I can deal with many fig tree diseases, but seeing figs mold while still on the tree pains my heart. For someone who adores figs, as I do, losing a portion of the fruit is the worst thing that can happen. But nature is cruel, I guess.
Let’s see why figs develop mold while on the tree.
Figs mold from too much water and many different fungi species, including Alternaria alternata, which causes well-known Alternaria rot disease. The molding process is almost always triggered by excessive amounts of water on the tree or taken by the roots from the soil.
Now that we have cleared that out of the way let’s dig a bit deeper into the details.
Can Figs Mold From Too Much Water?
Figs can mold from too much water. Climate with too much humidity is the main cause of fig mold, and it helps in spreading diseases that cause mold. Preventing figs from molding can be achieved by not over-watering and pruning so that increased airflow can dry the tree.
Fig fruit is supersensitive to high amounts of water once the ripening process starts.
When there is huge rain during summer in my area, some of my figs immediately after the ripening process start to form a layer of fuzz on them. I can have some decent figs if I detect it early enough and pick the fuzzy ones, but if I forget to remove the contaminated fruit for even a few days, it’s game over. That fuzz soon enough starts to form into the mold.
I’ve identified this as a problem that happens only when there is too much humidity for weeks in a row. Unfortunately, I live in an area like this, but I’ve managed to solve this issue by pruning and regulating how much water my figs get from the ground.
Fig mold can appear from excessive irrigation as well. Knowing how much and when to water your fig trees is crucial for fruit development and quality.
How To Prevent Fig Tree Mold From Too Much Water?
Since rain affects the amount of water on the tree and the amount that a fig tree takes up by its roots, let’s start by discussing how to minimize the damage from above-the-ground humidity.
Fig trees grow best in dry, warm climates. They can live in the cold to some extent, but humidity hurts them more easily.
The only way I know to regulate humidity in treetop is by pruning. I do my best to prune each winter in a way that leaves the middle of the tree as empty as possible. It’s practical to do it from a fig tree’s early years because it will somewhat follow that form later on. That way, it’s easy to cut new branches from the middle when they appear.
The form that a fig tree takes by pruning this way provides enough airflow to dry all the water before the fruit starts molding. Additionally, the north side of the tree gets more sun which helps with dryness and promotes growth.
To regulate how much water my fig trees take through the roots, I plant them on raised ground. This planting method is great for areas with lots of rain, and it’s easier to irrigate because any extra water won’t pool underneath the tree. In my orchard, I plant figs on ridgelines of my making, while I prepare a raised bed for any fruit tree I plant in my garden.
I’ve written a separate article that goes into more detail about how much water a fig tree needs in different climates and at different stages of its life. You can read it here.
Fig Mold Caused by Alternaria Rot (Alternaria alternata)
The thing is, fig mold caused by too much water is actually caused by fungi. However, there is a difference between these aggressive fungi like Alternaria alternata and commonly present fungi which get triggered into growth by huge amounts of water. By aggressive, I mean fast-spreading and resistance to chemical treatments.
Many fungi can cause both surface and inner mold in fig fruit, although most of them are quite rare. To even mention them would require a whole book. However, by far the most common one is Alternatia alternata which causes Alternaria rot.
I believe all cultivars are susceptible to the illness, although Kadota, Conadria, and Calimyrna are particularly vulnerable. I don’t get mold on my figs often, and even when I did, I never tested it to see which fungi I am dealing with. Luckily, I worked on other people’s figs and helped them treat Alternaria alternata, so I have some experience.
On ripe fruit, Alternaria is most prevalent if there are rains during harvest. In the early stages of Alternaria fruit rot, water-soaked spots develop on the skin where 2 to 3 figs come into contact. It’s similar to mold that happens from too much water, at least in the very beginning, but much faster spreading. Spores of a dark green color rapidly cover these spots. Black fungal mats form within the cavities of Calimyrna and Condria figs as a result of Alternaria rot, which begins at the fig’s hole on the bottom.
Spotting can be up to 0.2 inches in diameter and varies in color from a pale yellow to a dark brown or black. This color variation can be a good sign that you are dealing with Alternaria rot.
How to Treat and Prevent Alternaria Rot on Fig Trees?
Unfortunately, no effective treatment is yet discovered for most fungus species.
However, there are many ways to prevent Alternaria alternata and other fungi. One of which is making sure there is enough airflow within the treetop that I mentioned before.
Another solution is to pick figs before heavy rainfalls spoil them. Obviously, you can do this only if figs are already ripe or closely ripe. They could finish riping off the tree if they needed only a bit more time. In most areas, fig mold happens after the fruit is ripe, so it can be completely prevented by picking figs on time.
My advice is, if you suspect Alternaria rot, cut all the infected figs immediately. Luckily, it affects up to 25% of fruit at the very beginning of the disease. If you catch it on time, you can save the remaining 75%. The remaining figs don’t need to be sprayed with anything. That can only help the disease at this point. Instead, hope for some dry weather.
Fig mold caused by Alternaria alternata can be stopped by sudden dry weather. Infected figs won’t recover, but the disease will stop from spreading.
Other Common Fig Tree Diseases Which Have Mold-Like Appearance on Fruit
Some diseases which commonly attack fig leaves can cause damage to fig fruit as well. I’m mentioning them here because a few of them look almost the same as Alternaria rot on its first day, and they can eventually lead to fruit molding in later stages of diseases they cause.
One of the look-alikes is fig rust. At the very beginning, it forms small dark spots like Alternaria alternata. Unlike the Alternaria rot, these spots form in places where figs don’t touch each other. Other than that, fig rust causes premature fig ripening that can lead to molding.
Fig blight can also affect the fruit, especially if it’s a newly formed fruit. It doesn’t look like molding, but it can cause figs to rot and be susceptible to mold.
Fig souring would be the reason for the mold. However, the rot happens from the inside, and fungi that cause it rarely mold. Even when mold appears, it’s hidden inside until the fruit visibly rots. It would be more relevant if not for the fact that you would notice the rotting fruit way before any mold happens.
If you want to learn more about the most common fig tree diseases, you can read my article: Which Disease Is Attacking My Fig Tree? – Common Diseases on Fig Trees.