Arizonans -- what is the problem there? I would have thought cold winter temps (in at least part of the state). But what's up with the rootstock? Is it soil salinity? high soil boron? high pH? I've seen good avocados growing in highly alkaline, saline soils in northern Egypt, but don't know what kind of roots they were on. And certainly, as long as soil moisture is adequate, most avocadoes don't mind summer heat.

'Waldin' or other pure West Indian race types will handle high pH better than Lula seedlings, but Lula is otherwise a good stock.

A little of all the above Doc...
Winter temps are the biggest issues for un-established trees (and sometimes established ones), every once in several years we get a real cold front swing by, in 06 I had 4 days in a row with 19 degree temps sustained, there is high salinity throughout the valley here and soils that hit the 9pH in some areas. Calcareous soils are about the norm here.

Doesn't low humidity come in play here in AZ as well? I read they simply dry out too quickly here.

It can but the few trees that are in and around the valley are in the most part on flooded lots and have a great deal of other foliage thus creating their own small micro-climate. Under correct irrigation conditions you'll end up creating your own radiant humidity, most people would call it "steam" lol
When we deal with 115/120 temps and 5% humidity for months on end another major issue is sunburn, same thing with young apples until they develop bark.
Arizona is a little unique in some of the growing ,, the principal is the same, just provide the plant with what it needs

MrTexas -- I don't know about the guy south of San Antonio, but no, this was budwood from a backyard seedling (yard of the real lady, Mrs. Holland), given to me personally. I don't believe it has ever been in the commercial nursery trade.

Re. Arizona conditions -- granted a stressful situation. But I've seen similar (other than the lowest winter temps) in northern Egypt, and they seem to do well there. Certainly, daily temps above 110, very low humidity, no clouds, high pH saline soils, are all present there. OTOH they were using astonishing amounts of Nile water to make that happen.

I have been interested in hardy avocado varieties. In the July and August 2009 California Rare Fruit Growers magazine there was an article about an Avocado tree from the Aravaipa Canyon in Arizona. This was a mature tree that was able to take the heat and cold well from this area. This tree has been propagated. At this years Carpinteria avocado festival a representative from what I believe was Calavo had different sample avocado varieties including Aravaipa on display. I think he said that they were from the UC collection at Irvine.

Logees, web site claims their Day Avocado is a self fertile avocado. - Millet

The other very cold-hardy types that we grow tend to be type A, but that may just be coincidental. I don't recall looking at Mrs. Holland flowers to know for sure. Many avocados will set fruit if the weather is chilly when they are in flower, and in cold climates, that tends to be the case. My tree is probably at least 300 yards from the next nearest avocado tree, and it set a heavy crop this year.

Macolm Manners,

How large and old is that tree?

It is the Mrs Holland that you grafted correct?

What rootstock?

Thanks,

Charles, The tree is probably 3 or 4 years old (2.5 years in the ground). Yes, grafted by me. I'd guess it's 8-9 feet tall by about as wide. It is grafted to a seedling, likely either of 'Gainesville' (pure Mexican) or 'Brogdon' (Mex x West Indian hybrid) -- I don't remember which.

It bore a few fruit last year, and a heavy crop this year.

In avocado, rootstock has no effect at all on the hardiness of the scion, as is the case with citrus. However, if you use a too-cold-sensitive stock under the scion, it's possible for the stock to freeze out from underneath, and you lose the tree even though the scion technically was not damaged. Back in the late '70s, Dr. A.H. Krezdorn at U. of Florida used to graft his hardy stuff to West Indian stocks, for more vigor, then bury them deeper than the union at planting time to protect those stocks from freezing. This was in Gainesville, and they did quite well that way.

If you use a pure Mexican rootstock, it is likely to be hardy, but it will be less vigorous, and the seedlings tend to start out quite thin, so it takes longer to get them big enough to graft.

I have visited Bill Schneider of Devine Avocados many times. He says he discovered the 'Mrs. Holland' avocado growing in the backyard of Mrs. Opal Holland in Uvalde, Texas. He calls the variety 'Opal', and has trademarked it. Treesearch Farms is licensed to propagate it, and Opals are commonly sold at nurseries in the Houston area. I have never heard of an avocado hailing from the Dallas area.

I had not heard that story before, but our Mrs. Holland definitely lived in Dallas, which is where I got the budwood, freshly collected. So it must be an entirely different variety, despite the name. Or perhaps their husbands were related, and they shared the variety? Who knows?

What do you know about Opal? Do they look the same? This 'Mrs. Holland' is strongly pear shaped with a narrow neck. The size of a jumbo chicken egg. medium green, shiny when immature but turning dull (still green) when ripe. Very grassy if picked early, but if fully mature, it has an excellent, nutty flavor.

Any idea when he found his version? I suppose there is also the possibility that the same lady moved and took a tree with her. I got my budwood in probably the mid- to late 1980s.

By the way, my post of December 2010 was in error -- it said the fruit turns black. Not so -- it's green to full ripeness.