miyami, it does look like Gummosis to me, which is Foot Rot caused by Phytophthora. You might be able to save your tree, but this looks pretty extensive, sadly. There are treatments you can apply to the trunk to save the tree. Copper based fungicides applied to the trunk, Ridomil Gold applied to the soil as a soil drench (expensive, and hard to find, as it's commercial, but it is treatment of choice). The feeder roots are at the edge of the canopy, don't worry about what you're seeing by digging around the trunk. No, yellow leaves are not normal and have zero to do with our wonderful California sunshine - that should make your leaves green, not yellow :-) Your tree is seriously underfed, and is in need of regular fertilizing at the canopy edge (dripline) of your tree. Use a good quality citrus fertilizer that contains micronutrients. Also, I can't see because your photos are too little, but it looks? like your tree has algae growing on the trunk? That would make me suspect it is getting hit by sprinkers? If so, this is why you are getting a fungal infection on the trunk. Citrus do not like to get hit by sprinklers. You should be drip watering the tree, with 1 to 3 deep waterings a week, depending upon how hot it is (more in the heat of our summers). And, any grass under the tree should be removed, as grass will compete seriously for nutrients, and cause your tree to become nitrogen-deficient (hence the chlorotic appearance). Water is the culprit here. Too much of it, and in the wrong places. Patty S. Here is a link that might be useful: UC IPM: Gummosis

Okay I got the response from the local extension office and here is the diagnosis: "The pictures of actual fruit are showing symptoms of bird damage. Grackles and Starlings will visit the fruit when about the size of a dime and peck, scratch and scar the fruit to cover themselves with citrus oil which serves as a mite repellent. Unless you cover the tree at that time of the year with a bird netting, there is not much you can do. See: http://www.plantanswers.com/citrus_damaged.htm . The brown spots on your apple leaves are caused by a fungus of some sort. Most any fruit tree can be sprayed with Captan fungicide solution. Follow the label directions. Also, even some of the healthy leaves are yellowing, which indicates nutrient deficiency. Several things can cause the symptoms: 1) lack of enough nutrients in the soil; or 2) a root system that is not pulling in the available nutrients because of drought stress, too much water, and competition from weeds/turf grass. Even the fungal spots on the leaves may be worsened by a nutrient-stress issue. First, you may want to check the soil pH and nutrient level by submitting a soil test. Second, remove all weeds/turf grass 18" to 24" out from the main trunk and apply a light layer of an organic mulch such as leaves, dried grass clipping (from grass that hasn�t been sprayed with a broad-leaf weed killer). Third, monitor soil moisture to make sure that the trees are not too dry, nor too wet. Also, dried leaves on a living stem is a good indication of soil/moisture stress. Dried/dead leaves on a dead stem may indicate a canker or gall or wood boring beetle issue. Call my office at 281-342-3034, and ask for ext. 7029 for a soil test bag and form. -Vincent Mannino" The link to the pictures still works if you want a visual summary of my issues. Thanks for the advice....

Imelda, commercial orchardists in Florida (and in all citrus producing states), don't just rely on Imidacloprid. They use a series of various foliar and systemic insecticides to try to manage their orchards. The goal for commercial growers in Florida is to try to keep the trees alive a year or two longer than the average 5 year death rate. Right now, they are rotationally re-planting their orchards, and relying on several pesticides, as well as other measures (such as the one John mentioned - planting less desirable trees around the perimeter of their orchards) to try to stretch out their replacement rates due to death from HLB. The goal for our commercial growers here in California is to kill the psyllid prior to being able to feed on the tree, or incapacitate the psyllid to such a degree, that even if it does begin to feed, there isn't enough time for a potentially infected psyllid (I use the adverb, "potentially" to indicate that we do not have any infected psyllids discovered, yet in California) to inject their infected saliva back into the tree, and thus infect the tree.And, as Steve has pointed out, most certainly would not make it to tree #2, to spread the disease. Also, imidacloprid is a neonicotinoid, and one of the useful features of neonicotinoids is that they are anti-feedants, so psyllids don’t want to feed on trees treated with them. It causes the tree to naturally repel psyllids. Commercial growers have been recommended to apply imidacloprid systemically every 6 weeks, and then use various foliar pesticide applications in between that use different modes of action. Suzi, that is the philosophy behind integrated pest management - use the least harmful management option, first. Only resorting to more intense or toxic management options if the less harmful options are insufficient. You're doing the responsible thing. I was using Spinosad only to treat CLM, but now, I am compelled to also use Imidacloprid as well, since I have over 100 citrus trees on my property, and am adjacent to 157 acres of completely un-managed and abandoned citrus trees that are a giant magnet for all manner of pests. I don't want to use systemic pesticides, as I don't relish eating fruit with pesticide residuals, which is why I grow my own fruit. But, we are in extreme times, and as they say, "extreme times require extreme measures". I am very careful to apply only the recommended amounts and frequencies. I spray my Spinosad in the evening, after the bees have gone back to the hives, and try to spray only after blossom time is over (not always possible with my lemons, as they bloom multiple times). Patty S.

Citrus leaf miner is not much of a concern on large citrus trees. However, on small young trees the miner does cause quite a stress on the tree . Most commercial growers don't bother with controlling the insect on large producing trees.