Translucent breakdown of the flesh tissue between the stone and the skin which occurs on the shoulders (stem-end) of the plum fruit and is associated with excessive softness and juiciness.
Bladderiness in plums is not common so very little is known about the disorder. It was first recorded in 1935 by Davies, Boyes and Beyers. According to them, bladderiness was associated with mixed maturities in export plums, where fruit which became overripe developed bladderiness. While little research has been done on bladderiness, we have noted the problem from time to time in cultivars such as Santa Rosa and Songold. Bladdery fruit has already been noted in plums at harvest, so it seems as if this internal disorder is not a chilling injury per se.
Causes and remedies
As alluded to above, very little information is available on bladderiness. In our experience, the risk of bladderiness seems to increase when plums are harvested following high rainfall. It could therefore be linked to excessive uptake of water by the fruit. As reported by Davies et al, we concur that it is more prominent in riper fruit.
Given the scant information on this disorder, we suggest the recommendations for IB and GB control following adverse weather conditions will also assist in lowering the risk of bladderiness development after excessively high rainfall. It is believed that fruit which are immature on the tree have a better chance of not being damaged. Therefore, if harvested a few of days after the high rainfall, the internal quality will hopefully be unaffected. In the case of mature fruit that must be harvested because it has ripened beyond the middle of the optimum maturity window, it is good practice to cut a sample of fruit through the equatorial axis to conduct an internal inspection for flesh tissue damage. After high rainfall it is also prudent to cut the fruit across the shoulder to check for bladderiness. Tissue damage detected at harvest, be it GB or bladderiness, indicates a very high quality risk. As progressive disorders, the levels of internal disorders will increase with longer storage so extended storage of such fruit is high risk.