Help with Grapefruit Tree

[Garden_Chris]

Hi Guys,

I've had some troubles with my grapefruit tree since we purchased it in the summer.

It is currently sat in our conservatory (heated periodically when the central heating is turned on). It has citrus compost, a citrus fertiliser applied once per week called 'Citrus Focus Liquid Concentrated Fertiliser 100ml). It is also west facing.

I've noticed some leaves are yellowing, there is an odd liquid running off some leaves and it has barely grown at all.

Is this usual or does anyone have some tips of what I should be doing?

Thanks

[ameno]

Is the liquid sticky? If it is, it will be honeydew, either from aphids or scale insects. You'll want to try and get rid of those, and also wipe off the sticky residue, as it will attract mould.

Otherwise, though, it doesn't actually look unhealthy. Have you repotted it since purchase? If you haven't, it may just be potbound. Best to wait until spring now, though. You should also make sure not to put the plant too close to the radiator, as they don't like dry air.

[Plot70]

It has got scale insects.
Citrus plants can resist them with the help of wind and rain.
What I do is to wait for a stormy night that is not too warm.
The temperature needs to be in single figures but not cold enough for hail. A good Atlantic storm with a yellow wind warning and plenty of rain is what you need. It needs to be cool enough to weaken the grip of the scale insects but not frosty.
Find a spare paving slab and put it in a windy location and chain the pot to it.
Your plant is beginning to turn the backs of its leaves up to face the weather in the hope of getting the insects off by wind and rain.
The leaves don't bruise easily and will take rain drops traveling at 50mph easily.
If your tap water is not too limescale ridden you could use a jet washer.
My citrus from saved seed have only in the last week come in from there summer positions in the garden to the glass topped lean too.

[Snoop Puss]

Great answers, ameno and Plot70. I'm no expert but I was a bit concerned about the yellowing leaf with green veins. But rather than underfeeding, could it possibly a sign of excess feeding if it's being fed once a week? As you say, ameno, the tree looks nice and green otherwise, but for a citrus plant in a pot, might that be a bit too often?

[Jungle Jane]

I can’t see any scale insects or aphids,it might not be that,we don’t know unless we see the insect. Sometimes when a plants been watered too much it’ll excrete the excess water & nutrient through its leaves,it might be that & not honeydew from any insect. Leaves yellow when old & new leaves grow
Edit - I’d water less & wipe the excess liquid away

[Andraste]

Hi Garden_Chris,

Zooming in on your pics, those white fluffy bits make me think it might be mealy bugs that are causing your stick sap leakage. I can't see sooty mold bits which is a good sign that they haven't got too established so you may be able to get away with just picking off the infected leaves to get rid of them. Ladybirds will eat them but you might not want to have those in your conservatory lol.

Although the level of nutrients and watering is always a good call as a cause leaf yellowing, I believe yellow leaves on citrus trees can also sometimes be caused by low temperatures which (especially if given too much water in colder weather). This might also account for the leaves that are drying up - although that could be the mealy bugs' fault too.

[Plot70]

I can see scale insects in top right of the third photo on a leaf stalk and further up the same leaf and one in the fourth photo on the stem with slime on the leaf below it.

[DannyK]

I know nothing about citrus but I have a summer feed and a winter feed.
My two calamondins stay in the greenhouse, which I try to keep at a minimum of 4C.
I had scale on mine and used a systemic. Hosing and exposing to the weather got rid of the sooty deposits.
Mine are just coming into bud.

[mothhawk]

I can see scale insects in top right of the third photo on a leaf stalk and further up the same leaf and one in the fourth photo on the stem with slime on the leaf below it.

I saw those straight away, too, Plot. they tend to hide in the leaf joints and along the veins.

[Plot70]

As well as the two scale insects there is that leaf that looks like it has suffered with some kind of concentrated heat.
That yellow leaf is likely to be something else. There are some types of aphid that inject some kind of toxin into the sap.