JRP Decline and Death, Pollen Cone fungus?

I recently lost a Japanese Red Pine to a possible wilt and have been trying to figure out the problem post-mortem. Specifically, I thought I remembered a pine stream where Ryan was asked about removing pollen cones and responded that there was no need to remove them, but then mentioned that he or someone else had a fungal or other pathogen enter through infection of the cones. Anybody remember this from a stream or did I dream it? I have been unable to find it.

Here are the circumstances around my JRP’s death and I’m open to speculative causes. It was field dug in March 2017 as pre-bonsai, potted into APL 1:1:1 mix and not touched for a year. It grew nicely with 10” extensions and formation of back buds. It was needle thinned in the fall of 2017 to allow for sunlight penetration and encourage back-bud growth. In April 2018, it was reduced in height back to a lower leader and sealed. I took a picture of the base of the cut thinking I was going to count the rings. But it also serves as a before picture of the healthy resin ducts (interspersed white spots). I’m fuzzy on the timing, but I think sometime after the prune back it had pollen cones which seemed to dry up and cause death of the main candle and subsequently it threw a flush of buds then candles at the pollen cone sites. This may have been normal growth but I seemed to remember it as being odd. I only have one JBP that has put out pollen cones and it seemed different in the subsequent growth.

The JRP was healthy into Aug. 2018, until sometime in the Fall during a wind Santa Ana. A brick fell from the wall above the tree and snapped the leader. I repaired it with grafting tape and wire for support, but by Dec. 2018 the top was wilted. This is where it gets weird, because at the same time I noticed multiple other branches displaying a wilting look. By the middle of January the whole tree was limp and losing color. I unpotted and couldn’t find any healthy white root tips, but also didn’t see or smell any evidence of rot. I cut the trunk in half and didn’t see any of the staining associated with Pine Wilt Nematode. But the top portion of the tree, even past the broken leader and first few branches, had discolored resin ducts (red dots scattered among the sapwood). The bottom cut looked like the original chop did in April 2018, in that the resin ducts were white colored. Maybe the red color is from oxidation working its way down from the original cut and not associated with disease. I’m thinking disease due to the speed of decline in the tree and that is what made me think back to possible pollen cone issue.

Other causes could have been overwatering as we had a very wet winter. But this was in a free-draining inorganic mix with a hardware cloth and screen bottom.

Any speculations are welcome. Thanks!

Attached are pics at start of decline in Dec 2018 and then death and dissection in Jan 2019. These are the apparent healthy portions, but still in sections where the branches had wilted.

Whoops, lost service in the middle of nowhere. I will resume thread with pics at a later point.

Above is Jan. dissection of basal portion. Below is December decline and then January dissection of top portion.

image image image

1 Like