Random deaths of Grevillea Longistyla

I have about a dozen Grevillea longistyla planted in the same area. They are mostly healthy but very slow to take off. They've been in about 2 years or more now and every now and again one or other will start to yellow and die. There doesn't seem to any particular pattern - it's not that 2 close together, or approximately the same age or anything are affected. Sometimes it's a replacement planting that dies young, other times a healthy survivor. I've given up replanting but would like to try to save the ones that are left. Does anyone have any ideas about what could be happening here?

Not an expert on natives, but it does sound like there is something they don't like there. It may be something in the ground .
I would check the soil where the dead ones were. I know I have lost plants when there has been old concrete in the soil. I have had a few plants just start going brown on the branches and dying. There seemed to be no cause and no problem with the plants right next to them.
If it were a virus or such, you would probably see them all dying.
Someone on here is sure to have some info for you.
Jean.

G'Day
If your Grevilleas are dying from the bottom up I.E. roots first then suspect a soil born disease. A lot of Grevilleas are very susceptible to root rotting fungi. If this is the case you could try a drench of "Foliafos", which is reasonably cheap or Ridomil. Most Grevilleas need good drainage make sure that some plants are not getting more water than others (Run off). If your plants die from the top back the problem could be Fungal, Viral or Bacterial. The best way to manage this is to cut off affected limbs and burn, make sure you cut far enough back so you see good clean green wood, not discoloured as this indicates the disease is already that far back on that limb. The other thing that is of no use to you and that is that Grevilleas, in fact Proteacae generally are prone to just up and die for no apparent reason. Although there must be a reason it is just not obvious.
Brian

Hi Jane,
What soil type? As Stake mentioned drainage is a big factor with these plants. If sandy then it should not be an issue. If clay then you may have problems. I have seen a row of Callistemon suffering the same fate. Some of the plants on the row were dying. It was clay soil and when I scraped off the mulch it revealed perfectly rounded planting holes. He had used a post hole drill which left a lovely hard basin to hold the water.
Hope you find the answer.
Steve

It's an interesting thing about natives Brian. As you say, they can just up and die.
I had 3 golden wattles in a row. They grew for about 3 years then one started dying branch by branch. You would have thought it had been sprayed or burnt. It took a while but it did die. A year or so later the next one started and took about 8 months to die. By this time they were all around 8' high. It has been over 2 years now and the last one is around 15' high and very healthy.
Very odd. I had a couple of hebes do the same thing and a protea that has been healthy for over 12 years had just one branch die piece by piece. Plants are great for giving us mysteries.
I do hope you save the rest of your Grevilleas, Jane.
Unlike most plants. natives hate being moved so cross your fingers it was random and won't affect the others.
Jean

Thank you all for your time and thoughts. There are two currently looking dodgy and I'll let you know what happens

I've been giving Iron Chelates to the two latest sickly looking plants and it seems to have arrested the problem. So far so good