lime induced chlorosis? soil might be too alkaline - check with pH kit?
it depends where the yellow is - is it old leaves, young leaves, interveinal, veins first, or blotches? all the different answers imply different conditions.
there's a post on this sort of thing about capsicums at rocks riverside park - hang on, i'll go grab it
here - i've copied it over from my reply to Liz Cameron - Anthony Foo had some comments too - the discussion thread is called nutrient deficiency in capsicums - applies to lemon trees too, lemon trees are particularly fussy about pH and about eating a lot - you need to pile on the food (compost/ dynamic lifter etc) and make sure the plant can actually access it (ie pH is around 6-7)
Are the older or younger leaves the first affected? Do you have a photo?
Do you know the pH of the soil? I often find that pH causes deficiencies that right themselves when the pH is corrected.
My guess as to the most likely cause is the general malady called 'lime induced chlorosis' - ie soil is too alkaline (correction is to add plain gardening sulphur dust (not medical quality) - about a handful a square metre) and build up compost and earthworms
Possible other causes could include:
* if young leaves affected first then mature ones, leaves turn brown or start to die where affected, manganese deficiency (try sulphur first)
* if mature leaves are not affected, no leaf tissue death, iron deficiency (unavailable due to pH - try sulphur first)
* older leaves first then younger, leaf margins curled or blotched = molybdenum deficiency (careful, trace element only, apply tiny exact quantities every 10 years).
got this from Permaculture Manual, p211 - excellent key for nutrient deficiencies and how to address , better than all the text books i had at uni studying horticulture
I have a fantastic book called 'All Your Gardening Questions Answered' by Tom Wyatt, that I have been turning to heaps lately. Here is what he has to say about yellow leaves on citrus.
Q. I have planted two citrus trees in my garden and they have gradually deteriorated. The leaves have turned yellow and dropped. The plants try to grow new shoots but they do not develop. I have treated the soil with Condy's crystals and Dettol without result. Can you help?
A. This problem is normally associated with over watering or waterlogged soil. Citrus prefer a well drained soil on the dry side of moist. Reduce your watering and keep mulch and compost away from the trunk of the tree. Saturate the soil around the tree with a solution of copper oxychloride; two treatments, ten to fourteen days apart. Do not water the tree between treatments.
Q. The leaves of my citrus turn yellow and the veins are green. Is too much water causing the problem?
A. No normally green surface mulches cause this problem. The symptoms are of iron deficiency. Apply supphate of iron to the surface of the soil at the rate of one handful per sq metre under the canopy. One application should rectify the problem.
Use blood & bone or neem fertiliser on a regular basis; one handful per square metre every month.
Oh yes and of course, the most obvious: have you fed it recently?
If the pH is fine, yellow leaves probably indicate nitrogen deficiency. Fruit trees need potassium for flowering.
Nitrogen deficiency affects the oldest leaves first, and the whole leaf turns yellow.
Citrus are gross feeders - they like lots of food and plenty of water to bear well.
Personally I'm big on the organic fertilisers (eg dynamic lifter, manure, blood and bone) that build soil structure and biology over time as well giving the plant a feed, rather than those made from petrochemicals that often kill beneficial soil life and need to be applied more frequently. Space food drink vs Sunday lunch.
Still, all your standard NPK (nitrogen/ potassium/ phosphorous) type fertilisers would help if it's just food and not pH.
Also, citrus hate having grass over the dripline. Their roots are not all that competitive for nutrients, even if they are there, and this could be another cause. It's important to make sure that there is no grass over the roots, preferably to just past the canopy diameter. Some ground covers are OK, mulch is even better.
My lemon tree looks shocking. When I moved in in September, I planted half a dozen citrus. They have all come along nicely, with a couple of 'spurts' each. The lemon, however, looks miserable. The leaves have gradually become paler and now have bright yellow veins. Some are starting to fall off. It has not shot any new leaves since planting.
Am I starving the poor thing? Has the fig tree pinched all of its goodies? I have fed all of them up a bit, with dynamic lifter and cane mulch. The mulch has newspaper underneath to stop the grass, but I gave it plenty of dynamic lifter to compensate for the paper pinching nitrogen. I tested pH last weekend, and it should be dandy... a nudge on the acid side of neutral.
(I even have my boys trained to wee on the citrus in turns...)
Pretty sure yellow veins is a mineral deficiency - magnesium from memory but I will check and let you know. I have used epsom salts to correct this in the past but have heard it is not the best method.
Sounds like it's most likely a sulphur deficiency (going on pale and yellowing and yellow veins). Often this is because of pH, but it could have been sucked out by the fig I guess. Or maybe there is builder's rubble under the ground (and an alkaline pH). Try a pH test from deeper down as well maybe.
