Is this serious?

thanks for trying to help citrus joe - -

>Sunlight....photo-period - - gets full sun light, no shade

>Moisture....too much, too little - the only problem has been that weelend where we had over a metre of rain in a couple of days - thought there wasn't any sitting water where the tree is. The trees get a good watering once a week.

>Herbicide damage....is it possible or not? - no herbicide has been used since I moved here - 5 years ago and the tree was planted about three and a half years ago. none has been used by any of my neighbours

>Root or stem damage? - none that I know of

>Fertility levels....too much, not enough? - The site used to have a couple of pencil pines growing there - they were chopped down and about 12 months later the lemon was planted - -in the same area is a valencia and a seedling grapefruit - no visible signs of damage. The orange and lemon had a bad leaf miner attack about six months ago - all infested leaves were removed and the trees fed with fish emulsion (each tree lost about one eighth of the leaf cover)

>Compaction? none - soil is pretty good after all of the mulch

the leaf miner may have been what caused the stress - - ???

Leaf miner...maybe but I doubt it. I saw it in Texas last fall but have never dealth with it personally....maybe some other CN members can give us some insite? Buddingman2 would know....Bonnie??

One of the most common effects of bark diseases, especially diseases of the trunk, main branches, and upper part of the main roots, is to stimulate gum formation, and this has led to the use, by growers, of the general term "gum disease." Exuded gum is one of the most conspicuous features, and one of the first noticeable symptoms, of several bark diseases; but gum formation itself is not a serious handicap to the tree unless the bark dies or the gum plugs the wood vessels. The gum is merely a resultant, and may serve a useful purpose in flooding the tissue ahead of certain invading parasite and slowing down their progress . Frequently, gum forms near the cambium under the live bark for considerable distances, six inches to a foot or more, beyond the margin of the tissue actually invaded. The presence of exuded gum alone is not a good diagnostic character, since its appearance and form are usually much the same in a very large number of different diseases and its amount depends on a number of external and internal factors such as temperature, air humidity, physiological conditions of the tissue, etc. Gum formation, while commonly caused by invading organisms, is not always due to the stimulus produced by invading organisms, but may result from irritations of chemical or other stimuli. Where organisms are not involved, the gum formation is usually temporary, but may frequently be mistaken for that produced by invasion of organisms. Gummosis is also commonly caused as a result of the organism Phytopthora, especially in citrus. If so, in your tree's case, here is a chemical commonly used for control. One note of caution, the chemical is systemic in nature, therefore should not be use on a tree while it is bearing fruit.


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thanks Newton - excellent info and comments

I won't be using the systemic chemical - an aversion to anything chemical in my garden...

is the Phytophthora the same fungus that attacks grape vines? I grew a grape vine near to where the lemon was eventually planted so that may be the cause....

Phytophthora affects a very wide range of plants, grapes included. Gumosis in citrus can result from a large number of different diseases, not just phytophthora. The problem can be serious if the bark dies or the gum plugs the wood vessels. I doubt there is a connection with the grape vine. It is not wise to apply mulch under a citrus tree. This is especially true near the the trunk base, as mulch creates a moist condition favorable to phytophthora, fungi in general, and invading insects.