Richard said in CA it spread when trees are dormant which has nothing to do with what you are saying, as far as UC Davis guidelines are concerned. He said that is the time it enters trees while my understanding it that it usually enters though tender new growth, generally in spring (although spring technically comes in winter where Richard lives, but it is biologically spring nevertheless). Tissue in spring is most tender and many diseases are more prevalent then.
Now I’ve learned something, but the questions I now have- does this have anything to do with the diseases spread and how did the bacteria get there in the first place? Does this have any significance at all in the control of the disease or its spread?
Finding some isolated bacteria living within the living tissue of a tree doesn’t mean much by itself. Perhaps it is walled off the way fungus is in trees on a regular basis. The article doesn’t say anything about this being a regular source of inoculum for the diseases spread, does it? Maybe someday that will be discovered to be the case, but is there any evidence of it now?
And do those bacteria eventually multiply and cause symptoms? If so, when?
Without explanations there is no way to know if the discovery of living FB in healthy trees is relevant to controlling fire blight at all. It could be just an irrelevant fun fact- the document is from 1979 (was it even published in a legitimate peer reviewed outlet?) so if that discovery was significant it seems it would have long since made its way into the general literature of how to control FB and its cycle of spread.
The document is almost 50 years old! No corroboration since?
I believe too much nitrogen , either from fertilizer application, compost, or just excessively fertile soil, etc…, is the biggest factor that encourages fire blight . Trees with excessive growth are prone to bad fire blight infection. Conversely, trees with low to moderate nitrogen status are much less susceptible.
I push young trees with nitrogen to get them bigger than a deer can eat for about 3yrs…after that I want to slow them down ,aiming for around , on average 10 inches or less of shoot growth . Seldom get fire blight on trees with low nitrogen status.
I also asked in a reply to you, but I will ask just in case you miss it. Have you tried the Fertilome Fire Blight Spray? Now that I think of it, will treating a tree for FB that doesn’t have FB harm it?
Once it is in the wood, it will not respond to any treatment other than pruning it out. Sprays have to be done preventatively when conditions are ripe for infection. It’s difficult to know for sure whether any given spray application actually prevents anything because symptoms don’t usually present until a couple of weeks after the infection event. And just because conditions were right for infection does not mean there was actually an infection event.
So I understand, your vote is that it’s not FB. And you recommend letting it grow a while longer to see if more symptoms occur? Cankers, oozing, black branches.
I have a Wild Goose plum that I thought was possibly fire blight, but the more I diagnosed I think it may have been caused by either watering causing splashing on the upper limbs, either that or simply heat stress since we are having some record heat days lately. First you might check your local soil conservation service to determine if native soils in your area are low in some of the trace minerals that plants use to uptake nitrogen. That could give you some clues as to what nutrients the plant needs to recover. Then If you have access to an organic soil nutrient that contains most of the trace minerals you could try mixing additional nutrients into the top soil and mulching that with a couple inches of compost. If compost is not available mulch with peat moss. Sometimes new plants need to adjust to new environmental conditions. They tend to suffer transplant shock, maybe when you planted it it was just bad timing. There are many possibilities, but it seems to me the color looks like a nutrient deficiency. So try to treat it for recovery by next spring
Good luck,
Dennis
FB, in my experience, tends to girdle shoots in a way they die completely and suddenly- as if burned by fire. There is often, but not always, an oozing canker at the base of the strike. Whether this is how symptoms always appear, everywhere, I don’t know. The only CA FB I’ve seen was on a Seckel pear in coastal far N. CA. on my sisters property where there is frequent coastal fog adequate for redwoods to thrive. The strikes are always in very small shoots and have never seriously threatened any of her pear trees.
When I grew fruit in S.CA half a century ago I never tried growing pears even though I loved Asian pears back then and have since learned there was once a thriving Bartlett pear industry there (in that climate Bartletts don’t need cross pollination for max production, according to Childers in “Fruit Science”). Treeland didn’t sell them and Stark Bros never sent me a catalogue- I didn’t even know such nurseries existed.
Lost another grafted variety of my 4 in 1 Asian pear to fireblight. Score on this 4 in 1 is fireblight 2 (shinseiki and 20th century /Nijisseiki), Rosdonald 2 (hosui and chojuro). This tree has been a struggle all along. Multiple Asian pears next to it and they are doing fine.
I took off two days to spend time with my son and grandson and come outside to this. No sign of it two days ago Of course it was there, hiding in the wings, smoldering Dasturdly stuff.
how would you treat it?