I have a Texas Ash tree whose leaves are turning yellow with brown spots and falling off. Too much rain?
Question:It has rained twice the average amount in the San Antonio area this year and continues to come down. I cannot find any known diseases or insect enemies for this tree online (that's two of the reasons I planted it). However, Texas Ash prefers dry, well-drained soil, so I think the problem must be too much rain.
Answers:
Leaf spots on Ash are caused by a number of different fungi. These diseases can become prevalent in wet years. Minimize reinfections by gathering and disposing of the diseased, fallen leaves. Generally its not life threatening to the tree.
Some possibles; It is possible it is drowning if it is sitting in un-drained water. The roots need air just as much as leaves. Did you use any lawn weed killer near it? Did you fertilize it and add too much? Yellowing might be more in keeping with not fertilizing at all. Nitrogen deficient is yellowing, potassium deficient is brown spotting, and phosphorus deficient can be a purplish color to the leaf especially the veins. If you have done ANYTHING to the tree it is immediately suspect. If you have done nothing then make sure it isn't drowning and if not, fertilize it. If you suspect drowning and it is still a small tree, you can dig a hole as close as you dare so as not to kill roots and then put a pump into the hole and start pumping. Eventually, the area will start to dry. You know what you are willing to do to save it. Good luck.
PS I was not satisfied so I went back to look it up. The tree is the Genus Sorbus. One problem is a borer that attacks the tree near the base/ ground level. That is suspect especially if you have apple trees (flat headed apple tree borer) and a real problem. Also lilac borer. Does it look like parts of the small twigs are burned? Then fireblight. It also gets black rot and rust, and these are shared by apple trees again. The brown spotting could mean cedar apple rust. The cedar, in this case a juniper variety is the alternate host. So there is some more info for you to look at. G'luck.
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