Hello, We have a fruitless olive tree in a large pot that started getting attacked by some critters this year. We would appreciate any help to ID what could be causing this and how to treat it. Please see attached picture that shows how most leaves look - corners of leaves eaten with tons of black droppings. Thank you. Stefan
There are several pests that will attack Olive Trees. Your best bet is to contact your local county extension office, they will know what pest is most likely to be the problem. http://celosangeles.ucanr.edu/
I am not familiar with olive trees as I live too far north. obviously it is an insect but you need to observe the plant several times a day and maybe even in the dark with a flashlight to catch the offender. first think I would spray is soapy water and clean off any frass and hopefully any pheromones that the insect might be leaving to attract other insects. then you might need to spray an insecticide or even fertilize with one that contains a systemic insecticide that will kill any insects that eat, pierce or injure the plant by consuming it in any manner. the easiest way to wash off the plant is with a hose end applicator sprayer. you add the soap or insecticide to the container and attach it to the end of the hose. that has a stem in it that sucks up the solution and sprays it diluted for you. don't use a hand held spray bottle.
Go to the Dollar store and get a bottle of Sargeants flea shampoo for dogs or spray ! Make sure the active ingredient is permethrin ! Sargeants for cats will work too if you like to stay organic ! Mix a couple of tablespoons with about a pint and a half of water or enough to fill a hand sprayer ! Spray the tree and the potting soil with it ! Does not have to be rinsed off ! The active ingredient, permethrin, is what I have used in my vegetable garden for years ! Soap in the shampoo will hold it on the leaves ! Next time a critter decides to have your tree for dinner he will be standing at the pearly gates !
I found similiar pictures on the net ascribing the damage pattern to weevils. Beetles can be managed in both the grub stage and the adult stage with bT, a very target specific bacillium that must be eaten. Now a new version called BTG is available as a foliar spray where previous versions were used on the soil to stop the grubs. Broad spectrum poisons have the unfortunate effect of removing pollinators, but if necessary, spinosad (also used on cats) is another biological organic product that can be sprayed and is similar to permethrin but made of bacterial toxins that are deadly for some insects. The interesting part of using the shampoo is the sticker action of the soap.
