I think my incense cedars are dying...?

bugchucker · Jul 7, 2009

Hello
I'm having issues with my incense cedars (Libocedrus decurrens). I live in Reno, NV. Until recently it has been cooler and wetter than normal for Reno (60-70 F). For the past 3-4 weeks it has been in the upper 80s to low 90s and very dry.

Both trees were planted about 3 years ago. At the time of planting they were hand watered every couple days. Last September I installed an irrigation system and they now get water daily (5 gal/hr drip, 20 min 3 times/day).

Both trees were planted by the nursery employees. I was given a bottle of “Root Stimulator & Starter Solution” (5% Nitrogen, 15% Phosphate and 5% Potassium, I think, the label is in Spanish). I treated both trees once last summer and once this summer. Both seem to be getting worse rather than better.

The soil here is not great, lots of clay and rocks. The worse of the two was given “tree spikes” last fall.

I can’t think of any other details. Is this rust? Too much water/too little water? Thoughts?

There is a link at the bottom of this thread to my on line web album (my pictures were too large to attach...) no tricks, viruses, or whatever, I promise.

http://picasaweb.google.com/bugchucker/Trees?feat=directlink

Thanks in advance for your assistance!

Phil

windthrown · Jul 7, 2009

Wow, all that work for insence cedars? They grow like weeds in central and south Oregon. No help at all. Dusty roads, mowed over, beaten down, and they still grow. No way to overwater them. Cannot be done. They grow in flood plains. They seem to tolerate droughts as well. They grow (and thrive) in hard pack clay. They seem to be heat resistant. Last place I live in Central Oregon had 8'+ of rain a year, and 100 degree temps in summer and little rain from May thought November. They self sowed all over that palce. They survive in the extremes, and are really an invasive weedy species.

Urban Forester · Jul 7, 2009

Picture #3 seems to show sap loss (?). I noted a build-up of sap at a branch whorl. This may indicate the presence of a flat headed cedar borer (Chrysobothris nixa). Carefully remove the sap "mass" and see if there is any tunneling underneath. In most cases borers are secondary and attack weak/stressed trees. So treatment of the borer is really geared toward bringing the trees out of stress. My guess is that these plants are in transplant plant shock. Most people don't realize that shock can occur for a number of years after planting depending on the size of the tree (rule of thumb- 1 year for every 1 inch of trunk caliper). Root establishment is a tricky thing, especially in soil that is less than great. I would however recommend not using tree spikes or any NPK fertilizer until/unless the plant is established. Fertilizer in a compacted root system can actually increase stress levels by dessicating roots (NPK does contain salt). It also can "trigger" new growth that an under developed root system can't support, thereby increasing stress. If fertilization is used it should be done in cooler weather, spring or fall when the plants are storing energy and not during the summer. I would work in the soil (rhizosphere) by increasing organic matter that is available to the plant. This can be done by using compost in the root zone (carefully, not to disturb the roots) and mulching the same area to improve water retention and regulate soil temps.To say the least, in MOST cases these are hardy plants and once established should do well.

S Mc · Jul 7, 2009

I agree with Urban Forester's rule of thumb on transplant establishment. This is why we recommend people buy 1 to 2" caliper trees rather than much bigger.

However, I would have expected your trees to have settled in by now. Dirr, Manual of Woody Landscape Plants, does mention that Calocedrus decurrens[/] can be difficult to transplant but that once established are very tolerant of soils, heat and drought. He also mentions though that they do NOT like smoggy or wind-swept conditions. Your trees have the fence by them which should help protect them from the Reno winds.

Before you amend the planting bed in the manner UF described (which I also support), dig down to see if you can find any root flare or any indication of burlap or strings left around the trunk. If these trees were ball and burlapped and they left it on but cut it down and away, that is ok. If you find the burlap still around the trunk and 3 to 4" below grade, they are buried too deep and you will need to correct this.

Amending the soil with organic matter and top dressing with mulch will help give the trees the desired "moist, well-drained, fertile soil" that they evidently prefer.

I am also against the fertilizing regimen. The best thing you can do is provide the mulch, as recommended, which will help stabilize moisture retention, provide organic matter to your soil through decomposition, with the added benefits of natural nutrients becoming available during this process.

Sylvia

windthrown · Jul 7, 2009

I have to agree on planting smaller trees. I used to harvest baby trees form the woods and pot them up for a year and then plant them. The smaller ones did better than the larger ones. Also smaller trees tend to catch up to larger trees planted at the same time. We planted tens of thousands of seedling trees on the ranch I lived on in central Oregon. Smaller transplanted trees there always did better.