Ginkgo tree suffering

Question: Our 30+ year old ginkgo tree looks ill. The lower leaves are yellowed and wilting. A little moss is growing on a few branches.

responder: Best Regards,   Replied June 26, 2023, 6:42 PM EDT
response: Dear Melanie,  Thank you for contacting Ask Extension about your ginkgo tree. It would be helpful to know what type of gingko you have.  Do you know the cultivar? When did the discoloration first appear?   How is the tree watered and how often? Is the tree regularly fertilized?   Yellowing of older leaves or those at the base of a plant is often an indication of a nutrient deficiency, but often this does not mean the soil lacks nutrients. There are a number of other possible causes including over- or under-watering, poor drainage, iron or salt toxicity, or soil pH issues.   Gingkos are also subject to several root-related diseases, however, the pattern of leaf yellowing is not what would normally occur with such problems.   A laboratory soil test would be useful to determine whether there is an imbalance in the soil. However, tests do not usually include the level of nitrogen since it is so highly mobile. If you wish to obtain a lab analysis, here are some links to help you. Included is a list of Oregon labs as well as one other that reportedly caters to home gardeners: https://www.simplysoiltesting.com/ https://catalog.extension.oregonstate.edu/ec628 https://catalog.extension.oregonstate.edu/em8677 https://catalog.extension.oregonstate.edu/ec1478  If you would kindly write back with the answers to the above questions, I will be happy to try to advise you.

responder: The Question Asker Replied June 26, 2023, 11:22 PM EDT
response: I do not know the tree type or cultivar, as it was planted in 1992 when the house was built. The tree has seemed healthy for the 24 years we have owned it. The problem was not obvious when we left Oregon mid December 2022, but was dramatic on our return June 2023. In our absence the tree was watered by rain as we typically start sprinklers in June each year. We have not previously fertilized but usually cover the ground under the tree with its own fallen leaves each fall. This year that mulching did not happen because we hired gardeners in our absence to care for the garden. They used a leaf blower to clear any fallen leaves.  Thank you so much for your help  Sincerely  Melanie Ronai      Get Outlook for iOS    From: ask=<personal data hidden> <ask=<personal data hidden>> on behalf of Ask Extension <<personal data hidden>> Sent: Monday, June 26, 2023 3:42:30 PM To: Melanie Ronai <<personal data hidden>> Subject: Re: Ginkgo tree suffering (#0107362)

responder: Best Regards,   Replied June 27, 2023, 11:13 AM EDT
response: Dear Melanie,  In a case like this, a diagnosis will require the process of elimination of possible causes. I suggest you start with a soil test and a consultation with a professional arborist who can physically inspect the tree. These steps would make it possible to determine whether there may be a nutrient deficiency and/or root problems. The small planting area may be a factor in drainage issues.  Your tree looks like it should be pruned, and that may be another reason to contact a professional. I would caution against beginning any type of treatment before determining the actual cause of the drooping, yellow leaves.   You can locate a qualified professional in your area on the Homeowners tab on this ISA website.  Some will provide an initial consultation without charge:  https://pnwisa.org/page/choosing-a-qualified-arborist  I hope this is helpful. Please write again if you have additional questions. Here are excerpts of an article on root rot that may also help:  Root Rot Root rot is a disease that attacks the roots of trees growing in wet or damp soil. This decaying disease can cut the life short of just about any type of tree or plant and has symptoms similar to other diseases and pest problems, like poor growth, wilted leaves, early leaf drop, branch dieback, and eventual death. Causes of Root Rot There are two causes for root rot, but the main cause is poorly drained or overwatered soils. These soggy conditions prevent roots from absorbing all the oxygen they require to live. As the oxygen-starved roots die and decay, their rot can spread to healthier roots, even if the soggy conditions have been rectified. Weakened roots are more susceptible to soil fungus, which is another cause of root rot. The fungus may be present but dormant in the soil for a long time; when the soil becomes waterlogged, the spores can come to life and attack the roots, causing them to rot and die. Some of the more well-known species of fungi that thrive in moist conditions and cause root rot are Pythium, Phytophthora, Rhizoctonia, and Fusarium. Another notorious fungus is Armillaria, also known as shoestring rot, which causes a lot of damage to hardwoods and conifers in our area. Symptoms and Diagnosing Many symptoms of root rot mirror the signs of a pest infestation, which makes properly diagnosing it more difficult. The symptoms of root rot are obviously easier to spot above ground. Gradual or quick decline without an obvious reason.Stunted or poor growth.Small, pale leaves.Wilted, yellowed, or browned leaves.Branch dieback.Thinning of the canopy.On some species, the fungus grows up from the roots in the inner bark and causes cankers, or sunken dead areas. The most accurate way to diagnose this decaying disease is to dig below ground to see if decaying is taking place. A good tool for this is a Pulaski because it is two sided—one side is for chopping and the other for digging or scraping. A great deal of care should be taken when doing this so as not to cause further harm to the tree. Preventing and Control Tree root diseases are best controlled by prevention. If you are considering planting new trees, choose disease-resistant varieties or cultivars, only plant in well-drained soil, and avoid overwatering. You can also create irrigation moats to keep the water from pooling against tree trunks. Moderately affected trees can sometimes be saved early on by pruning out the infected roots. Always be sure to disinfect any tools you work with before using them again. If a tree is significantly infected, the best way to control it from spreading the disease to healthier trees is to remove it entirely. Chemicals... won’t completely cure the disease but can reduce the level of the infection. These fumigants are applied in and around the base of the infected trees or in holes left after trees have been removed.