Join me as I join the California Rare Fruit Growers, North County San Diego chapter, to talk about “Avocados: Varieties and Heat” on Friday, September 11 at 7 PM via Zoom, meaning from the comfort of your own computer or phone.
The presentation will take about 45 minutes with some time for questions and discussion afterward.
Here is a recording of the presentation and the questions and answers that followed (sorry that the first few minutes were not recorded):
Good afternoon Greg. Unfortunately I won’t be able to attend your zoom presentation tonight but I would like to know if you are going to posted on youtube. That would be great if people can still watch it if they can’t make it at 7. I know I would enjoy it like the others that I have the pleasure to watch. Have a great weekend and I hope your trees are okay after this past heat wave
Hi Mary Ann,
Sorry you can’t join us. The presentation will be recorded, and I’ll see about posting it on YouTube. Thanks for the request.
Thank you so much for replying to my request. Have a great weekend and the best of luck in your presentation
Hi Greg, thank you for your presentation tonight, it was great. I have a question. In an abandoned field near my house there are several relatively healthy avocado trees (no water for 15 to 20 years) and they have good fruit this summer and small fruit on them now. Some are Hass but one is not and others I am unsure of. I air layered several branches and was thinking of planting them directly with no grafted root stock. What do you think, am I wasting my time?
Hi Michael,
Thank you very much. I think it’s a great idea to play with cloning these trees. The only thought I have is that I’d be just as interested in the rootstock, for it is also (maybe primarily) the rootstock that is allowing these trees to survive on their own in these conditions. But propagating the scions is a worthy endeavor too.
As far as growing them on their own roots, I’d guess some will do better than others, and they won’t grow exactly like their mothers who have different rootstocks. But at least you’ll have the genetic material in your possession in case someone decides to remove the old trees.
Where approximately are these trees located?
They are in Fallbrook, just 2 lots down from my house, a big property (maybe 100 acres), beautiful property. I could post some pictures if you like. There are quite a few other surviving trees on the property, fig, peach, pecan…
Well I went out in the field to check the avocados and found the heat had caused a fair amount of stress. One tree that had quite a few avocados it turns out were seedless. I ate some of them, they were small long and skinny shaped. The peels were soft and edible, I could have essentially eaten them right off the tree. And quite tasty but some were under ripe and too firm. My air layering on that tree also suffered from the heat and just didn’t produce any roots. That tree does not appear to be a grafted tree. But I like it because of its drought tolerance.
Interesting updates. Maybe graft a branch from it onto another tree to see if it shows less leaf burn in the fall than the other variety so you can more directly compare drought/salt tolerance.
I would love to view this, too! I am only now reading the e-mail so I’m way past catching the live Zoom.
Hi Greg, I sent you the photos of my reed with two beach umbrellas 12′ high and two bed sheets suspended on the south and west facing sides. As you suggested I wet the leaves on the reed 5 or six times during the day. Maybe 5 or 6 burnt leaves and we hit 111 degrees in Mission Viejo. I could only hose my fuerte as I didn’t have more umbrella or posts to protect it. But it two was hosed and surprise only the very top new growth leaves were fried. Again only a few. Also not one single fruit drop. I also watered well for two days before on both trees. Your advise on prewatering and spraying during the heat of the day really paid off.
Awesome, Ron. Thanks for the feedback. Glad your trees have made it through that weather relatively unscathed — because of your attention.
Hi Greg. Thanks for the awesome presentation on heat and avocados. We met during the last fruit festival when they took us to pass by avocados and only talk about coffee plants. The suggestions you gave me about pre watering the trees before the heat hit saved my trees this time. I watered my massive fuerte and zutano soaking and slow dripping all around for at least 3 days and then sprayed the tops with water every hour during both scorcher days. We reached 115 here in Glendale/ Burbank. I realized that the water being inside the tree was the most crucial. There are a lot of branches that even grow under my hot tub structure so completely shaded and even they lost a few tips so its not just the sun, the new growth does always go first. I have a hass, lamb hass, bacon, and mexicola and they got a bit of browning but will be ok. They are all shaded with other” friend “trees . I will be trying the sprinkler head on a pic riser in the future or building a misting structure. Thanks for all the advise and hope the hell temps are over this year.
Hi Bita,
I remember so well. You had a beautiful wooden spoon with which to eat your lunch, and you mentioned that you insert a tub into your sink so you can easily dump the gray water out in the yard.
So glad to hear that your big Fuerte is doing well. And thanks for noting that even branch tips in total shade still got burned, showing that it’s not exactly sunlight but heat that does the damage. During the July 2018 heat wave, I made the mistake of wrapping a small avocado tree in shade cloth on all sides and over the top, and later I lifted up a side to check on it to find that it was hotter under there than outside, and the tree was not happy about it. Once I raised the sides so air could flow, then I got the cooling effect that the tree needed.
