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farbatlas

avocado leaves get brown spots

Farbatlas
9 years ago

Hi,

this is the third avocado-plant that I managed to grow and they have never gotten this big (about 70cm) so I thought this couldn't go wrong.
About 4 days ago it proved otherwise;
Some of the leaves started getting brown spots, very tiny at first but they kept getting bigger.
Not all the leaves have it (yet) but I really want to avoid having to throw the plant away (again)
I've searched the web relentlessly but I couldn't find a clear answer.
How I treat the plant:
-water it once every 2 days (it has quite a small pot so it dries out pretty quickly)
-fertilise every 1 or 2 months
-I keep it indoors obviously since in Belgium temperatures are Always too low
-I keep it out of direct/hot sunlight

That's about it, I haven't done anything differently that would explain the spots, the roots are OK. The leaves don't turn brown from the tip on but just start getting spots randomly.

Any suggestions on how to fix the spots?
Thanks!

Comments (16)

  • greenman28 NorCal 7b/8a
    9 years ago

    Can't tell.
    It's probably in too small a pot and root-bound. Can you post more pics?

    Josh

  • Pak Gelatin
    8 years ago
    last modified: 8 years ago

    I have the same problem with mine . Please, if you find the solution let me know. My e-mail is pak.gelatin.oru@gmail.com

  • dale92539 Riverside Co SoCal
    8 years ago
    last modified: 8 years ago

    UC Davis Page on Avocado Diagnostics

    http://ucce.ucdavis.edu/files/datastore/530-27.pdf

  • Rachel Deanna
    7 years ago


    I'm also having a hard time for two issues with mine. It's like every 3 years I get the black stem of death. Leaves turn brown, and then the stem goes black from top and slowly goes down.
    I thought in December I caught it, by reading I assumed it was this fancy name for a fungus. I checked the roots and sure enough it was root rot. Cut the black roots, they were brittle anyway. Then gave new soil, a solution called hydrozyme and biothrive and thrive alive b-1 green. Not all combined. Mostly hydrozyme to help healthy roots thrive.
    I saved it until Feb I saw new growth. I had pretty much left alone with a bag on it. Excited, I watered a few weekends ago, bc I believed it needed it, (new growth). Right away black stem started doing the same thing. I have cut the stem, checked roots, did what I could, but atlas it's gone.
    I have yet to find anyone with black stem of death. It's been frustrating.
    I have 5 other babes, 3 that are 1 and 1 that is 2.5 and a baby about 2 months.
    I've noticed for my twins the leaves have white faint spots and on another leaf, darkish splats of dark brown.
    My pH is within avocado range...I'm not over watering but I'm not going more than 2 weeks without water. Just hard to find my issues online. Hoping I found the right group.

    I have gone to talk to local nurseries, but no one knows much about avocado plants.

  • tapla (mid-Michigan, USDA z5b-6a)
    7 years ago

    Show us a picture of the soil you're using? It sounds like excess water retention due to a combination of a water-retentive medium and a heavy hand on the watering can. It's likely all that's needed to get you in the groove is a soil that allows you to water correctly and learning to appropriately monitor your watering. Part of the reason I said what I said is how much the odds favor over-watering, the other half is what you said sort of supports over-watering as the issue. Depending on how much effort you want to put toward making sure you're providing a home for roots in which they can be happy - there ARE soils that relegate over-watering to pretty much 'non-issue' status.


    Al

  • Filipp V
    3 years ago
    last modified: 3 years ago

    Hi, Tapla! @tapla (mid-Michigan, USDA z5b-6a)


    Seems you know your stuff very well. :) Could you please give me any advice as well. My leaves are getting brown spots as well - it seems to be as you described Oedema. Whats the right soil for avocado tree? Measured pH of my soil its 7. Attaching some pictures. Any information would be much help. Thanks a lot!


    Filipp.






  • tapla (mid-Michigan, USDA z5b-6a)
    3 years ago

    Hi Filipp. I don't think pH is the issue, but how did you determine the soil's pH?

    At a glance, the growing medium looks very water-retentive, and the symptoms (necrotic leaf tips/margins) point toward over-watering or a high level of dissolved solids (salts) in the medium, perhaps both if you've been allowing the plant ti sit in water that collects in the collection saucer.

    Whats the right soil for avocado tree? I think the delineation between good/acceptable and poor soils pivots on whether or not you can properly water plants growing in it without having to worry the soil or parts of it will remain saturated for a prolonged period, thereby affecting root function, or worse, root health.

