Fuerte avocado tree: male flower dominance as the cause of poor fruiting?

@californication thanks for the comparative information about San Jose and other cultivars. I would be curious to know what the temperatures are when you see B cultivars set fruit in N Cal. My hypothesis is that it is probably when things are warming up? April?

In the hopes that these observations will help someone troubleshoot Fuerte production… Today was the first day this year that Fuerte was in female stage at all. So its bloom from late November to now was exclusively male, the entire day… and actually, even today it was male until later in the afternoon. The nice thing about Fuerte though is that it keeps trying. It is often in bloom nearly half the year. I have a colleague at work who has a mature Fuerte tree. She lives closer to the coast. Her tree is always loaded. I wonder if in areas where it is not as cold at night, Fuerte sets better.

The traditional view is that the switch to female stage flowers is driven by daylight and time of day, but I do not see that where I am. It seems to be temperature. When it is cold, it “aint” switching. And then, typically in April, it begins to behave according to dogma (female stage in the afternoon). The high was 75 today and the low was 50 at night. That is typical of what I have read, it does not set well when it is colder than that. Fuerte might be famously cold hardy in its origin story but it does not seem to set fruit when it is cold.

I hope for a good crop but there are ants all over the tree, taking nectar from the flowers. This not only robs the flowers of the attraction to bees, they also have potential to harass the bees. I did set out bait when I realized the problem recently. I had noticed a similar issue with my cherries and ridding the ants did seem to help pollination/production/bee density. It is just anecdote but something to at least consider for those in marginal areas for Fuerte production.

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I think in general it’s been determined that temperature is in fact the most dominant cause of flower timing for avocados. The Western Australia pages I linked in an earlier post in this thread say this, for example:

Under cooler conditions, the flowering story becomes more complicated. Extensive investigations into the effect of temperature on flowering of avocados have been carried out (Ish-Am and Eisikowitch 1991, Sedgley and Annells 1981, Sedgley and Grant 1933, Sedgley and Alexander 1983). Cold temperatures alter the flowering cycle by delaying the normal opening and closing routine of the avocado flower, extending the overall period of flowering, delaying the release of pollen, slowing pollen tube growth and reducing the number of flowers open on a given day.

Research by Sedgley and Grant (1983) into other varieties, both type A and B, has shown similar effects to different temperature regimes, though with some differences between varieties.

The delaying effect to type B varieties is so pronounced at low temperatures that the functionally female stage was often not recorded. This has a dual effect:

  • If there are few functionally female flowers then the cropping potential of the type B varieties will be severely affected.
  • Delaying of flower opening has been recorded to result in the peak pollen release period occurring during the night (Sedgley and Annells 1981).

Therefore, as the temperature regime is affecting the flowering cycle of flowers of both type A and B varieties, then the choice of a suitable cross-polliniser is not a simple case of choosing a known complementary flowering type. You will need to investigate the effect of the local temperature conditions on both varieties to see if they are indeed complementary. A single year of observations in 2009 in the South-West of Western Australia demonstrated similar results to those reported in the literature — see ‘Cross-pollinisers for Hass avocado’ for more details.

There is a very old Sir Prize avocado at Emma Prusch Park in San Jose that does quite well. It does alternate bear but I have yet to see it go fruitless in the last 4 years I have been observing. Maybe it’s just a matter of them getting some size ? And as you said, Fuerte keeps flowering for so long. Sometimes into April. And we do see day time highs of 72 and night time lows of 55 around that time.

@swincher I am sure there are other factors at play here. Bacon and Zutano are B types that bear consistently. I think we need a new metric. Maybe something like “temperature thresholds for female flowers”.

In fact, Bacon outproduces Hass consistently here. And does not show any alternate bearing.

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I have Bacon and Hass for cross pollination, so far Bacon has nothing, Hass is a huge tree bearing fruit already.

Bacon takes some time. My neighbor’s tree didnt produce well till it was 10 ft tall and wide.

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I definitely don’t think it’s to do with Santa Cruz Vs San Jose because they acknowledge Bacon and Zutano as exceptions to their hypothesis. They also called out these exceptions in their CRFG talk as varieties that produce well in Santa Cruz. Also, there are exceptions in a specific year as well - Sharwil never fruited for them but when I visited them in 2020, it was full of fruits. Ellen said this is the first time in 20 years Sharwil did that.

