I planted this young pinus densiflora (tanyosho) a few weeks ago. It seemed healthy when I purchased & planted it. Yesterday I noticed there is a white substance building up at the tips of the new growth (looks sort of fluffy but is crusty and hard to the touch). It also seems to be flecked along some branches and needles. One tip is oozing yellow sap. In areas where there is significant build up, the young branches and cones have died (one is hollow inside, they are dry and malformed). It seems to be only affecting the top of the tree at the moment.
I have tried to do some research online and have come across pine needle scale, pine adelphid and fungal pine blight as possible causes, but don’t have the expertise to diagnose the cause. I’d like to learn 1)how to control this- the tree is young and small so I’m concerned pruning off affected growth may seriously damage or kill it, and 2) how to prevent the problem from reoccurring.
Any advice would be appreciated.
Paige
Thanks for contacting Toronto Master Gardeners. From your description and the picture it seems like your Pinus densiflora is suffering from a fungal disease. Possibly it is also being attacked by one of the insects you identify in your email but that is not as clear from the picture.
The key thing is that you bought the tree two weeks ago and it seemed healthy. Reputable nurseries and plant centres have at least a year warranty on the shrubs and trees they sell. I suggest you take the tree back and request a new one.
If that’s not possible, you may be able to get the nursery to help identify the problem. You can then try one ( or more) of the following depending on diagnosis:
• Cut back the affected areas plus two inches of healthy bark. Destroy the affected branches.
• Spray the fluffy areas with a forceful stream of water whenever they appear.
• Avoid using high nitrogen fertilizer
• Ensure the tree receives adequate water
• In the spring and fall you can apply dormant oil or insecticidal soap to the tree
Below are some sites for further information on how to manage pests:
https://hyg.ipm.illinois.edu/pastpest/200319e.html
https://www.gardeningknowhow.com/ornamental/trees/pine/controlling-pine-needle-scale.htm
https://homeguides.sfgate.com/white-stuff-pine-trees-80077.html
https://homeguides.sfgate.com/pests-diseases-pine-trees-43748.html
https://www1.agric.gov.ab.ca/$Department/deptdocs.nsf/all/ipd14865/$FILE/BackyardPestMgmt_coniferous.pdf