Finally I get a season where there is no apparent damage from stinkbugs and coddling moth and my Korean Giant pear tree is loaded with beautiful fruit from medium to huge size, but most of the fruit is getting rot spots that end up being spread throughout the fruit when it is cut open. A small circle that seems to have a single puncture is all the evidence I have. I thought at first it was a wasps puncture that started the rot, but it shouldn’t cause such a destructive spread of rot, so maybe it starts internally and is the result of the long wet periods we’ve had this season.
25 years of growing this fruit here, and I never saw this before- the expression, “it’s always something”, applies to no endeavor more than growing fruit in the humid regions.
Sounds like the same thing I’ve been seeing on a large number of my Asian pears, particularly my KG’s which are my oldest surviving Asian pear trees, ever since the new stink bugs showed up but which I don’t remember ever seeing before, so I’ve assumed the stink bugs were responsible.
Small holes in mine resulted in significant rot. I don’t know what caused the holes. I plan on bagging a few and an additional spray hoping to solve the problem next year. Also poking a hole in one and seeing if the same rot develops would be interesting.
I am another in the Northeast that has had that problem with the spot-to-rot in Asian Pears this year. This is my first year with a significant crop on Korean Giant. The Yoinashi were impacted by it too.
I’ve noticed tiny holes either caused by OFM or ants tunneling through on my Shin Li and Korean Giant pears. I’m assuming some were also caused by curious birds.
I have had waspss making puncture wounds on my KG (a big target) for several years including this year. The extent of the damage was minimal compared to what stinkbugs and other similar bugs have done to my KG this year.
Wasp’s puncture holes and rot about 5%
Stinkbugs and co. 90 %
So you think maybe it is some toxic affect of BMS? There are none of the dimples I usually get from green stinkbugs. I have not seen any stink bugs on them at all.
I had a few KG have internal rot issues but noticed no external wounds on the fruit. I read somewhere that Asian pears tended to rot internally if left to hang too long. I attributed it to that. Maybe I overlooked some type of external damage.
This year was really my first significant harvest from my trees. To me pears were the least problematic and most pest resistant of all my fruit. Only a very small portion of my pears had any noticeable pest damage. Peach for me suffered the most pest problems and plums suffered the most fungal problems.
In 25 years or more of growing KG I’ve never had a problem with fruit left on the tree suffering from internal rot, even fruit I didn’t bother to pick that stayed on trees long after all leaves were gone. That is a problem with many varieties of European pears, but not something I’ve seen with any Asian pears I’ve managed over the years. I never harvest them before they are fully ripe and if I did they would never be sweet enough. When KG turns golden it is ripe and ready to eat- every year some pears on any given tree don’t get ripe enough before trees defoliate. They don’t adequately sweeten in storage.
However, the weather is changing and one of the greatest changes may be warmer nights and heavier dew. But if that is the cause, growers further south should already have experience with this issue.
Also, in searching, every university guide I see about stink bug damage, including BMSB, suggests the corky spots with dimples are a universal symptom of their damage. It simply does not exist on my pears this year.
I guess I will send some pictures of fruit to my cooperative extension agent who will forward it to a plant pathologist at Cornell. This almost never leads to any definitive or useful answers, but you never know. If I get any response I consider of interest I will post it here.
Maybe I should try to get some help from UC Davis as Asian pears are a big enough commercial crop there that they have a mandate to invest resources on managing its pests. I don’t think the gurus at Cornell really have much experience with the species.
Getting plenty of rot like you on Korean Giant. I’ve physically seen large numbers of stink bugs. Some European pears are rotting as well. Korean Giant has the biggest problem with it.
The coincidence, at least in my experience, of the two not being a problem at all in previous years and then appearing together just seems highly suspicious.
The lack of dimples and corking as well as sightings to go along with the rot is what seems suspicious to me- suspicious that there is another cause. Not sure what you are suggesting you find suspicious.
Before this year, stink bugs and coddling moth had become such a problem that I cut one old KG tree down, even though it was a beautiful specimen. I purposely planted one in an area less prone to stink bugs but it didn’t help a lot, and certainly not for coddling moth damage. Before this year, the tree was barely worth managing because of that damage. Now it’s still barely worth it but with a different problem.
The top photo looks like my pears this year, the bottom like a lot of my pears in previous years. Thanks, that illustrates what I’m talking about. If I cut open a pear that looks like the top photo the rot extends almost throughout the pear making it worthless.
I placed 3 wasp traps on my tree in hope it might stop more pears from being so damaged. I don’t really need that many.
The one with a wasp. Puncture wound also got coddling moth tunneling in from the calyx end, too. Most of my KG sustained more than one hit and more than one pest as well.
In all fairness any very late pear or very early pear is a target on my property. Korean giant has been targeted the worst of any pear I grow but I’m not sure why.