Without distracting this thread too much, do you know the ripening times for Bacon, Reed, Lamb, Jan Boyce, Fuerte and Phoenix varieties in San Jose? What are your favorites for locally grown avocados?

In a typical San Jose summer,
Bacon - 10 months , consistent production
Reed - 18 months , consistent production
Lamb - 16 months , slightly alternate bearing
Fuerte - 7 months, (bearing habits depend on who you ask :smiley: )

I personally grow Lamb and Reed

Lamb is a super hanger. The fruit seems to hang on for more than a year once ready. It sets its fruits deep inside the canopy and the critters leave them alone.

Reed is very consistent. But it takes 18 months to ripen on the tree and the critters find them. The tree needs to be propped up to support those delicious cannon balls.

I want to try growing Fuerte. I tried them at my friend’s place and it seems head and shoulders above any other variety I have tried.

And Bacon and Zutano and Jim Bacon are fruiting well despite them being B types. So there should be something specific to them that is bucking the overall B-Type trend. Little Cado is also a B type and this guy seems to be getting a lot of fruit. He is located further up north in Richmond

My friend’s Fuerte tree does alternate bear. But it never has a year without any fruit. She does not even have an A type to complement it.

Emma Prusch park’s Sir Prize was loaded last winter. I go there every winter and there is always some fruit.

I really think that we need to try these types and get a better understanding in the much warmer climate of San Jose.


Thanks, great info. I’m growing these varieties except for Fuerte in San Jose as grafts on the same tree. They started fruiting in 2022 and hopefully ripening up this year. I might plant one more or if the random seedling in my yard grows well, I should try grafting Fuerte on it

Do the Northern California avocados still taste as good as those in Southern California? Or at least close enough that it is worth the effort?

Hard for me to answer. The ones I tried from local trees are better than store-bought but that doesn’t say much. Other than longer period of cold, I am not sure what’s the difference between Nor Cal Vs So Cal for avocados. They do take longer to ripen here. Not sure how that influences the flavor

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I think NorCal weather is quite diverse. San Jose is shielded from the coastal fog and gets much warmer. I have seen many mature 50 footers here. Also, we don’t have to deal with Santa Ana winds :D.

There’s a guy called Gary Gragg on Yoututbe who goes around documenting these trees. There were commercial plantations further up north in Butte County. That’s where the Duke avocado was discovered.

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Hey, I think our area is well known for avocado for a reason. Not too far from me, I saw tons of avocado trees.

Which part ? NorCal ?

I’m in SoCal hence my name.

Of course. Socal is much better for avocados. :slight_smile: . I was not claiming Norcal is better. The 5 degrees cooler winters do make a difference. But not THAT much for home growers like us.

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Agree. A challenging climate fit does not necessarily mean the flavor is inferior. I have been growing moorpark apricots for half a decade and I get 12 to 40 a year but they are amazing.

Let us know how you think the avocado flavor compares?

Also, post photos of the trees. I have sometimes noticed avocado trees when I am walking around in the neighborhoods in the bay area and they tend not to look very healthy but that doesn’t prove they can’t be healthy.


My goal for my (primarily avocado focused) greenhouse is to mimic the low temperatures of somewhere like San Jose, though the highs are a bit warmer in summer and a bit cooler in winter. Here’s Jan 1, 2022 to today, so a bit more than a year:

Next winter I’m dropping the heater even more and will let it get to the mid-30s. Eventually, once the trees are a good size, I’m hoping to stop heating it at all, other than for rare extreme freezes. But I’ll see how low it can go without making the trees visibly suffer, and may turn the heat back up if needed.

@JamesN Here are the Spring averages for Atlixco, Mexico. The city where Fuerte comes from

I guess this kinda confirms that they need daytime highs in the low 70s and lows in the mid 40s to set fruit. We start seeing these temps late March to early April here in San Jose. 2023 is a different story :smiley:

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Great idea to check that! That makes sense of this! Yes, Fuerte fruits best when it “feels like home.”

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This San Jose vs Escondido chart makes a lot of sense out of things for me, more for stone fruit than avocado.

The only thing it does not capture is the swings of temperature. Most winters in San Jose there is a 15-20 degree or less swing in temperature night vs day, and in Escondido it is more like 30, or, exasperatingly, even 40. (this year was uncharacteristically more like 20 though).

Thanks for sharing this. It sheds light on why I have generally had decent success growing things in Escondido that have been proven winners in San Jose.