Ask a Question forum→Cause of leaf yellowing on grapefruit

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Northern California
New_to_this
May 21, 2020 8:21 AM CST
The leaves on my 2-3 yr old grapefruit are yellowing - I can't tell if this is due to overwatering, sun scald or other. They're in containers in a citrus mix that is well draining. Attaching a few pics - appreciate any advice.
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Name: one-eye-luke US.Vet.
Texas (Zone 8a)
Quitter's never Win
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oneeyeluke
May 21, 2020 1:24 PM CST
How do you add fertilizer to your plant, and what kind?
NOT A EXPERT! Just a grow worm! I never met a plant I didn’t love.✌
Northern California
New_to_this
May 21, 2020 1:51 PM CST
I've applied a Soluble citrus 24-14-14 fertilizer made by Romeo (https://www.fourwindsgrowers.c...), diluted per manufacturer instructions. This has been applied twice since purchasing these trees ~5 weeks ago - watered in deeply (instructions say to apply at the prescribed concentration every 10 days, but given I recently transplanted then into new containers, I wanted to give them time to settle and not over-fertilize).

Also I should note that there has been no leaf drop, and some of the under leaves are retaining their green while the largest and upper leaves are the ones yellowing the most
[Last edited by New_to_this - May 21, 2020 3:30 PM (+)]
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Name: Daisy I
Reno, Nv (Zone 6b)
Not all who wander are lost
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DaisyI
May 21, 2020 8:01 PM CST
Too much fertilizer!

Did you read the label on the citrus soil bag to see if it already came fortified with fertilizer? That is very common.

Citrus trees should be fertilized 3 times a year, starting in their second year. The fertilizer should be mixed at 1/4 to 1/3 the recommeded strength.
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and proclaiming...."WOW What a Ride!!" -Mark Frost

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Name: sumire
Reno, Nevada (Zone 6a)
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sumire
May 21, 2020 8:03 PM CST
I have six potted citrus.

I love Fourwinds but their suggestions for fertilizer are a rather high. I only fertilize once a year. They are always covered in flowers and fruit.
www.sumiredesigns.com
Northern California
New_to_this
May 21, 2020 8:08 PM CST
@DaisyI, the soil has no fertilizer, and these are 2-3 tree old trees. The fertilizing instruction says to apply at this diluted level every ten days, so I've gone lighter than the instructions...

@sumire, given they are a reputable nursery, I assumed I should follow their instructions and recommendations on fertilizer... Confused
[Last edited by New_to_this - May 21, 2020 8:09 PM (+)]
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Name: sumire
Reno, Nevada (Zone 6a)
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sumire
May 21, 2020 8:48 PM CST
Hmm... I think there are a couple of layers to this one... Please bear with me because this is a longer explanation.

Do I have all the facts correct?
The trees themselves are 2-3 years old, but you have only had them for about 5 weeks. And they came potted. (I checked and it looks like the grapefruit do, but I got mine bare root from them.) And you repotted them in new soil that is NOT amended but is citrus soil.

When you repot a citrus tree it will typically take at least 4-5 months for the tree to settle in well, during that adjustment period I expect to see a certain amount of leaf yellowing and fruit drop due to stress. Moving to the new climate of your house will probably slow that down too. (Not to mention the shipping stress.) After that, the tree will begin to grow properly again. If the soil was amended it usually takes about a year for the fertilizer in the soil to be used up.

Watering problems usually show up pretty suddenly when the leaves simply fall completely off. Yours have not and "watering deeply" sounds good, so I am going to assume that part is fine.

It is very, very hard to kill a citrus with under-fertilizing and it takes a very long time. The leaves slowly pale, become blotchy, reduce in size and the growth stalls.

Romeo's fertilizer is very strong, at the listed indoor/potted plant concentration I would expect the trees to be in full fruit and very heavy growth. Yours are not. At two to three years old they are just old enough that they MIGHT crop and are still in their adjustment period. I do not think they can currently handle the fertilizer strength.

And truthfully, I always tend to under fertilize. I have discovered that it does not effect the ability of my plants to crop well, but does cut down on some of the bug problems because the trees do not flush out with so much green juicy growth every chance they get. (Mine are in a greenhouse, so I have to watch everything very carefully for developing bug problems because they spiral out of control quickly.)

I would advise simply not fertilizing for a couple of months and watching your plants carefully. If they start to look worse, bring more pictures and we can work it out. There are many citrus experts on this site! If they start to look better, you can slowly add in fertilizer in about 3 months. (Start with one dose at 1/4 strength, and then wait. It only takes about a week for citrus to show the effects of feeding.)

I hope this is a better explanation. (If not, ask me more questions and I will try again!) Smiling

www.sumiredesigns.com
Northern California
New_to_this
May 21, 2020 9:06 PM CST
@sumire, thank you very much for taking the time. You got it all correct; I bought 2-3 year old trees from four winds which came potted and I transplanted them ~5 weeks ago and I used EB Stone citrus and palm mix which has no fertilizer in it - it consists of aged fir bark, lava rock, sand, volcanic pumice, aged redwood, and peat moss.

With regards to the Romeo fertilizer, I did use a slightly diluted version vs their instructions, and the second application a week ago I applied 6 cups of the fertilizer water to a 5 gallon soil container, after which it rained later that day, so I presume some of the fertilizer washed out from the rain. Net net, I don't _think_ that's a super heavy quantity of fertilizer? but perhaps you're right I just shouldn't have applied any in the first place. I also hope you're right the yellowing is mainly stress from all the change, but as they say hope is not a plan Smiling

Appreciate the response and I won't add any fertilizer for a few months to see how things go. Thank you!
[Last edited by New_to_this - May 21, 2020 10:44 PM (+)]
Give a thumbs up | Quote | Post #2247157 (8)
Name: sumire
Reno, Nevada (Zone 6a)
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sumire
May 21, 2020 9:34 PM CST
Keep us posted!
www.sumiredesigns.com

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