Fungus on my shrubs?

Question

So after living in our house for 3 years there's something going on with our shrubs. In a previous post you can see the shrubs when we moved in.

However now there are certain portions of the shrub that are not growing any more and the leaves have a white discoloration on them. (see pics) Is there any way to treat them (ideally I'd like a non-toxic solution)?

Thanks!

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Edits

Thanks Everyone for the posts. So here's the answers to the questions. I live in San Diego, CA so the climate is pretty mild here. The white discoloration cannot be rubbed off and the interesting thing is that there doesn't seem to be discoloration on the backside of the leaves only the side facing the sun.

I think may be the next thing to try is the fertilizer as recommended.

Answer 1

If you examined the woody stems and can't find any shield shaped bumps attached to them, nor any other confirmatory evidence of scale insect, then I think this is a bad case of greenhouse thrips. The other possibility is lacebug, but the appearance of the leaves is strongly reminiscent of greenhouse (and other types of) thrips, though lacebug may be present too. If your weather was very hot this summer, greenhouse thrips would have thrived; it tends to attack mature leaves rather than new growth. It does not kill the plant (you can already see new growth at the top of branches which is unmarked) and usually, new growth is produced in spring on older stems if/when the old growth drops off, but it may be necessary to prune back to encourage new growth. Some control with oil based sprays such as neem is achievable, but monitoring during late spring and summer is a good idea to keep them in check by spraying when necessary. Further info here http://ipm.ucanr.edu/PMG/PESTNOTES/pn7429.html.

Keep your plants well watered during hot weather, as well as fertilising periodically during the growing season (but do not fertilize during late fall or winter).

For interest's sake, this link http://ipm.ucanr.edu/PMG/GARDEN/PLANTS/photinia.html lists all the problems Photinia are likely to experience, though it does not describe ways of dealing with them.

Answer 2

This looks like a plant disease that has caused portions of the leaf to die, I suspect due to long term nutrient deficiency (nitrogen, potassium, phosphate).

Plants will sometimes sacrifice leaves in desperation to grow its fruit and seeds if it lacks enough nutrients.

3 years is a long time without any fertiliser for the plants.

Lack of nutrition leads to a weaker immune system.

You will need to remove the dead leaves as they are not helping your plants. Make sure you leave the un diseased new shoots and leaves intact to allow further growth.

And choose a simple fish emulsion fertiliser ask for (NPK 5-1-1) as it will have 5 nitrogen 1 potassium 1 phosphate which will be a safe dose when diluted with clean water.

mix a small amount of the fertiliser with clean water (1spoon per litre) and feed the plants by pouring it around the base but not on it. Do this for each plant once a month at first to avoid overdose as we still don't know the exact requirements of this plant. For that reason I'm suggesting a light dose to begin with, you will be surprised just how little a plant needs to maintain its size and health. Only do this during the growing season of that plant, Plants will not require any feeding during their dormant period(usually when its colder around winter).

Caution as it smells like bad fish so do avoid getting it on your skin.

Feed your plants. especially during their growing season, at the very least once a year.

If that does not help then it could be something beyond my experience.

As mentioned by @bamboo, do check for insect infestation as they would be treated differently by using very diluted neem oil. Simply mix a drop per 1 litre of water and spray all over the plant Caution as it also smells bad like rotten garlic!

Nutrient deficiency could be due to many factors, one of which is nutrition lock out due to wrong PH from tap water but in this case from what you have said and from what I can see the soil seams to be poor in basic/essential plant nutrients.