The Tropical Fruit Forum

If you ever burn wood you can cover it to encourage charcoal formation then powder the charcoal and add that to your soil (biochar) to form "terra preta". It absorbs and holds water and dissolved nutrients. You can add up to about 10% by volume. Its first action is to absorb moisture and nutrients so can produce a transient depletion of nitrogen. You can avoid this by pre-dosing the charcoal with fertilizer or compost tea.

This image is interesting, and theoretically it helps. But in practice I don't understand how the same size cut could have either the result in the second or the third drawings - seems to me it should be one or the other. That is to say, the cuts in the second two drawings appear to be almost the same width, but one has the cambium only on the edges, the other has it in the middle. I don't see how the same width cut could have two such different results.
The cut that Mr. Zill does for the second graft in the video looks to me like it should turn out like the second drawing, requiring lining up at least one side. But he centers the scion a la the third drawing. That's what has me confused.

I'm no expert on grafting either but I'm doing my best to learn. The two drawings to the right in my previous post illustrate cuts at slightly different depths with the second one cutting along the cambium. In both cases however, the rootstock bark layer is thicker than the scion bark layer - because the scion is a smaller limb and additionally the rootstock layers are cut at an angle which makes them appear even thicker in the plane of the cut.

Zill describes the cut between 5:15 and 6:15. His first cut appears to go through the bark and into a lighter color layer but he says it isn't deep enough and cuts more off, then points down the middle of the removed piece and the cut on the rootstock to a slightly darker area that he calls the cambium and describes as "juicy". I suspect that the confusion may come from assuming that the "bark" is just the dark layer on the outside whereas this isn't really the case. Cambium layer cells produce layers of phloem cells on the outside of the cambium that are alive and growing. They are the cells that form the transport system for materials up and down the stems and trunk and are usually whitish. This is the lighter brown ring in my diagrams. This page illustrates the 4 possible layers of bark outside of the cambium - phellem, cork cambium, phelloderm and phloem. The phellem is the only dark layer. This video has a good general explanation of plant growth, including the secondary growth accomplished by the cambium layer. This page has a photograph of the section of a trunk identifying the cambium and inner bark (phloem) layer. If you magnify the image you can see the outer bark is a darker color.

It's a bit of geometry. With a veneer graft you are slicing a bigger rootstock along the perimeter of the circular layers of bark, phloem, cambium etc. so the cut is at an angle rather than straight through the layers which makes them appear thicker. A thinner scion is cut more along the centerline so the layers are thinner and all the layers won't line up exactly with the rootstock. The cambium layers are the important ones to line up. The bark and phloem layers on the outside of the cambium won't be as thick on the scion as they are on the rootstock so it is likely that some veneer grafts won't line up exactly.

The idea is based on the air well and isn't universally accepted.
It is a similar process to dew formation and depends to some extent on local conditions. Try a small pile and see if they gather moisture. Apart from that, stone prevents water evaporation from the soil surface by reducing exposed soil area and reducing surface air movement. Gravel works as a mulch and is easy to keep clear of debris with a rake or blower.

Anyone know how to contact the growers in the Salton Sea?

A couple of articles with leads found with a Google search.
http://www.theproducenews.com/category-list/9-story-cat/1498-1367
http://www.sunset.com/travel/california/mango-madness
http://newamericamedia.org/2017/08/coachella-rising-aging-farmworkers-unions-organic-mangos-the-salton-sea.php

As Simon said, the major growing area is the Coachella Valley around places like Mecca.

Wong farms supplying Santa Monica farmers market https://www.wongfarms.org
Tilden Farms - Fruits & Veggies - 17055 Van Buren Blvd, Riverside, CA 92504 (951) 780-2200 https://www.yelp.com/biz/tilden-farms-riverside

Calcium Hydroxide is used on gardens but is about 50% stronger than calcium carbonate. It is somewhat caustic so it is advisable to use gloves, eye protection and a breathing mask when you use it. It is also more soluble in water and therefore quicker acting.
The pH of a calcium hydroxide solution is about 12 compared to a carbonate solution pH of about 9.

There is an FDA salmonella alert for Mexican papayas right now.

I've grown a few Maradol from seeds and just eaten my first fruit. It's the first time I've been really impressed with a papaya. Much better than its store-bought parent. Not sure if straight from the tree had anything to do with it but it was sweet and delicious. I put some of the cut pieces in the refrigerator to keep and a day later the flavor is really disappointing.




Thanks to several TFF members for helping me get them through a bug attack earlier in the year.

Vise grips?

I use gravel mulch under mango trees and around cactus with no problems. The few weeds that come up only take an occasional few minutes to remove by hand. My climate in Baja California has only a few rainy days (if any) per year so the surface soil stays very dry and inhospitable to weeds.
The mangoes have been great this year so the trees must be OK with it.
One minor problem is that the gravel tends to migrate if it isn't contained or constantly raked back into position.

Just following up on the pitaya post now the fruit is ripe. Sorry it's a bit fuzzy - and big. It took me two tries to figure out the new posting feature.

Still not very tasty and not much to eat. The fuzzy pea-sized bits around the fruit originally covered the fruit and contain nothing.
The pitaya dulces are just starting to form. This is a baby plant in my garden with a single flower bud.

Manzana www.researchgate.net/profile/Galvez-lopez_Didiana/publication/259623358_Morphological_Characterization_of_Native_Mangos_from_Chiapas_Mexico/links/0c96052cf0d87207d8000000.pdf&hl=en&sa=X&scisig=AAGBfm2GQXp93VEBORjVauZjo3tzcoxPFQ&nossl=1&oi=scholarr&ved=0ahUKEwim5vPU9OrUAhUCMyYKHb96BLIQgAMIHygAMAA

I think I'm having the same problem here with a tree that was overwatered.
It has been a little hotter than normal with no rain here in Baja. My ataulfos taste spectacular this year and that seems to be the general consensus among folks here who grow mangoes. Other varieties seem about normal (mamay and manzana - sorry, I haven't managed to trace their provenance).
One of the ataulfos has been overwatered for the entire year - to the point where there was always a small amount of standing water around the trunk. It is a mature tree - about 30 feet high with a 14" diameter trunk. The first notable effect was a massive leaf flush after flowering which didn't occur in the other trees (including other ataulfos). The second effect is that the fruit on this tree is only just ripening - about a month later than the other ataulfos. The fruit doesn't taste quite as good as the other ataulfo. Washed out would be appropriate. However, it's early days yet for this particular tree and I'll update when/if the fruit improves over the season.