Multiple rootstock tech as disease treatment

[shaneatwell]

Simon posted this a while ago and I'm curious if there are documented examples of multiple rootstock technology being used to treat or prevent disease, especially in citrus or avocado?

Thanks for all the information.  The repots on interplanting with Guava is really interesting.  Too bad I still can't find a place that sells Seedless Vietnamese Guava, they are extremely delicious.  I will be picking up a few pherimone traps to protect my citrus.  The research regarding Genetically modified citrus with the Spinach gene looks promising.  I remember reading somewhere that there was some sort of ailment killing many citrus trees and trees were eventually saved by multiple rootstock technology.  The additional rootstock added to existing trees were resistant to whatever disease or ailment was affecting the fruitcrop tree. 
Simon

[shaneatwell]

I think I found it.

http://www.citrolima.com.br/bulletin/bulletin3b.htm

MULTIPLE ROOTSTOCKS    The practice of grafting additional rootstocks to a tree is called inarching and was developed hundreds of years ago to give plants longevity.  Its commercial utilization in large scale was pioneered by Brazilian citrus growers to prevent tree losses caused by the disease Citrus Sudden Death. Citrolima nursery trees now have 2 rootstocks as a standard. The objective is to maintain the excellent qualities of our most common rootstock, Rangpur lime ( broad soil adaptability, rapid initial development, drought resistance, early bearing and high productivity), combined with disease resistance (foot rot, nematodes, blight, sudden death) of another rootstock like Swingle citrumelo. Inarching of additional rootstocks is utilized in some areas of the world to attain more vigorous and long living fruit trees. Citrus trees with 2 rootstocks survive Citrus Sudden Death even on the susceptible rootstock Rangpur lime. There are orange trees over 100 years old that lived through foot rot and who knows what else by the use of the multiple rootstocks technique. The best timing for adding a second rootstock is during the nursery tree stage. Costs are lower and successful rates higher. Citrolima developed special techniques that allow for the addition of a second rootstock to its citrus nursery trees efficiently and economically.

[socal10b]

I added additional 2 rootstocks to my young sharwil avocado, my purpose was to make it grow, it seems to be working ever since i added them, sharwil has pushed out a lot of grow. Now its at dormant stage. Going to flower this year is still up in the air.

[shaneatwell]

What variety rootstocks did you add? I've got a hass seedling and a lamb hass seedling growing next to my hass tree i'll inarch next summer.

[socal10b]

There were fuerte rootstocks. It definitely helps the growth. I think I damaged unknown sharwil rootstock with gromulch when I first planted it, gromulch is a big nono it has a lot of salt, my lamb had almost got killed. I should have replant my sharwil with native soil just like my lamb.

[simon_grow]

Hey Shane,

I've definitely read of people using multiple rootstocks to combat pests or disease in citrus but I have not tried it myself for citrus nor avocado. I believe multiple rootstocking Avocado with the right varieties can have many benefits. Avocado can be killed by Phytopthora and I have read that certain clinal rootstocks are resistant to this pathogen. Certain varieties of avocado can also be very sensitive to high salt concentrations and again, I've read that certain varieties are more tolerant of salt.

Just because certain varieties are resistant to this or that does not necessarily mean that multiple rootstocking these varieties onto suceptable varieties will impart the beneficial attribute but based on what I read regarding citrus, there is definitely a possibility.

Multiple rootstocking also has, from what I have read, the added benefit of increasing precocity, decreasing or eliminating alternate bearing and dwarfing the tree. This last benefit requires more research in order to understand and verify its authenticity. Perhaps it dwarfs certain trees while increasing the size of others. If anyone has any information regarding this point, I would love to learn. It seems counter intuitive to me but if the dwarfing effect is true, it will be a wonderful thing for people with small backyards like mine.

Dwarfing a tree along with increased precocity and the elimination of alternate bearing combined with heavier yields will have a drastic economic benefit for commercial agriculture. Dwarf trees means a decrease in the cost of labor for pruning the trees and the fruit may also be easier to pick. Having multiple rootstocks can mean faster establishment of trees and a much faster return on investment for the grower.

Someone on this forum mentioned a simple way of natural innarching by planting two seeds right next to each other. They will naturally grow into each other and innarch.
Simon