Hi Carla,

If it is in the system way deep down in the main trunk, it is too late now.

I have not sprayed anything on my apples and I've got only very few fireblight. I snip off 2 ft below the area the first sign of subtle wilting, that way it is manageable but it would automatically chop off the tree if it was younger.

Anyway, not to worry about even if you lose the whole tree, i have a collection of many proven fireblight tolerant apples in our area. I live in Davis, the fireblight capital of the world!, at least that is what seems to be like. So if ever you needed some fireblight cultivars, I'm just the next city away and we can graft those over your tree. Be sure to have fireblight tolerant rootstock, otherwise it will be useless.

Many apples and pears respond differently to fireblight infection as a manifestation of their tolerance or resistance. Some for example the Jonagold, manifests its resistance by wilting the flowers rapidly and let them fall off, so the infection doesn't spread to the trunk, only the spurs are dead but the rest of the tree is okay. Some pears like Kieffer managed to live through the infection and bear fruits. Some cultivars would bloom out of sync, in the middle of hotter weather, so they escape the fireblight, and it is really an avoidance mechanism rather than tolerance because if they happen to bloom at the time when it has just rained and the temperature is between 70 to 80 deg F, then everyone that's in bloom will almost get a hit.

I bought fireblight streptomycin spray from Bonide, yes it worked, but it is too expensive that I'd rather live with somewhat fireblight tolerant apples, some of them could be tasty too, like the Honey Crisp, Monark, Winesap, Goldrush, Macoun.

Most of the ultradwarfing rootstocks will increase tolerance to fireblight because of slower growth. Fireblight loves vigorously growing young trees. Home Depot sells several of these ultradwrfing apples and pears and in my yard, those were never hit with fireblight, perhaps a few times but their spurs fall off and never get the stems infected.

Next approach would be to spray with copper sulfate or kocide directly on the blooms after each rain during spring time, and every three days thereafter until the bloom is over or the temperature exceeds 85 deg F.

Couple that with applying fertilizers that are very low in Nitrogen but very high in P and K, like the 6-20-20 lawn starter fertilizers. Your apples would be precocious bloomer but very slow growers. Slow growing trees, the fireblight don't like much.