Last summer our peach tree made the most beautiful looking fruit yet when you broke into the peaches they were rotten inside. What would cause this & what, if anything, can be done about it to prevent it from happening again this year? The tree is already starting to make peaches again...
There are three schools of thought that cause the deterioration of the flesh in Peaches as the fruit is ripening. 1. The most prevalent thought without seeing the actual damage and the color of the rotting is that there is IB, internal breakdown of the flesh caused by a physiological disorder. There are certain varieties of Peaches and Nectarines that are more susceptible than others in yielding fruit that have ongoing flesh decay without showing any outward characteristics in or on the fruits skin. No lesions, no browning, no nothing to let you know in advance of something wrong internally. Also, improper storage of the ripe fruit after picking can cause an IB condition to come about. 2. For a long time it was thought that Brown rot and Hull rot, both Monilinia laxa and Monilinia fructicola could cause the flesh to breakdown. I feel that most of the symptoms we have in the fruit of Peaches from these diseases can easily be identified by the rotting of the basal end of the fruit which becomes noticeably discolored due to the soft tissue breakdown and then subsequent rotting. That to me is Hull rot. Brown rot is a little more tricky in that in most cases we will see a wet spot on the fruit, generally not in the basal end but somewhere else such as on the body of the fruit and even the top portion of the fruit. The other difference is we will see a whitish mycelium build up much sooner than from Hull rot. It is still possible that Brown rot, at one time it was thought that it surely did much more so than Hull rot, can also cause internal damage without symptoms showing on the outside of the fruit (mainly Peaches as it is rarely seen on Nectarines). We can suppress both diseases by fungicide sprays when the tree is in early bloom to late bloom as well as cultural practices to remove and discard of any mummies left on the trees. It is the latter that is quite important but a Copper or Calcium Sulfate spray, for example, during bloom prior to petal fall is almost imperative. 3. Here is where I will get into trouble but I know it is true but I am not sure to this day there has been much scientific work done on it. In some varieties of Peaches and Nectarines there is a gap that starts to develop where the stem meets the top portion of the fruit. I've often wondered where and how certain fruit beetles could enter a Peach and Nectarine without any outward appearance of an attack on the fruit. After some close inspection I saw where the beetles could enter as with the weight of the fruit there is an abscission like layer at the top where it meets the stem that causes a very small opening into the fruit. It is there that a bacteria or a fungus can attack the internal portion of the fruit without us knowing it until the fruit is sliced in half. In Red Delicious Apples it is called Moldy Core caused by Alternaria alternata. I believe the possibility that the same pathogen can also attack a Peach and in some rare cases Nectarines. Instead of an opening at the calyx such as on an Apple, an opening between the lower portion of the stem as it is attached to the fruit, which can allow the fruit to fall off the tree on its own can cause the entryway for the rotting problem you are experiencing. Either you have a physiological disorder going on with the particular variety of Peach you have or you have an invader coming in while the Peach is ripening. For the latter there is no recommended control or suppressant for that close to harvest. Should your Peaches continue having the same rotting symptoms in the next few years after using a fungicide regimen in the early Spring, then you may want to discard your tree and grow another variety of Peach instead. An excellent question and one that the scientific community would have some real problems trying to answer. There has been some real discord between Farm Advisors and Pomologists over this issue for years, at least 35 years that I know of. Next time join the UBC forums. I generally do not respond to unregistered posts. Jim
Thank you for making the exception & answering in this case. I'll pass all this info on to my father (he does most of gardening in the family) & will join the forums soon.
Hello: Fruit Trees are one of my areas of long term interest. I am still learning them! You asked such a good question that I could not leave it alone. I initially learned the problem you are having as being due to Brown rot. Later on I was told that certain varieties of Peaches could in some cases experience an internal breakdown of the flesh which was and still is considered quite a rare event for us to see here in the San Joaquin Valley. The IB problem with varieties of Peaches is more prevalent in cooler and more humid areas than ours. I do not know where you are growing your Peach or your variety but you will want to initiate a fungicide spray program in the very early Spring as there are no real alternatives should you have a Brown rot problem. For an IB problem caused due to a variety you can help it somewhat with the help of timely fertilizations with a granulated fertilizer having about 10% Calcium as a nutrient amendment such as in the Winter while the tree is dormant and best done in the early Spring. Any granulated fertilizer application during the growing season must be accompanied by a few deep waterings to better incorporate the fertilizer down to the root zone without injuring the roots. Please do join the forums, everyone is welcome no matter the novice in plants, the backyard grower all the way to the professionals. Jim