    Early spring is the best time to repot avocado. That's something I'd put on my schedule, to be completed at your earliest convenience. The 2 media I make myself and use look like this:



    You can see they are very chunky, which discourages water that would be retained in media made of fine particles and saps potential from the plants growing in it. A healthy root system is a prerequisite to a healthy plant, so soil choice is a key element of growing well.

    When you're ready to repot, we can talk more. Until then, you can try these practices:

    Water over the sink, completely saturating the medium and flushing it well to leach any accumulation of salts from the soil. After you do that, hold the pot over the sink and move it up and down. You'll immediately see that on the reversal from downward to upward, Newton's First Law of Motion takes over and the water in the soil continues to move downward and out of the drain hole. Repeat until no water exits the drain hole - the sharper the reversal from down to up, the more water will be forced from the soil. This simple trick can remove all excess water from the soil and be a very significant benefit to your plants' vitality. Use it for all your plants in pots light enough to be manageable.

    If you haven't, you will need to start fertilizing soon as nutrients provided by the seed cotyledons will soon be depleted. I suggest you use this:


    It contains everything a plant needs to prosper, and you'll need nothing else in the way of nutritional supplements. In case you would like some reference material to look over, the following links, if put into practice, will allow you avoid all of the most common stumbling blocks you would have to deal with otherwise.

    An Overview of Good Growing Practices

    Caring for Trees in Containers

    Container Soils - Water Movement and Retention


    Al

  • Filipp V
    3 years ago

    Hi,


    Thanks a lot for a detailed information. It is very helpful.


    I have a soil ph meter.


    Collection saucer collected very little water comparaing to what I poured on top. I think I found the biggest problem the pot had only one tiny hole at the bottom so water flushed very slowly. I dont know how I didnt notice it when I was planting it to that pot. I made more and bigger holes so now it passes thru much faster.


    In this thread using "UC Davis Page on Avocado Diagnostics" pdf I thought that my avocado is lacking of zinc. So yesterday I watered it. I have this zinc plant oil. Couple of drops in to water and water it with it. Water went thru very very quickly comparing to what it was before I had only one tiny hole. I hope zinc wont do any bad.


    Yes I will repot it in couple of days. Should I take a larger pot? And correct me if I am wrong, but do I understand correctly that media you are making you put it at the bottom of the pot and on top ordinary compost like soil as mine?





    Yes fertilizing was in my plans in this week, thanks on advice to which fertilizer to use.


    Thank you,

    Filipp

  • tapla (mid-Michigan, USDA z5b-6a)
    3 years ago
    last modified: 3 years ago

    I have a soil ph meter. I wanted to make sure you knew testing pH involves more than simply inserting an inexpensive (I'm making an assumption here) pH meter in the soil and reading what it says. Collection saucer collected very little water comparaing to what I poured on top. If you're watering in small sips, such that irrigation water only occasionally makes it to the collection saucer, or, only a small amount of water makes it there each time you water, the practice invites a build-up of salts in the soil from tapwater and fertilizer solutions. These need to be flushed from the soil regularly. Best would be every time you water, but at least every 3rd or 4th time you water. I think I found the biggest problem the pot had only one tiny hole at the bottom so water flushed very slowly. I dont know how I didnt notice it when I was planting it to that pot. I made more and bigger holes so now it passes thru much faster. No harm done with the extra holes, but whether you have 1 or 50 holes has no bearing on drainage, which isn't a measure of how fast the soil drains; rather, it's a measure of how thoroughly it drains. Plants don't care if it takes 60 seconds or 6 minutes for the pot to stop draining after a thorough watering. The key element is how much water, and particularly how much excess water is retained in the medium when the pot has stopped draining. You can also use a wick to your plant's advantage.

    Experiment: When your pot has stopped draining after a thorough watering, push a toothpick through a drain hole just far enough it will remain in place. Notice how much more water exits the pot by dripping off the end of the toothpick. Rayon mop strands as in the images work really well as wicks. Or, use the method I described in my post upthread.