If it's sulphur deficiency or unavailability (due to pH) the remedy is the same - one handful of sulphur (not medical grade, just normal gardening dusting sulphur) per metre square.
other relevant questions and their indications:
youngest leaves most affected, pale yellowish or white patches on leaves, whole leaf affected including veins plant stunted and spindly - sulphur def: probably this one
youngest leaves most affected, pale yellowish or white patches on leaves, veins or centres still green, leaves wilt then light coloured then die - copper def (unlikely)
youngest leaves most affected, pale yellowish or white patches on leaves, veins or centres still green, leaves do not wilt then die,colour loss interveinal first then veinal, mature leaves little affected, dying not a feature, and common on calcareous or coral atoll soils, desert soils. Distinct yellowing - iron def, try sulphur first, then bury old iron in humus pit near the drip line
areas near veins still green, affected leaf areas become transparent, brown or start to die, young leaves affected first, pH usually over 7 - manganese def. try sulphur first
margins yellow or blotched areas join up. progresses to leaf death. young leaves affected later. growth slow, plant stunted. common on acid soil or soil with high K or Ca readings - magnesium def. Use dolomite, or limestone (not hydrated or agricultural lime - just normal lime). You can use epsom salts near citrus for this too - dolomite probably better. apparently epsom salts will harm soil microbes and fungi, but it will help the plant if it's a magnesium def. This is the other most likely - ie sulphur or dolomite required. Check the pH again for clues and observe which leaves affected first.
interveinal yellowing, looks at first like N def. old leaves blotched, veins pale green, leaf margins rolled or curled, progresses to young leaves - molybdenum (unlikely)
try a liquid feed too in case it's just a nitrogen def. (all leaves light green/ yellow, old leaves go yellow and fall off)
my lime is still miserable after 2 years. it was root bound cos I planted it from a patio pot i'd had for ages. i recently gave it a root prune (radial cuts with a spade) and am crossing fingers it will start to grow properly...
The poor thing was probably root bound... It was about a metre tall in a growbag. Any hope for it? I may need to get more information on the root prune, but will try feeding it up first.
Youngest leaves? No youngest leaves anymore! The ones further down went first, but they are looking uniformly shabby now.
Good tip about checking the pH from deeper down. There is a new shed (probably only a year or so old) which is a few metres away at the closest point. It is on a pretty big slab and would, I assume, lose some lime and stuff (gosh, Amanda) to the surrounding area.
Is there any real danger to feeding it up now in our climate? It is tall enough that frost is unlikely to affect it even if we do get one or two.
When I feed, should I lift up the mulch first?
Should most decent nurseries have the sulphur? I may need to look around again... I finally found one here that smelt right (rather than like a gift shop with plants) but they don't seem to really know that much.
Also, I have a replacement lime and lemon on standby in growbags. I'm thinking of putting them in pots at the entrance to the veggie garden (to look pretty as much as anything). Should I follow the rule of going up in pot sizes as the plant develops, or go straight to big ones? I'm thinking glazed terracotta (pure aesthetics, again... please let me know if there is anything, apart from having to sell off the children to pay for it, against this style).
Thanks again for your wonderful answers Scarlett. You are a wealth of information. Unfortunately though, that just gets me fired up with more questions. :)
Are the sulphur powder the yellow sulphur powder you can get cheaply from produce stores? If so, you can look up a local produce store ~ Their agri-lime, dolomite & gypsum are cheaper then landscapers and nurseries too ~
Hi folks haven't been around for lack of time to check out BLF in detail.......
Having said that lets look at some facts...........
Firstly Epsom Salts............................
This product is in fact 100% Magnesium Sulphate, it is a salt that is the product of reacting a Base like Magnesium Hydroxide with Sulphuric Acid. And therefore Epsom Salts are by nature salts and water soluble. Adding salt based fertilizers to soil provide an immediate substrate for plants to take up and use as fertilizer but, leaves nothing behind for plants to use in the future, it is good for a quick fix especially if soluble fertilisers are not commonly utilised by the gardener, and realistically some soil held sodium is required for good electroconductivity or paramagnetic conductivity of the soil (or in living beings of the nervous system and cellular structure)..
if this action of adding a little Epsom salts is not backed up by adding gypsum (lime and magnesium) which in most cases should be in a ratio of 3 parts lime to 1 part mag, the plants are left needing
Note... It is true adding high concentrations of salts to soils kills beneficial soil organisms that fight off disease, decompose soil elements that will end up feeding the plants and a host of other properties and tasks, but so to the microbes need a little sodium and so little bit little bit is not harmful to your precious microflora......
As for citrus in general as stated by Donna and Scarlett, they are gross feeders feed them up good compost is the best as always, if you are mag deficient feed dolomite if you are sulfur deficient feed gypsum.
If its an N deficiency your dynamic liffter might well look after it but to speed up the process add a small amount of fish or NPK fert high in N. Also fish will feed your fungi and mollasses your bactieria (microflora)
If the root ball is unable to break free of its self you are better to lift the plant and as Scarlett indicated give it a good root prune or in other words break up the root ball, in the compact state a root ball will not only end up in dead or stunted trees but will likely be impervious to moisture (water replant) break it up soak it and then replant it soak it into the ground and lightly feed it and prune folage back to help overcome shock.........
Amanda in answer to your question about pot size go as large as possible as the trees will like you a whole lot better and you will achieve better cropping.
My "lots-a-lemon" dwarf in a large pot is also looking rather sad, after a nice harvest of 5 huge lemons - no flowers, and leaves yellowing. The gardening person at Bunnings told me that I should tip the plant out of the pot every year, give it a root prune and change the potting mix! A big job... and expensive... good potting mix doesn't come cheap! I have a big bag of Dynamic Lifter - can I just mix that and dolomite into the old potting mix? Here's a pic of the plant while it was still looking nice.
Never heard of replacing the potting mix yearly! Personally I would give it a good fertilise and compost if available (and some minerals if not included in the fertliser for the yellow leaves depending on what part/ type of leaf is yellow) and see how I go...
I would also only root prune if it was getting to big for the pot (see Anthony's advice above if you decide to root prune) and you wanted to keep it in that size rather than move it to a bigger pot.