Leyland Cypress can take hot weather, but only in a limited way - it leaves them highly susceptible to Seiridium cardinale canker disease, and they rarely survive more than 10 years or so in central California. Possible the plants may have become infected at the nursery, or soon after delivery.

You'd do better to use one of the California native cypresses, such as Sargent Cypress, which is more resistant to Seiridium canker.

Resin

PS Leyland

Thank you for the info, I'd better get rid of the 2 dead ones before others are infected.

Upon closer inspection, other trees are infected as well, but they're are still green. Is there ANYTHING I can do to save those remaining trees? I'm not sure if the fungus is the same type that you said, please see the photos. Thanks,

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Removing the dead would be a good idea. My wife has a row of them planted at 6' apart. Within 4 years they had completely closed this gap, that is also about the time the bagworms started. 6' was way too close together. 12' would be a better distance. These trees seem to be either growing or dieing and are high maintenance trees. I am currently climbing ladders to remove bagworm/remove dead limbs/etc and their drought resistance appears to be nominal. Eventually they will get too tall or I will be too old. I have reached the point where I prefer low maintenance trees, which sends one back to more native varieties as suggested above. Drought resistant/low maintenance Arizona Cypress or Eastern Red Cedar have worked well here in Tx. In California, you have several native conifers to choose from. Good luck.

I'd strongly suspect the disease is far enough progressed that they were infected before they left the nursery. Try to see if you can get a reclaim on them.

Resin

Not my area of expertise, but those sure look like mealybugs to me (you can see their ovoid shapes and antennae in a few spots). Once established, I think they are very hard to get rid of...

I would suggest ridding yourself of them and planting one of the native species of California Cypress that are adapted to hot and dry climates such as Tecate Cypress, Sargent Cypress, Macnab Cypress, or Cuyamaca Cypress. Tecate is probably the fastest growing and can be purchased from Las Pilitas Nursery via mailorder, or as seedlings from University of Idaho Nursery at 2 dollars each. Call Annette at 1-208-885-3888

OK I'm in the process of removing the 2 dead Lelands. Are you guys saying that the remaining 5 trees, that have the white infection on the trunks and branches, are beyond saving, even though they're still green? I will remove them all if this is the case. I just want to find out if I can scrape the white stuff off the 5 green trees and use some fungicide, will allow them to recover.

Thanks,

newgen,
I'm not an expert but from what I've seen and read, the Leylands appear to be a high maintenance species in many parts of this country. Even if you had success this year, the same or other problems will likely show up next year, and the year after, and so on.
That said you already have the trees planted and its not a good time right now to plant other trees, why not experiment a little and see if you can perhaps save them for a while.

scotjute: That's exactly what I'm thinking. Avoid having to dig up 5 other trees,when there's a small chance they can survive for a while more (even a few months is worth it to me). This gives me time to research for their replacement (I may go with something else entirely) and tend to the rest of my yard. Also like you said, it's too hot to be digging and planting. Thanks,

The white stuff on my trees don't look too much like the photos here: http://edis.ifas.ufl.edu/fr341

So maybe it's not Seiridium cardinale. The white stuff feels mushy, kinda like mealybugs, like wassercom posted above, and there are ants all over them.

If you look at the big mass of white stuff in your first pic, at the 10 O'Clock position, you can see one of them crawling away.

I've had them with indoor tropicals before; they're pernicious.

I got rid of the 2 dead trees. I crushed and wiped off as much as I could those white masses of mealybugs on the other 5 trees. Tomorrow I will do this: http://www.ehow.com/how_5075401_kill-mealybugs.html

Update: I mixed full strength rubbing alcohol with a good amount of dishwashing soap, sprayed all over the mealybugs colonies, I immediately saw them shriveling up and died. As of now, there are no more of these nasty bugs on my remaining 5 trees. My last spray was over 2 weeks ago. All branches are healthy now.