The grapefruit tree in question has oozing sores all over the bark of the main trunk, and the ooze dries in amber-like clumps. The sores are localized to the trunk (all around) and not to the branches. The tree is still producing healthy fruit, but the leaves are yellow and a little thin, which indicates to me that the tree may be nitrogen deficient. Why is the tree oozing, and how can I help it out? The ground as been covered with a heavy layer of white gravel and some mesh, which I recently pulled up and replaced with a small raised bed full of compost. Will this help? It has been suggested that the tree has been sunburned, or that the tree is suffering from frost damage from a frost a year or so ago, but neither of these explanations are entirely satisfying, especially because I don't know what to do. also, knowing that the grapefruit is shallow rooted, are there any good companion plants to grow under the tree or perhaps a climber to cover the bark? Thanks so much
Covering roots of a shallow rooted (or any) tree with a raised bed of anything is asking for trouble. It's keeping oxygen out, holding water too long (compost can stay wet a long time) in there and possibly introducing unwanted stuff (chemicals, etc.) to the soil. It's not clear whether the problem started before or after the bed was made, and the gravel was a mistake as well, but if you can have a knowledgable 'tree' person look at the damage to see if it is from insects or whatever, it would certainly help to decide where the problem lies.
The oozing sap could be a symptom of gummosis - a condition caused by infection by Phytophthora fungi.
Junglekeeper could possibly be correct. On the other hand, oozing of sap on citrus is not all that uncommon. Many times there is no particular known cause that can be identified. The oozing frequently does not last very long, clears up on it own without any noticeable harm to the tree. - Millet
I put the very shallow raised bed around the grapefruit after the trouble on the trunk showed up. I put it there because the tree was nitrogen deficient. Will the stuff hurt the tree?
What does a raised bed have to due with a nitrogen deficiency? I take it that the tree was already planted in the ground. If so, then raising the soil level onto a citrus tree's trunk is not a good idea. . A properly planed citrus tree shows a little of the roots near the trunk. Raising the soil level up upon the trunk can cause problems.. - Millet
Do you see this on some varieties more so than others? I've often noticed oozing of sap on Nagami kumquats and concluded (perhaps incorrectly) that these were trees to be avoided. Is there a way for the untrained eye to distinguish between these two types of oozing?
The dirt in the raised bed is about four inches high, and the organic mulch stuff added is high in nitrogen, among other nutrients; I guess I could have made a compost tea instead? My reasoning was: The tree roots have been covered with a bunch of gravel and mesh for a few years, and I put down the stuff because I was afraid that suddenly exposing the covered ground might open the roots to an infection. ...are there any good companion plants to place around citrus?
EDrisko, the area around the base of citrus trees is best left bare. The addition of companion plants, mulch, grass, rocks, additional soil, organic compounds of any type are never recommended. Because citrus are very heavy feeders, fertilizing with organic nutrients is marginal at best. Certainly organic grown citrus produce much smaller crop loads than trees that are grown conventionally. As you are an organic grower, this is more than likely the reason your tree is showing symptoms of nitrogen deficiency, and surely must have a deficiency of potassium, as an adequate level of potassium is the most difficult nutrient to supply organically. Therefore, if you wish to grow the tree using organic gardening methods, you must be constantly vigilant to the trees requirements. Actually, the tree "itself" cannot tell the difference between conventional nutrients and organic nutrients. Nitrogen is nitrogen is nitrogen, and the same goes for the other elements. I certainly am not against organic culture, I'm just advising you that you will need to feed more often, and be much more observant of deficiency symptoms, also keep any organic fertilizer (or anything for that matter) at least 15 inches away from the tree's trunk. Lastly, keep an eye on your tree. One of the most common effects of diseases of the trunk, branches and stems, is the stimulation of gum. Gum formation itself is not a serious problem to the tree unless the dark dies or the gum plugs the wood vessels. According to the book "The Citrus Industry" gum formation serves a useful purpose in flooding the tissue ahead of any invading parasites and slowing down their progress. Where organisms are not involved, however, the gum formation is usually temporary, but is frequently mistaken for that produced by the invasion of organisms. - Millet
Hi Junglekeeper, there are some varieties that are resistant to some of the gum diseases, such as sour orange, trifoliate orange, Cleopatra mandarin, rough lemon and some of the Citranges. Visually, exuded gum is not a good diagnostic symptom of what a problem might be, because it appearance looks the same in a large number of different diseases. - Millet
Millet, I had to reread your replies several times. Just to be sure I'm understanding this correctly, you're saying occasional oozing is normal AND is not necessarily a sign of disease?