I can also attest that avocados in the shade will burn in the heat. I recently bought a few avocado trees from Eli at subtropica, I planted the in a 15 gal pot because I wasn’t ready to put them in the ground. For the heat wave I moved them under the shade of my back porch. I didn’t think I needed to paint them because they were in the shade from 11am on. They are all burnt now. I think the Mexicola took it the best. The trunks are browned just like sunburning almost al the way to the graft point even though they were shaded, the majority of the leaves are crispy. I’m going to keep caring for them and see if they can come back strong.
I also wanted to comment on avocados growing in lawns that you mentioned. I have my two large trees with st augustine grass surrounding them and they are happy if the grass is happy. I get that they are competing for water but I can gauge the water needs in areas by looking at the grass, I throw a lot of mulch and organic material around it too but the grass goes over. I also have 2 compost bins on one side and I water in them sometimes so I think the fuerte likes it. The fuerte is one of the reason I bought my house. It was about 40 x 40 before the 2018 heatwave hurt it but she is bouncing back and full of fruit with none dropping last week.
Hi Bita,
Thanks for adding this, especially the details about how the status of the grass helps you see the status of the trees.
Thank you for your incredibly informative posts. I credit you with saving my recently planted Fuerte and Hass trees (Hass is a baby) during the Labor Day weekend extreme heat wave. They both were planted 2 months ago and I whitewashed them both and built shade structures after reading some of your past articles. In the past I lost 2 trees to sun and heat damage and then 2 more in the Woolsey fire of November 2018. I did some reading before these newest trees were planted because I am determined to grow some avocados! I live in the Santa Monica Mountains above Malibu. Both trees had tons of new growth last weekend when the heatwave hit. It was 109 at our place and we lost about 30-40% of the new growth but I think both trees are going to make it. I watered them heavily for the day before and both days of the scorching heat. As others have noted, even some completely shaded leaves were damaged. I have a question moving forward. The fuerte is about 14 feet tall and grew up in complete shade at the nursery. I have it whitewashed and shaded above and to the south and west. It’s getting established and I can tell because of a lot of new growth. It gets windy up here in the next few months and I am worried about the structure being left up with the equivalent of sails on them. Can I just leave the 12 o’clock straight above shade on the structure and remove the other 2 until another heat wave? Any advice appreciated. Again keep up the great work! Phillip
Hi Phillip,
This is great news. Sounds like your trees are going to be fine. This is the time of year when I start to remove shade incrementally. I think you can safely remove the side shades. You can probably even remove the top shade, but you might want to leave it on until the end of September or whenever we get our first spell of Santa Anas (so it doesn’t take off in the wind). You are growing in some tough conditions; I wish you the best.
Lots of good information on your video….even more questions.Regarding watering of trees – if the stomates close up once temperatures reach the 90’s, to get water to the leaves isn’t it best to water when temps are below this ? The benefit of watering when temps are 90+ is the increased humidity. Is this correct to say? What is the watering schedule before,during and after a heat wave.? I am planting 400 new trees next year in Temecula /Deluz area and will need to start planning…
Hi Jim,
Yes, that’s exactly the process as explained by farm advisors and researchers. You water before the heat arrives because once the heat arrives the tree has shut down (stomates closed) and is unable to take up water. I’ve watered some trees the morning before a hot afternoon, but that seems later than ideal. When I’ve watered the day or even two before the hot day, trees have seemed to withstand the heat better, maybe because they had more time at lower temperatures to draw the water into their system. That’s my guess.
Watering during heat will increase humidity, as you say. And then it also has a cooling effect on the top of the soil and therefore the roots there (avocado roots fry in high heat). What I’ve also noticed is that the water applied during the heat remains available to the roots as soon as the temperature lowers again such that if I pulse irrigation (with micro-sprinklers) during high heat I often don’t need to irrigate again immediately after the heat subsides.
I don’t know that there’s a watering schedule that everyone can follow before, during, and after heat because a lot depends on the age of the trees and how they’ve been watered just prior to the heat event, among other factors. But what I’ve heard often recommended, and what has worked for me, is to water a day or two before the heat enough to bring the root zone to field capacity (in other words, totally replace any water the tree has recently used) and then add 50 percent. So, for example, if you need to water for two hours to replace soil moisture, then water an additional hour on top of that for a total of three hours. That “pre” irrigation is the most important irrigation practice in getting trees through heat from what I’ve seen.
Hi Greg,
Thanks for your presentation – it was informative and well constructed. I practiced some of the tips you mentioned – misting the leaves and watering in advance during this September heatwave – and had positive results. I have a 3-foot Sir Prize in full sun that suffered new-growth burn in August; it had no damage during the most recent heatwave with the help of these techniques.
Looking forward to more of your videos and posts,
Vin
Thanks, Vin. Great to hear this feedback.