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[Gary350]

Our Granny Smith apple tree leaves have yellow spots both sides. Is this natural or is this bugs? Apple tree picture shows spots on the apple? I wonder if I need to buy fruit tree spray?

[applestar]

This is almost certainly cedar-apple rust. There is most likely other infected apple or crabapple (or related species like amelanchier/serviceberry/shadbush) as well as cedar/juniper trees that serve as alternating year hosts in the neighborhood.

I have always perceived that the best defense is to choose resistant cultivars, but it does need to be treated when it appears — fungicide. I only have te resistant ones so I don’t do very much — just the milk solution, compost tea, and maybe baking soda or potassium bicarbonate mixture. But next step up is Copper/Bordeaux mixture I think?

There are of course more potent treatments for conventional care... let’s see

Here we go —

Plant Diseases Cedar Apple Rust | TN Extension
https://ag.tennessee.edu/EPP/Extension% ... 20Rust.pdf

[Gary350]

applestar, thanks for that information. I wish I had known about Cedar Apple Rust before I bought this tree, I would have bought something different. I mixed, 1 T water with, 1/2 tsp baking soda, 1 drop dish shop then painted 3 leaves with the mixture to see what happens. I mixed, 1 T water, 1/4 tsp copper sulfate, 1 drop dish soap, painted 3 other leaves with the mixture to see what happens. I'm not sure how often to paint the leaves, maybe 2 times a day, maybe sun rise & sun set for a few days. I know vinegar is very good at killing fungus I have sprayed tomato plants with vinegar to kill blight, wait a few minutes then rinse away vinegar. I tried vinegar on 1 apple tree leaf. I don't want to kill more tree leaves than I need to, to learn what works.

[Gary350]

Tomorrow I go see if I can buy Immunox fungicide in a spray bottle.

[Gary350]

Everyone in town sells the same products. 1 product for cedar apple rust is 10% copper octanoate + soap. Another product is 7% copper sulfate + soap. Instructions say, max mixture is 1 gallon to 100 gallons. Math works out to 10% of the Copper Fungicide bottle mixed with 1 5/8 gallons of water. Instructions say, spray once very 7 to 10 days. It is probably not good to spray tree in this 93° hot sun I will wait until almost dark to spray this on the apple tree. I have an empty windex bottle spray almost looks like windex.

Sense this makes 12 gallons I can stray it on tomatoes too for blight. Once tomatoes have blight there is no killing it so I should probably start spraying now before tomato plants have blight. OH wait I better read instructions again before I put this on tomatoes???

LINK also says a product that triggers plants immune response will work. 98% Bacllius amyloliquefaciens strain D747. I wonder how safe this is I hate putting unknown chemicals in the garden?

[Gary350]

There was 100s of tiny ants on all the apple tree leaves. Each ants was parked on a yellow spot sucking or eating or what ever ants do to each spot. After spraying copper sulfate water on the leaves all ants are gone. Ants have never been a problem in my garden they eat micro small bug eggs before they hatch. I hate it ants are gone, yellow spots are not gone yet. I only sprayed top side of leaves, maybe this evening I spray bottom side of leaves. Maybe spots slowly go away?

[applestar]

Definitely spray the underside of the leaves.

The spots won’t go away if they are cedar Apple rust, but they hopefully WON’T develop into the next stage which is a puckered raised bump above with orange filaments growing from underneath the leaves to spread their spores.

Where you can afford to lose them, pull off the leaves and burn them. Sterilize your cutting tools and hands, too. Apple should be in hyper growth mode by now so you will have more new leaves That hopefully won’t be infected.