affects arils and is undetectable until the fruit is open.

Initially, it was thought that the disease was caused by various fungi that can decay the arils. However, after inoculation of pomegranate flowers and developing fruit, it was concluded that the main cause of black heart is Alternaria spp. These fungi are very abundant in nature and cause diseases in a multitude of crops. Another fungus that is also isolated from pomegranate with black heart is Aspergillus niger. However, the decay caused by A. niger is softer than that caused by Alternaria and results in exuded juice. In addition, another major difference between black heart caused by Alternaria spp. and that caused by Aspergillus is that the latter decays both arils and rind of fruit and frequently symptoms reached the outer surface of fruit, which helps in the diagnosis of the disease.

From UCD website.

Either way, not much is known about these fungi and apparently not much can be done to prevent them. They do recommend removing all fruit while pruning during the winter.

[alanmercieca]

You are welcome.

[greenfig]

I have a few of those as well, not too many though.
The trees produced a lot this year and a few rotted ones is not a big deal. I hope it doesn't spread