Avocado help needed.

[9B in Brazil]

I had a 10 y/o avocado quickly die from what appears to be root rot.  Given my heavy rainfall and humidity, it's no surprise.  Are there specific rootstocks known to resist this.  Unfortunately, I have a lot of clay soil with lots of moisture.  I can amend the soil when the trees are young, but the roots will eventually find the clay as they get older.  Also, which varieties would do best in my climate?  Thanks for your help in advance.

[spaugh]

there are clonal root stocks for sale in CA that are supposed to be more tolerant to Phytophthora cinnamomi (root rot).  However from the reading I have done on this, they are not that much better.  Nothing is root rot proof in other words. 

To help with the root rot, you want to mulch heavily on top of the soil with woody tree trimmer mulch.  The worms will move the organic matter down for you and help ammend the soil.  Plant the trees on a hillside or on a tall mound and put a foot of mulch on top of that.  And keep the root ball high relative to the ground level.  Do not make a trough or basin around the tree except for the mulch itself.  Keep the mulch several inches away from the trunk of the tree.  If you keep the tree up high, excess water will drain away.

[9B in Brazil]

Thanks Spaugh for your suggestion.  So, rootstock may not be my issue; and selective location and mulching is the best way to prevent root rot (from Phytophthora cinnamomi)?

[fruitlovers]

There have been rootstock selected for root rot resistance, but they are very difficult to obtain, especially in Brazil. What i suggest you do is find an old avocado in your area that is thriving and use that as the rootstock. Also as already has been suggested, plant the tree up on a mound. I also incorporate a lot of material that drains very well. Here we use cinder, but a lot of sand mixed in would also work well.

[9B in Brazil]

Thanks Oscar.  As my rainfall is like the Hilo side, what cultivars do best there?  Also, I did finally get my books from Instituto Plantarum.  Thanks for your help.

[FrankDrebinOfFruits]

[...]I also incorporate a lot of material that drains very well. Here we use cinder, but a lot of sand mixed in would also work well.

As soon as I changed to doing this, my avo trees started thriving in clay.

[9B in Brazil]

Thanks Frank.  What part of Kauai are you?  I lived in Kilauea for several years.  Any suggestion of which varieties do best in higher rainfall areas?

[FrankDrebinOfFruits]

Thanks Frank.  What part of Kauai are you?  I lived in Kilauea for several years.  Any suggestion of which varieties do best in higher rainfall areas?

I am in Kapaa. I have only 3 or 4 years experience in growing avocados. Give me another 10 years and I will have a more formed opinion

[9B in Brazil]

I understand completely.  It is for this reason I am looking to increase my chances of picking a cultivar that works in my environment.  I'd hate to plant some avocados that won't do well here, and waiting 5 years just to see if I made a good choice, doesn't seem prudent.  For this reason, I'm hoping someone can share some of their knowledge and point me in the right direction.

[StPeteMango]

I killed three avocado trees before trying a raised bed. The avos are now two years old, and thriving.
The first three trees were planted on level ground, and there was no visible flooding. But the summer rain, I guess, saturated the soil enough to cause root rot.
The raised bed is 4 feet x 4 feet, and a foot high. But I also piled up some soil, raising the level a bit more above grade. Also piled a lot of mulch to support the raised bed - the mulch is about 2 feet deep, and extends 5 feet beyond the trunk. No mulch within 1 foot of the trunk.

[9B in Brazil]

StPeteMango, so you have a raised bed with 1 foot of soil and on top of that 2 feet of mulch?

[StPeteMango]

Around the raised bed, and to some extent within it as well. The sides of the bed are 4 feet x 4 feet. The mulch starts about a foot from the trunk. It is piled higher than the raised bed, extends out a couple of feet beyond it. Can't even see that there's a raised bed. Attaching a photo of how it started out two years ago. The mulch pile is just past the black PVC ring. To show how it is now, I'll take and post a pic tomorrow when there's light.
http://postimg.cc/image/wls59prxl/

[StPeteMango]

This photo was taken minutes ago, shows the mulch piled around the raised bed for the avocado:

[9B in Brazil]

I see.  Thanks for the pictures.  They really help.  I will try this for sure.

[FrankDrebinOfFruits]

As I browsed through the trees yesterday it occurred to me, sometimes there is a lack of local advice and/or the local advice is not the best.

For example, most of the avocado varieties pushed by the local nursery haven't fruited for me. As well as some Florida varieties.  The varieties that the local nursery advised won't do well are actually doing the best.  For example, I was told Hass doesn't do well here, but it's been easily the most prolific of all (with 4x more fruit than the next closest variety).  Other notes Lamb Hass, Holiday, and Ota have also done quite well. Holiday is pushed locally. 

If I was to do it again (on a larger scale), I would set up a test area planting at 7x7 ft spacing and find what fruits/when over a period of 5 years, then plant that variety out or top work an existing field. Or plant out a variety of trees and just plan to just top work the entire field. 

[9B in Brazil]

I had 7 trees in Kilauea, and the Hass was the best producer for me also.  I will try that one with Sir Prize to cross pollinate.

[spaugh]

As I browsed through the trees yesterday it occurred to me, sometimes there is a lack of local advice and/or the local advice is not the best.

For example, most of the avocado varieties pushed by the local nursery haven't fruited for me. As well as some Florida varieties.  The varieties that the local nursery advised won't do well are actually doing the best.  For example, I was told Hass doesn't do well here, but it's been easily the most prolific of all (with 4x more fruit than the next closest variety).  Other notes Lamb Hass, Holiday, and Ota have also done quite well. Holiday is pushed locally. 

If I was to do it again (on a larger scale), I would set up a test area planting at 7x7 ft spacing and find what fruits/when over a period of 5 years, then plant that variety out or top work an existing field. Or plant out a variety of trees and just plan to just top work the entire field.

How is fuerte doing for you?  It seems to be a beast like hass for me also.

[fruitlovers]

Thanks Oscar.  As my rainfall is like the Hilo side, what cultivars do best there?  Also, I did finally get my books from Instituto Plantarum.  Thanks for your help.

Some that are doing well and producing well: Linda, Yamagata, Semil 34, Murashige. Some not doing so well: Sharwill, Green Gold.
Glad you got your books.

[Mike T]

 If the rainfall is more than say 2500mm/yr and you are tropical but want a Guatemalan avo with reasonable resistance then shepard and reed are probably best. Rootstocks used for anthracnose resistance like plowman, nabal.reed and velvick seem to have good phytopthera resistance as well even on clay.

[zands]

There have been rootstock selected for root rot resistance, but they are very difficult to obtain, especially in Brazil. What i suggest you do is find an old avocado in your area that is thriving and use that as the rootstock. Also as already has been suggested, plant the tree up on a mound. I also incorporate a lot of material that drains very well. Here we use cinder, but a lot of sand mixed in would also work well.

How about he gets seeds from this old master avocado tree and plant them right where he wants his tree to located after amending the soil, making a mound etc. Then  top graft scions from the same old tree? IOW make a reproduction of the old tree.

[Avinsmith]

Need to plant equal or higher as ground. Did a row to flowing water