I have two semi-dewarf citrus trees. One is lemon and one orange. I do not remember which is which. I have not seen any fruit on them, only abundant flowers. And, there are no tags. They were planted three years ago. Booth trees are diseased. Here is picture of Tree#1Healthy. Following are three other pictures.
Reddaddy
Tree#1Diseased. Plese note the small web nest on right.
Tree#2Healthy
Tree#2Diseased
One additional point. Tree#1 is swarmimg with ants. Tree#2 has none.
I took the two damaged leaves to a nursery. I was told that Tree#1 (probably the orange) has leaf miner and Tree#2 has an undetermined disease. It was recommended that I spray them both with malathion and another pesticide. Are there natural methods of treatment that I could use in place of these pesticides?
I'm not a citrus grower, but I believe neem oil works on the citrus leaf miner.
Here's some info from UC Davis on controlling the leaf miners. http://www.ipm.ucdavis.edu/PMG/r107303211.html I don't see malathion on their list (although maybe I missed it) but I would take their word over the nursery (especially since the nursery was advising you to spray pesticides on the 2nd tree when they don't know what's wrong with it). The last thing on UCD's list is azadiractin, which is the active component of neem oil, so you could try an organic insecticide with neem in it. But it's the last one on their list which they say is in order of effectiveness so you will probably have better luck with one of the others. I have a feeling they may be a bit tough to get rid of--the UC Davis site typically doesn't recommend nasty chemical approaches to things when there are more natural insecticides or biological controls that will do the job, so the fact that they have chemical pesticides at the top of the list on this one tells me that they may be challenging to get rid of.
I have a lemon and a lime tree in my yard that are both infested with "citrus leaf minor", a new pest to Ca.,and the ants farm the mealy bugs. I also have "citrus silver mites on my lemon. While these make the fruit look ugly, , they have NO effect on fruit production, at least for me. I would suspect soil or weather problems. One of my neighbors is getting no fruit on her lemon, and asked me about it...when I looked at her tree, it was shaded out by a row of tall cypress which also have very invasive roots. I don't know if that is the problem, but it is something to consider. I have tried neem oil on my trees, with no luck. Maybe I wasn't diligent enough, but I think it only works on the adults, before they lay their eggs under the leaf tissue. In other words, a contact spray. Hope this helps. I'd like to know how to get rid of them too!
Carol
wcgypsy, thanks for the sugestion. ecrane3, thank you for the article. Carol, thanks for your experience.
I will avoid malathion. I will try neem oil on my orange, and if not successful, move higher on the UCEIPM list. Any suggestions as to how to find the specific disease on the lemon?
You might try the Garden Pests & Diseases forum here. If nobody there has any ideas, then I'd find your local extension office and see if they can figure it out.
To continue this thread, please go to Garden Pests and Diseases, topic "Lemon Disease".
Reddaddy
