Hi everyone. I live in Western Sydney, and have a HUGE olive tree in my back yard, which is about 4 meters high, and get lots of sun light. I dont know how old it is as it was already there when we bought our house 3 years ago. For some reason, this tree never gives any olvies, it never flowers and constantly has mostly yellow leafs. However, there are constant new smaller branches spurting from the bottom part of the tree, which a rich green in colour, but the rest of the tree is yellow. I water the damn thing (not much to avoid root rot), i give it nutrients (thrive soluble, thrive 4 in 1 granuals, miracle grow) and other plant food. I was told by a local nursery that i should give it lime, which i did. Then i was told to test the ph of the soil, which turned out to be spot on. The i was told to give fertilizer, which i did to no success. I have tried blood and bone and everything else i can think of. It is on a flat land and has good drainage. I am lost as to what i can do to make this tree work. I was about to chop it down on the weekend but i thought i will give this site a try. Anyone have any info which may help or have come across this issue? Thank you.
07 July 2019 02:50 AM
This sounds like a sad old tree! It may be that the tree was a seedling and simply has never flowered or set fruit very well. Without inspecting, it is hard to say whats wrong that is causing the yellowing but it sounds like the tree could have root problems of unknown origin. If pH is ok and fertilsers don't help (never fertilise if soil is dry or plant stressed in any way) then I would just stick to fortnightly applications of seaweed extract (like ecoSeaweed) to roots and foliage until late spring. You could mix some sulphate of potash in the same solution (monthly)to build immunity to diseases and also encourage flower production. Check the leaves for symptoms of cercospora leaf spot - Lesions at maturity are 1/8 inch in diameter and appear light gray-colored to dark tan with a brown to purple border. Severely affected leaves wither and die from coalescing lesions. A diagnostic feature is the presence of tiny black dots (pseudostromata) that form in leaf substomatal cavities within the grayish-tan lesions.
If this is present you will need to spray with a Yates Leaf Curl Copper Fungicide Spray spray in late autumn (preferably before winter rains)and again as fruit changes colour (if it sets any). I really need to see a picture to help any further.