    In this thread using "UC Davis Page on Avocado Diagnostics" pdf I thought that my avocado is lacking of zinc. So yesterday I watered it. I have this zinc plant oil. Couple of drops in to water and water it with it. Water went thru very very quickly comparing to what it was before I had only one tiny hole. I hope zinc wont do any bad. Hard to say what will come of it. It's very highly unlikely your plant is suffering a zinc deficiency. Generally speaking, dosing your plant with this or that because you think "it might like it" or "somebody said product X is great for plants" is far more likely to be limiting than beneficial. Many growers are convinced that "bloom booster" fertilizers actually do what they avouch when used on containerized plants. The truth of the matter is, they provide so much phosphorous it causes limitations on several fronts. Plants need only minute amounts of zinc (why it's a micronutrient instead of a macronutrient); and, an excess of any single nutrient has the same potential to limit as a deficiency. Yes I will repot it in couple of days. Should I take a larger pot? How large the pot can/should be is highly dependent on soil choice. See "Choosing Container Size below" And correct me if I am wrong, but do I understand correctly that media you are making you put it at the bottom of the pot and on top ordinary compost like soil as mine? Drainage layers are counterproductive because they cause water to perch (take up space) in the medium immediately above the drainage layer. Perched water is water that defies gravity and will not drain from the pot without workarounds or the grower changing to a medium that cannot/does not support it. Below, the shaded parts marked PWT represent a perched water table. Compare the middle pot with a drainage layer to the left image to see why "drainage layers" don't work.



    Also, the media I provided images of upthread is what I grow in. and pots are filled from bottom to about 1/2" from the top with one or the other. I've moved away from building the 30 or so mixed plantings for the gardens and decks, and no longer grow veggies in pots, both because my focus is primarily on bonsai, I now use almost exclusively what others here at GW/Houzz have named 'the gritty mix.


    Image of the root system of a plant in the gritty mix ^^^ - in the middle of a repotting session.

    Choosing an Appropriate Size Container

    How large a container ‘can’ or ‘should’ be, depends on the relationship between the mass of the plant material you are working with and your choice of soil. We often concern ourselves with "over-potting" (using a container that is too large), but "over-potting" is a term that arises from a lack of a basic understanding about the relationship we will look at, which logically determines appropriate container size.

    It's often parroted that you should only move up one container size when "potting-up". The reasoning is, that when potting up to a container more than one size larger, the soil will remain wet too long and cause root rot issues, but it is the size/mass of the plant material you are working with, and the physical properties of the soil you choose that determines both the upper & lower limits of appropriate container size - not a formulaic upward progression of container sizes. In many cases, after root pruning a plant, it may even be appropriate to step down a container size or two, but as you will see, that also depends on the physical properties of the soil you choose. It's not uncommon for me, after a repot/root-pruning to pot in containers as small as 1/5 the size as that which the plant had been growing in prior to the work. Plants grown in ‘slow’ (slow-draining/water-retentive) soils need to be grown in containers with smaller soil volumes so that the plant can use water quickly, allowing air to return to the soil before root issues beyond impaired root function/metabolism become a limiting factor. We know that the anaerobic (airless) conditions that accompany soggy soils quickly kill fine roots and impair root function/metabolism. We also know smaller soil volumes and the root constriction that accompany them cause plants to both extend branches and gain o/a mass much more slowly - a bane if rapid growth is the goal - a boon if growth restriction and a compact plant are what you have your sights set on.

    Conversely, rampant growth can be had by growing in very large containers and in very fast soils where frequent watering and fertilizing is required - so it's not that plants rebel at being potted into very large containers per se, but rather, they rebel at being potted into very large containers with a soil that is too slow and water-retentive. This is a key point.

    We know that there is an inverse relationship between soil particle size and the height of the perched water table (PWT) in containers. As particle size increases, the height of the PWT decreases, until at about a particle size of just under 1/8 inch, soils will no longer hold perched water. If there is no perched water, the soil is ALWAYS well aerated, even when the soil is at container capacity (fully saturated).

    So, if you aim for a soil (like the gritty mix) composed primarily of particles larger than 1/16", there is no upper limit to container size, other than what you can practically manage. The lower size limit will be determined by the soil volume's ability to allow room for roots to ’run’ and to furnish water enough to sustain the plant between irrigations. Bearing heavily on this ability is the ratio of fine roots to coarse roots. It takes a minimum amount of fine rootage to support the canopy under high water demand. If the container is full of large roots, there may not be room for a sufficient volume of the fine roots that do all the water/nutrient delivery work and the coarse roots, too. You can grow a very large plant in a very small container if the roots have been well managed and the lion's share of the rootage is fine. You can also grow very small plants, even seedlings, in very large containers if the soil is fast (free-draining and well-aerated) enough that the soil holds no, or very little perched water.

    I have just offered clear illustration why the oft repeated advice to ‘resist potting up more than one pot size at a time’, only applies when using heavy, water-retentive soils. Those using well-aerated soils are not bound by the same restrictions. As the ht and volume of the perched water table are reduced, the potential for negative effects associated with over-potting are diminished in a direct relationship with the reduction - up to the point at which the soil holds no (or an insignificant amount) of perched water and over-potting pretty much becomes a non-issue.

