Manzanita - diseases?

My manzanitas don't seem to be doing too well - one has black/brown tips on the leaves and one has some black spots. Should I prune heavily (I might have to take out most of the bush)? Spray with something?

Did this just show up?
This January has been drier than any on record. Plants that are accustomed to winter water can be stressed by the really dry conditions. The browning leaves suggest that sort of thing.

The black speckling might be something else. Here is one idea:
When aphids, scale and a few other insects feed on plants a fungus called sooty mold feeds on the waste from the insects. The waste is basically sugar-water with a few minerals. The sooty mold fungus may sheet the leaves and twigs, or grow in more patchy areas.
If this is what is going on, I would do this:
Look for the pest. Aphids and scale are not very common on Manzanita (Arctostaphyllos sp.) but might also be living in plants growing above the manzanita. The waste would drip down onto the manzanita, so the fungus would grow there.


There are other possibilities. Examine the plant really closely at different times of the day and see if there is some pest that might be spending part of its time on the plant, and part of the time hidden somewhere.

The brown tips started after some utilities people trimmed it back to get to a box, but seems to have gotten worse over time. The bush will shoot out new nice green leaves but they eventually get the brown tips as well.

The speckled manzanita is under a lilac, so the sugar water explanation makes sense. Haven't noticed any critters but will take a closer look. Do you have to remove the leaves that already have the fungus or can it be sprayed down/washed off?

If it is sooty mold from the sugar water excretions of insects it is stuck pretty well, but a strong jet of water ought to wash it off, or you can make a mild solution of dish soap and spray that on, then blast it off.
Sooty mold ought to wipe off, but there is no way anyone would want to take all the time to wipe off each leaf!

If most of it does not come off with a blast of water there may be something else going on.

Native plants are used to getting their water in the winter. In dry years it would be beneficial to deep soak them about once a month November through April (Pretty much our normal rainy season).
If the storm that is supposed to hit us this weekend does not give you at least an inch of rain, then I would sure take a hose out there. If you need to, build a bit of a trench and berm around the plant to hold some water out around the drip line of the the plant until it soaks in.

Judging from the die back on the leaves in the second photo it's possible your plant got infected with some kind of blight when the utility people cut it back, or it might be Phytophthora ramorum. Neither of these diseases have a guaranteed cure. If it's a blight, you can try cutting it back, sterilizing your shears between each cut, and see if that helps. If it's P. ramorum, there isn't any cure except taking the plant out and starting again.

The Manzanita in our neighborhood are also dying back and suffering. My neighbor lost her large mature plants on her back slope. (Very little water, slope drainage, south facing, Encinitas). She says hers looked exactly like mine (see photos). Looking closely, I do see insects and even webs on mine (not evident on photos of pephemie's). I am trying Neem oil today and making sure I get all sides of leaves. Possible the insects are attacking a plant weak from disease. Does look exactly like leaf scorch I see on Oleanders. I will also be pruning off dead growth while cleaning pruners between cuts. Diluted bleach or alcohol?

Bleach or Lysol
Thoroughly wash and oil the pruners when you are done, these materials are not kind to the pruners.