Rainfall probably inadequate. Amending of planting hole backfill undesirable, it affects how water moves into and out of planting holes so treated. Under dry conditions an unamended soil will often have a greater attraction for water than the coarser textured amended backfill, resulting in chronic dryness within the planting hole. For the same reason intact potting soil rootballs are apt to shed water to surrounding soil. You have to water so as to make up for this until newly planted stock roots into the unmodified soil beyond the potting soil rootball. If the planting hole backfill has been amended the plants may have to get into the unaltered soil beyond the planting hole before they are out of danger. Plants sufficiently damaged by poor moisture conditions within the amended planting hole may be slow to root out of it, or even die. Otherwise rooting into natural soil beyond planting hole often quick - within the first year after planting - after which top growth picks up nicely, creating the false impression that amending of the planting hole backfill produced a good result. Rocks cool the soil the same as organic mulch, it is the shading that is the main benefit as far as improving moisture conditions within the soil is concerned.

"cut worms" are not common issues with any woody plants. These are pests that attack seedlings primarily and at ground level (not below ground). I would be very skeptical of any cut worm creating this sort of rapid decline/fatal damage to an established pitt. There can be other organisms that can cause problems, however. A root knot nematode is thought to be responsible for widespread crop failures of pitts in southeastern climates but I am not sure how populous these creatures are in CA soils. I would be inclined to take/send a diseased/dead sample - roots and some soil intact - to your local extension office or plant pathology lab for diagnosis. If root knot nematodes are determined to be the problem, there are biocontrols available, including applications of beneficial nematodes. I would also not dismiss a root rot of some sort, as mentioned above. Pitts can be prone to a number of these pathogens and they are far more likely to cause that very rapid decline and death than just about any other issue.

Around here pittosporums (along with photinias) are very popular for privacy hedges.The only negative thing I'd previously heard was that P. Green Pillar is prone to mealy bugs. We have one (planted before we knew) and it had an infestation one year, which didn't seem to slow it down any. I wish I could remember what variety the troublesome pittosporum is. When I remove the dead branches it looks reasonably good. It isn't drying out all around the edges as if it's a straightforward watering problem. It's not growing as fast as the older one but the older one got a good start long before the drought. I think I'll see what happens this autumn. I need privacy for a bedroom window in a hurry so I'm really torn between persevering with a shrub that should be tall enough in another year or two or starting again. If I started again I was thinking of P. Screenmaster. Anyone have any longer term experience with that one? I was also thinking of planting a fast growing wattle in front to give privacy until the shrub catches up but I was worried that the extra shade would slow down its growth. Decisions, decisions. Any suggestions for a dense fast-growing shrub to 4m that doesn't mind clay soil and drought and a temperature range of about -7 to 40 and doesn't have stinky photinia-like flowers. I'm not asking too much am I?

There have been numerous reports on these forums concerning this issue, most arising from California. Pitts are very prone to root rots and the recent prolonged and heavy rains in that area may be contributing to the problem. Beyond that, you haven't given us much to go on.........:-))