    Al

  • Filipp V
    3 years ago

    Hi, Al!


    I have repotted my avocado just couple hours ago to an airier media. See photos attached. After that watered with 1,5L of water mixed with fertilizer. I hope it will help and be easier for me to use "tell" method for watering it. Thanks a lot for the information.




    Filipp.

  • Filipp V
    3 years ago
    last modified: 3 years ago

    Hi,

    Oeehhh seems it only getting worse. Used the tell method to measure the water level in pot. At the moment 25% of the pot is wet. Last time I water it when I was repotting it so it was 3 days ago.

    @tapla (mid-Michigan, USDA z5b-6a) help needed...







  • tapla (mid-Michigan, USDA z5b-6a)
    3 years ago

    If you read the links I provided upthread, and compare the suggestions to your practices, you should get an idea of the issues that need addressing. Because seedlings are composed of nearly 100% dynamic mass, they have a very strong "will to live", and will bounce back quickly after you've eliminated the offending cultural conditions. Still, tree time is tree time. Things don't happen overnight for trees; so, you'll need to put yourself on tree time, match carefully over what cultural conditions are, and be patient. I'm not surprised that leaves continue to present manifestation of the stress the tree has recently suffered.

    It would have been better if you'd waited until you saw evidence of new growth before you fertilized, but the world won't end because you did. If you learn what your tree wants, and all that info is included in what's upthread, then make sure that's what the tree gets, you should see improvement inside of a month's time.

    Al

  • greenman28 NorCal 7b/8a
    3 years ago

    If you just repotted, you need to keep the potting mix uniformly moist. Long ago I thought that avocados resented root disturbance because the leaves would brown and shrivel after repotting. Turns out they just need to be kept moist for a week or two while they re-establish roots in the new media.


    Josh

  • Vince O.
    2 years ago

    Avocado trees definitely need more sunlight, also watering every other day is far too much. try saturating the pot with water once every 5 days, allowing it to completely dry out in-between waterings. Fertilizer only needs to be added if you want it to grow faster, and every other month is too often. Instead try introducing other nutrients like boron, manganese, iron, and calcium once every 5-6 months, these will help boost its immune response system as well as encourage crop production. - ISA Certified Arborist (WE-12284A)

  • tapla (mid-Michigan, USDA z5b-6a)
    2 years ago
    last modified: 2 years ago

    How often trees in pots should be watered depends in large part on the physical characteristics of the grow medium, size of the plant's top mass, and weather, not the calendar. Allowing avocado to dry down completely ensures the death of fine rootage which does the lion's share of the tree's heavy lifting. Their replacement is required, which in turn requires an unnecessary expenditure of energy, before normal top growth will resume. When this becomes a cyclic event due to over or under-watering, it can rob the plant of an enormous amount of its potential in terms of growth, vitality, and appearance, so both extremes should be avoided except when growing plants/ trees well-adapted to arid conditions.

    No one can provide meaningful information re appropriate fertilizing intervals w/o a good amount of knowledge about the grower's watering habits and the physical characteristics of the grow medium in use. I grow in a fast draining, highly aerated medium and fertilize weekly in summer (when temps allow) at greater than a production level solution strength and have exceptionally healthy trees. In winter with plants under lights, I fertilize every time I water at a reduced rate and choose to do so because of the exemplary results the practice yields. Most growers provide nowhere near enough fertilizer because of inappropriately long intervals between applications or a solution strength too weak.

    Suggesting that the grower experiments by dosing with products aimed at delivering 1 or 2 nutrients is a recipe for trouble. W/o tissue analysis, guessing what nutrient might be deficient then acting on the hunch will be wrong far more often than right. The net result will be a TDS level unnecessarily higher, with no give back, and an increase in the potential for antagonistic deficiencies. The plant's systems are designed to to operate on a full compliment of nutrients in the soil solution. The best way to fertilize is to flush the soil with regularity, thus resetting the fertility level to (near) zero, followed by application of a fertilizer that has ALL nutrients (which normally enter the plant via the root pathway) essential to normal growth, in a ratio that closely mimics the ratio at which the plant actually assimilates the nutrients. This ensures the lowest TDS/EC levels possible w/o risking deficiencies.

    The plant's natural defenses (not protections) are closely linked to it's metabolic rate, so the plant should be encouraged to keep growing (with appropriate amounts of fertilizer as required) except during predictive dormancy. It's easy to control the size of the plant by way of judicious pruning, and that is the appropriate control mechanism, not withholding nutrients which is actually a very dangerous strategy.

    "A tree that isn't growing is dying" ~ Alex Shigo Ph,D

    Al