Mandarin bark problem

EvesGarden says...
Sorry, somehow the text in my post and one photo got lost in inter-space...
I am fairly new to growing citrus. This mandarin tree was here when we moved in about a year and a half ago. I noticed a wound in the bark when we first moved in, and the rust colour on it. I thought maybe it was from a whipper snipper and the bore water. The previous owner used bore water, but the retic broke, so I've been watering with tap water for over a year.
The leaves look healthy, and the tree puts out heaps of blossoms, but almost no fruit grows.
I just noticed the bark has peeled away a lot more from when I first noticed it, and seems to be spreading. There is no oozing gum or black spots. Can anyone advise what is wrong and how to treat it? Thanks for any input!

Pictures - Click to enlarge
Picture: 1

Fruitylicious1 says...
Hi Eves

Looks like your manda tree is suffering from bark sunburn. Normally, Citrus trees are bushy and most of the trunk is covered with stems and leaves to protect itself from sun scald. I can see from the images that the lower part of the trunk was heavily pruned maybe by the previous owner exposing the lower extremeties to the hot Perth summer sun especially during prolonged heatwave in summer.

To correct this problem, carefully remove all loose and dead bark up to the end of the healthy tissue. After scraping all the the dead skin paint the exposed area including the whole lower trunk with water based white house paint diluted with water. Apply at least a double coat to protect the limbs from further sun damage including pathogens that might try to enter the exposed wood and under the edge of the healthy bark.

I can also view from the latest picture that there's a plenty of weed near the base of the tree. Remove all the grass within 2 meters from the base of the tree and mulch around it to suppress the weeds and help retain moisture around the tree

Citrus trees are heavy feeders. For a mature tree like yours you need a minimum 1-1/4 kg of fertilizer 3x a year (July, Nov, March). Don't apply fert during flowering or it will drop the blossoms. Apply it when the fruitlets have formed. Pelletized chook poo is best mixed with sulphate of potash. So your manda is due to be fed next month March. Apply the fertilizer along the drip line under the mulch so when you water or when it rains the fert stays in place and doesn't get washed away. Also apply epsom salt if the leaves turns to yellow in color especially after winter.

If you irrigate and fertilize your manda consistently you will be rewarded with plenty of sweet, mouth watering and succulent fruit every summer.

Kindly disregard my first advise to you coz i haven't yet read your narrative and i haven't seen the 3rd and most important picture when i made those comments.