I grow several Asian pear trees. Over the past few years, I always had some problem like rust. The baby fruits (soybean to fava bean size) would mal-form, drop. Some were coated with orange color powder. This affected yield.
I also grow some apple trees. The leaves had some rust, then some fell. My mayhaw were also impacted. Not sure if the leaf rust is related to the Asian pear fruit rust.
I do have a large property and we have a lot of red cedars. I’m not sure if this is cedar rust.
So I’m thinking about some kind of fruit spray to control the rust. Not sure if sulfur type is good, or something like Surround.
I’ve seen the same type of thing on some of my Asian pears, but usually not enough to be a problem for my yields since I have to thin them quite a bit anyway to get decent sized fruit. My flowering quinces and the juneberries I used to grow before I removed them got hit very hard by this kind of rust to the point that all the fruit are infected unless sprayed. Immunox works well on cedar apple rust and probably on any related rusts also.
It looks somehow like that. We have a lot of wild red cedar. I’ve cut down like 30 of them. They harbor diseases on my blackberry, possibly apple rust and pear rust.
My Asian pears are in the middle of blooms. Not sure if this is a good time to spray. Or too late? I think the article says to spray the cedar? That is going to be hard since they are in the dense woods and there are still plenty.
During bloom is when the spraying is supposed to be done, yet where there are blooms on the cedars (spraying the cedars), their leaves and their flowers both. I myself have not had this problem and so I have no personal experience dealing with the disease, so I have not tested any possible solutions to it. It sounds to me like the best way to prevent any damage to the pear fruit is to keep as much of the fungus away from the pear flowers as possible, and of course to have resistant varieties of pears, that lessons the problem many years for fungal diseases that can effect pear trees in general.
I have been cutting down those red cedars over the past few years. There are still quite many within about 100’. They readily seed in open field.
The Asian pears have started to bloom. Is it good to spray now and during blooming? I recall it may affect pollination and the bees. The wild pear trees are in full bloom now. We have a lot of those too in the woods.
“Bacillus subtilis (sold commercially as Serenade® Garden Disease Control)” is suggested to spray after exposure to rust, and supposedly it does not harm the bees.
What @mamuang suggested is recommended for what you have at “every 7-10 days during the period of infection” yet it does harm bees. The every 7-10 days is for ‘Spectracide Immunox Multi-Purpose Fungicide’
Also copper can be used “You can treat them with a solution of copper at least four times. Use 0.5 to 2.0 ounces of copper per gallon of water.” Yet copper is mainly a prevention, it does not do anything when there is already a rust contamination on the pear trees.
Speaking of wild pear trees, I was reading that some ‘Wild callery’ can carry and help spread the disease.
There are two cherry trees on the front behind driveway. Asian pear trees are further to the left, but about 15’ away from the cherry trees and the woods.
The area behind the fruit trees is like 3 acres. There are red cedar on the front, and various other seedlings like wild pear, red oak, hickory, black walnut, black cherry and many others. The tall trees far behind are red oak, black walnut and hickory. I think those cherry trees are about 30’ to the woods. So the pears are about 50’ to the woods. Far closer than I originally thought.
Serenade does not control rusts. Myclobutanil only requires one spray after petal fall, not every 7-10 days. Copper also doesn’t work. I battled rusts for ten years without myclobutanil and gave up a few years ago, now I do my annual spray.