Avocado leaves burning - what gives?

[pniddy]

I bought three avocado trees (photos here: http://imgur.com/a/I2FNA ) about two months ago - two seedlings and a grafted tree. I planted them in plastic pots using Tree & Shrub garden soil + fertilizer with perlite, and sprinkled on a small amount of 10-6-4 Citrus and Avocado Food when I first planted them (About 1 tablespoon for the seedlings and three for the larger grafted three.) I've kept them moist but not over-watered by watering lightly every three days or so. They've been kept inside for the most part to avoid the heat and sunburn.
They all seemed to be doing fine at first, but the leaves on the seedlings started to burn a bit about a month in. Then things really took a turn for the worse for one of the seedlings; it's as good as dead now, and the other isn't looking great either.
What's really concerning now is the larger grafted tree has started to develop brown leaves. Just a few at first, and now it seems to be getting worse by the day. I'm so perplexed about what the problem could be. I've read everything I could find about the potential problems and it seems like all signs are pointing towards salt accumulation. But is that even possible, given that I've only used tap water, and probably watered them a total of 10 times? Could it be a problem with too much fertilizer? And if it is a problem with salt or fertilizer, how should I remedy the problem?

[bsbullie]

Here are the issues I see:

 - you never want to use a potting mix that has fertilizer incorporated into it.  That can and usually will burn the roots, which can cause major issues with the trees.

- keeping them inside is not an ideal place...it is actually less than ideal.  They need to be outside.  Not sure where they came from but they were most likely grown in the sun or under a minimal shade cloth.  They should be slowly acclimated to full sun.

- depending on the potting mix, they may need more water than what they are getting.  Not sure if you are or not but if you have a saucer under the pots to catch the water, that is a no-no.  Avocado like to be watered, they just dont like to have their roots sit in water or stay wet.

- Avocado/citrus fertilizer is not really the best fertilizer to use, go with a high quality palm fertilizer,  It will have a better minor element package.

My biggest concerns are the fertilizers that are incorporated into the potting mix and the fact that they are indoors.

[pniddy]

Thanks for your quick reply Rob. I brought them indoors after reading that they would be sensitive to sunburn. The grafted tree is getting about 3 hours of direct sun through the window. It's also been very hot in South Louisiana. I can put them back outside but do you think it's advisable to put them in full sun?

As for the soil with fertilizer, I just read the back of the bag, and the percentages of PNK are less than 0.1%. It also says "This product is a low analysis fertilizer. Not for use as a fertilizer product." Do you still think it could be a problem?

I don't have a saucer under the pots and have been pretty cautious of over-watering.

Do you think the water I'm using could be a problem?

[treefrog]

fertilizer issues come to mind.  the ferts included in your potting mix, or ferts added later.
read the label, and watch for chlorine.  west indian varieties are more tolerant than mex or guat varieties, but none of them really like salt.  chlorine is often the worst offender.  in your ingredient list, look for chlorine, chloride, or muriate.  these are all names for chlorine.  muriate of potash is potassium chloride.

i find it helpful to use a very light hand on ferts, but do it more often.   a quarter (or less) the reccommended application, twice as often.

[shaneatwell]

If you're talking about tip burn...my trees have all developed serious tip burn after acquiring them. As in they burn, drop leaves, flush, burn, drop leaves etc. But after two seasons my first two trees are looking fantastic and have broken the cycle. Might be avoidable, but also might not matter in the long run.

[barath]

If you're talking about tip burn...my trees have all developed serious tip burn after acquiring them. As in they burn, drop leaves, flush, burn, drop leaves etc. But after two seasons my first two trees are looking fantastic and have broken the cycle. Might be avoidable, but also might not matter in the long run.

Same here.  One other thing that has helped get rid of leaf tip burn in the same season is a bit of elemental sulfur and a really heavy watering.

Though the pictures posted above seem to show more than just tip burn, which definitely could be due to fertilizers.

[pniddy]

Would it make any sense to re-pot the grafted tree with less fertilized soil? The situation is looking worse every day.

[barath]

I've dug up Avocados (when forced to), and it's sometimes worth doing to save a tree.  Try to be very gentle with the rootball because the roots are pretty fragile.  You might wash off as much of the soil that clings to it and directly plant the tree in unamended soil in a different location, and give the tree a light mesh shade cloth so that it doesn't cook as it adjusts to its new location.

Edit: sorry, I forgot your plants are in pots -- in that case, even easier...

[bsbullie]

I've dug up Avocados (when forced to), and it's sometimes worth doing to save a tree.  Try to be very gentle with the rootball because the roots are pretty fragile.  You might wash off as much of the soil that clings to it and directly plant the tree in unamended soil in a different location, and give the tree a light mesh shade cloth so that it doesn't cook as it adjusts to its new location.

his trees are in pits.

[bsbullie]

Would it make any sense to re-pot the grafted tree with less fertilized soil? The situation is looking worse every day.

How long have they been in their current pots?  If you can remove them with the original root ball undisturbed,  you will haveno issues.  Before you do aanything,  make sure you have new potting mix on hand.  Look for Fafard or ProMix for best results.   Just be s ure you are getting the commercial grade, one with no fertilizer added. 

[pniddy]

Ok thanks, I'll give it a shot. It seems like the original soil is still in tact, so it should be pretty easy. Really appreciate all your help.

[WaterFowler]

I live in Palm Springs, so I'm in an area even hotter than you. I have about 30 seedlings that I set out this spring from probably 4 or 5 different types of avocados. Of those only 3 shows virtually no leaf burn. I don't remember which type of avocado they were from but all three look very similar so I'm guessing they are the same type. The rest are living but barely, most are just long stems with a few burnt leaves on them now. They all looked good until it got hot. I have them under 60% shade, with only the first hour of direct morning sunlight but they still suffer. They are all in pots and bags. I been meaning to trash most of them but keep watering them every day for some reason.

Extreme heat just seems too much for avocados, my lychees and cherimoya seem to be suffering too. But my mangoes, Sapodillas, guavas, soursop and star apples all seem to be doing fantastic. I have fan in ground Haas at my renters house that looked like crap after the first 2 summers and I thought for sure it would die but it's looking pretty good this summer so far and we are halfway through August. 

[SamiC]

This happened this past week after some seriously hot 100 degree weather. I'm kind of stuck as what to do now. Do I yank the tree and start over or can I fix it?

[SamiC]

BUMP!! Don't want to start a whole new thread about avocado leaf burn.

[Mark in Texas]

This happened this past week after some seriously hot 100 degree weather. I'm kind of stuck as what to do now. Do I yank the tree and start over or can I fix it?

My avocado trees just started the same thing and I think its the heat which is near 100F or better every day.  I'd flush with rainwater if you have it and hope for cooler weather.  They may be in a cycle of normal necrosis with an impending new flush of foliage about to happen.

[SamiC]

Real bummer, it had just put this flush out and now it's all for naught.