I am very interested in mangosteens and also cultivate them commercially.
We began planting mangosteens in 1988. The first ones flowered and fruited after 8 years. Some have taken 12 years, maybe more. We have 31 in production and the harvest, just of these, can be daunting.
The quality tends to be very good initially but then we begin to get fruits with "gamboge" or a hardening of the pulp as it becomes translucent. In general these problems easily appear on fruits that have otherwise perfect presentation. We can't tell if the fruit is bad or not! What has anyone found out about these problems?
Incidentally, we are in an area with high, well distributed rainfall, 4M, per year. There are two drier times but these don't last for long. It is unusual for it to go more than 2 weeks without measurable rainfall.
Accepting the commonly held perception that these tropical fruit trees need a dry period at some point to help induce flowering we set out to determine statisticaly when this period might be so that we could cleverly lay out tarps under rambutan trees to induce them to flower instead of simply put on more foliage.
We weren't able to find any correlation in reviewing years of careful rainfall recording and fruit production data to prove that the rainfall clearly affects rambutan and mangosteen flowering. We can easily get two crops a year in this part of CR but in the areas that have a six month dry season they only get one harvest per year.
I am especially interested in controlling internal fruit damage in mangosteens if anyone has any experience with this problem.