Question
Hi,

We live in SoCal and I planted five trees earlier this year: two grapefruit, one pomegranate and two avocado. All were 5 gallon and all but one of the avocado went in the front of the house in an area that used to be planted with juniper bushes. The pom and both grapefruit are doing really well and the avocado that's planted in the back of the house is doing okay. But the avocado in the front slowly had all of its leaves go brown from the tip up and then fall off completely. It had some new growth in May, but by June the same thing had happened a second time and there has been no new growth since. (Well, there was a tiny bud at the base of the trunk, which put out two tiny leaves, which also browned and fell off earlier this week.) I know the soil didn't drain well enough and I'm guessing that it was just an inappropriate place to plant that tree (since it didn't get much more water than the one in back). From everything I've read, I have to guess it got root rot. Does that sound right?

If so, my questions are: 1) Is root rot something that can be overcome at this stage? Its trunk is still very healthy looking (I painted it to protect it from sun scorch and I can see the healthy green in the unpainted areas) but I don't know if it's a lost cause at this point and I don't understand why the whole thing isn't just dying. 2) If it IS a lost cause, is the soil under/around it contaminated permanently? Can I plant something else there? Would another citrus type or pom be more resistant to contaminated soil? 3) If it's not a lost cause, could I uproot it and replant it in the more sandy soil we have in our backyard? It's really hot here now, so would replanting it in 100 degree weather kill it the rest of the way? I know I can just buy another avocado tree next year, but I have put so much time and effort into that tree, I just want it to heal itself. :)

Thanks!
Megan

Answer
Hi Megan:
From your description of the symptoms, I expect the tree has been severely stressed and the long term prognosis may be quite dim for this tree.  Many of the soil microorganisms that can cause root rot can either survive for extended periods in the soil or they are common inhabitants.  So, we end up putting our plants into situations that can bring on stress.  The goal is to create good environmental conditions for the plant , but unfavorable for the disease organisms that are probably already in the soil. Drainage and soil moisture need to be addressed for our plants.  Ideally, the soil needs to drain good.  Poorly drained soils are the ideal environmental conditions for several root rot organisms like Pythium and Phytophthora. These organisms wait in the soil for the plant to get stressed, then they become a real problem, so with that said, your trees need to go into an area that does not hold water for extended periods in the soil. If plants are planted into "contamined" soil, special attention needs to be paid to water issues and drainage.  Some plants are indeed more resistant/tolerant to these organisms. Our goal as plant "custodians" is to provide good conditions for the plant- things like appropriate drainage, good nutrition, moisture etc.  It is always a good idea to have a soil test done first- to be sure the plant has all of the nutrients its needs.  Consider contacting your local county Agricultural Extension Service ofice to arrange for this plus other services, including an exam of your plants to determine if it is indeed a root rot disease or something else. The services are usually free.

Regards
Steve