I have two young Vancouver Jade Arctostaphylos plants, and both have black spots followed by yellowing and leaf loss starting at the base and moving steadily towards the branch tips. The branches are blackened and bark is pealing off. I have Serenade garden biofungicide (Bacillus subtilis) which I am diligent in using and am careful when watering not to splash the plant, and cut off any affected leaves every two to three days. I have been using the spray for about two months now every week but the spots and blackness keep steadily advancing. I had a similar problem last year on a raspberry plant, and tried Green Earth fungicide (Sulphur 0.9%) which also did not help. I ended up cutting the raspberry plant back to the soil last winter, and it came back well this year. Many of my plants last year were also heavily affected with powdery white (mildew?) and I lost a rosemary and had to cut back all of my butterfly weed which is just now bursting back out of the soil. All these plants are in huge pots (15-19" deep) on my balcony. I keep them well spaced, apply occasional fertilizer sticks every couple months and liquid kelp with water once every week or two. It is an East facing balcony. Any ideas what I am doing wrong and how I can save these plants?
Check your soil pH, it should be acidic. These plants can be fussy about their soil and they prefer full sun.
I'll look into getting a soil pH test. Any suggestions on brands or types? You're right, I think the lack of sun has a lot to do with these poor individuals. When we had that short sunny period (summer?) the spots started to decline, and one plant put out some new leaves. Then we had a few cloudy days and suddenly the spots were on the tips of the shoots, instead of progressing from the main stems. I think I will get rid of these plants, they seem beyond saving. I feel bad whenever I have to kill one but there is no more promise of sun this year! I was in denial about my balcony being partly shady, but now I won't try any more sun loving plants. Any good suggestions of local bog plants? I get little sun but lots of rain ^.^
You can get a pH litmus paper kit at places like the home depot or any store with a hot tub section. Look there. It is about fifteen dollars for the package.
