Like Tahitian limes, finger limes are reported to occasionally suffer from stylar end breakdown (SEB). SEB is a physiological disorder which leads to the breakdown of the rind. It begins as a brownish, water soaked area, most often on the stylar end (bottom) of fruit and if it progresses can cover ¼ –½ of the rind. The area then becomes dry and sunken below the surface of the remaining rind. The symptoms can appear while fruit are still on the tree or after harvest. The damage is caused by the rupture of the vesicles in the outer surface of the pulp. The juice released then invades the rind where the acid ruptures the oil glands. Older, larger fruit appear to be more susceptible.
Finger limes are also very susceptible to oleocellosis — rind damage caused by the accidental release of oil from the damaged oil glands. The released oil ‘burns’ the rind and within 2 to 3 days an unsightly blemish develops. The damaged surface of the fruit becomes dark and rough. The symptoms of oleocellosis usually appear after harvest and are more prevalent when wet, cold or turgid fruit are picked.
Careful postharvest handling will reduce the incidence of both oleocellosis and SEB. Do not harvest wet or damp fruit and avoid harvesting fruit early in the morning when fruit turgor is high.
Some commercial growers report that the variety ‘Rainforest Pearl’ and other light-green skinned cultivars seem to be more susceptible to skin damage and postharvest rind disorders and breakdown – so careful postharvest handling, packing and storage is critical, especially for export consignments.
Fruit are also very susceptible to wind rub and sunburn, which are major causes of damage and fruit downgrading. Growers also report that fruit close to maturity have a tendency to split during wet weather. Deformed fruit are usually the result of poor pollination.
Harvesting
During all harvest operations the fruit, especially light green skinned cultivars, should be handled carefully to prevent skin damage and postharvest breakdown. Because trees are thorny it is recommended that pickers use some form of eye and hand protection during harvest.
Fruit are hand picked for colour, size and maturity every 10–14 days over a period of 6–8 weeks. For some cultivars fruit harvest may extend for up to 2–3 months if there have been multiple or extended flowering periods.
Fruit must be fully ripe when picked as finger limes do not ripen off the tree. Ripe fruit tend to feel full and detach easily from the tree. To test fruit ripeness, score the fruit around the middle, twist to open and then gently squeeze – the crystals should come out separately and freely. Unripe fruit tend to have a bitter taste. When opening fruit avoid getting the oil from the fruit skin onto the crystals as it can taint their flavour.