Brown spots and red discoloration on young Nyssa silvatica

Question: I have noticed brown spots and red discoloration showing up in the last week on my young Nyssa silvatica "select" tree. The tree was planted last summer on a slight slope with deep soil and good drainage. It is planted in a Dahlia bed, and receives water via underground drip (emitters at 12 inches and rate of 0.9 gal/hour) three times per week for approximately one hour (for the Dahlias). It has full sun exposure, though it is planted close to a Circidipyllum japonicum on one side. There are Arbutus unedo (dwarf) behind the tree.

responder: Signe Danler, Online Home Horticulture Instructor Replied July 06, 2023, 2:03 PM EDT
response: Hi, Alan, Thanks for your great photos and description of the growing situation of your Nyssa sylvatica tree. That helps a lot.  Nyssa is not native to our climate, and is relatively new to the PNW, so there is not a lot of information about growing it here. After a diligent search, I was unable to find anything definitive. Nyssa is considered to be a very trouble-free tree, but it does seem to be somewhat prone to leaf spots. Generic leaf spots - I have not found reference to any particular pathogen. Apparently it is just one way it responds to some stress. The spots seem to be quite common in fall, so seeing them in spring I would guess there is some stress on the tree. The growing conditions you have given it should be suitable for it, so I really just have a couple of suggestions. First, take one of the infected leaves and look at it with a magnifier (or take it into your local Extension office for a Master Gardener to look at) and see if you can see any evidence of fungal spores. This may be a fuzzy look or small black spots. Regardless of whether you can definitely identify a fungus, good practice is to remove and dispose of infected leaves. This will reduce further spread of whatever it is.  It looks like your tree is basically pretty healthy. As long as only a few leaves are involved, I wouldn't worry about it, just keep giving it good care. You may have to live with some spots on it.  Long-term, it may not be compatible with a Dahlia bed - it will shade the sun-loving Dahlias, and they will compete with it for food and water. Also it may be too close to the Arbutus for both of them to reach full size comfortably.

responder: The Question Asker Replied July 06, 2023, 9:23 PM EDT
response: Thanks so much for getting back to me so quickly. I looked at the spots and discoloration more closely under magnification and do not see an indication of fungus in terms of fuzzy spores or small black spots. I've taken the liberty of attaching those close-ups on the off chance they provide enough additional detail to spark some recognition. They are spreading to a larger percentage of the tree, so cannot be removed without causing damage. It may be my only hope will to hope for better next year after leaf fall - obviously making certain to dispose of all leaves - and then hope further that the tree outgrows the problem. If I have the same problem next year I may have to remove the tree and replace it with a more reliable option for our area. Interestingly, I have another Nyssa planted across the garden that is not showing this issue, which makes me wonder if it is something in the soil local to the tree. Anyway, thanks again Alan

responder: Signe Danler, Online Home Horticulture Instructor Replied July 07, 2023, 9:30 PM EDT
response: I really was not able to find much more. These fungal leaf spots seem to be common on Nyssa, and a tree in alkaline soil, or with insufficient water, may be more susceptible. I've only found one resource that even lists a specific fungus, and it is quite old (I'm attaching it so you can read it yourself if you're so inclined). The fungus infecting it here in the PNW may well totally different.  You might test the soil pH by both trees to see if perhaps the pH is too high for some reason around the spotty one.

responder: The Question Asker Replied July 07, 2023, 9:38 PM EDT
response: Signe:Thanks so much for rechecking for me; I appreciate your efforts on my behalf. The description of the symptoms sound very similar. I may have to give up on a Nyssa in this location. Thanks again,AlanOn Jul 7, 2023, at 6:30 PM, Ask Extension <<personal data hidden>> wrote: