Hi, here in Spain we have a newish problem with the so-called worm which is said to come from Mexico. I'm not sure it really is a worm as such, but it basically attacks the leaves, deposits lots of damaging spots on them, and hence turns them yellow. They don't drop off, and the fruit don't seem to be affected. Any knowledge of this would be appreciated, especially I guess from the Americas, which would be more likely to be affected by such a parasite than here in Europe. Thank you! :-)) Lu
It sounds like Avocado Leaf Miner, which is fairly common in South America. I use horticultural oil to control it on my avocadoes - it's similar to Citrus Leaf Miners, and responds to the same treatment.
Hi and thanks for your replies. I'm attaching a photo for you to see one of the leaves (if it's worked!) -look familiar? How does one tell if there are miners or mites? I can't see any live beasts on the leaves or branches. And what is horticultural oil and how do I use it? Thank you again!! Lu
That's not miners. It might be spider-mites, in which point you won't see the actual critters, but you will see fine webbing on the tree, something like spider's webbing but much finer, more like the cobwebs that you find in the high corners of your ceiling. Horticultural oil is just what it sound like - a sprayable oil that won't hurt your trees. Most garden centers carry it; another option is olive pomace oil, which works in the same fashion. You're in Andalucia, so that might actually be a cheaper alternative; I know that here in Ecuador it's prohibitively expensive. Oils are used by spraying them onto the tree around sunset, and allowing them to work overnight. I say this from experience - I live in an area that is comparably sunny to Andalucia, and if you oil a tree in the daytime you run the risk of sunburning the leaves, which is counterproductive. Your other option is to try an insecticidal soap - you can make this yourself using about 10 drops of neutral, non-scented liquid dish soap, a few drops of oil of oregano, and about a gallon of water. Shake well and spray the tree thoroughly, making sure you get underneath the leaves. This can be done in the daytime.
