AboutJohn Cawly Expertise I can help with identification and possible treatment of plant diseases that affect houseplants and horticultural species, to include both biological (fungal, bacterial, viral, parasitic etc.) and environmental/cultural (watering, potting media, etc.) aspects.
Experience Practical experience with a wide variety of houseplants and greenhouse plants, including cacti, euphorbia, african violets, amaryllus, and many others.
Organizations American Phytopathology Society
American Society of Plant Biologists
American Society for Virology
Publications Molecular Plant Microbe Interactions
Proceedings of the National Academy of Science (in print)
Rhodora -- Journal of the New England Botanical Society
Allelopathy Journal
Education/Credentials BS, Southern Illinois University - Biological Sciences MS, Southern Illinois University -- Biological Sciences - Genetic Engineering Specialization PhD, University of Missouri Columbia -- Plant Microbiology and Pathology (Viral Diseases specialization/Biotechnology Emphasis)
New tree planted one year ago on ocean 20 mi south of San Francisco. It gets southen exposure and somewhat protected from the salty wind as the house is a barrier. Good growth, nice green color of leaves with occasional yellowing of tips but regains color. Some of the leaves are curled at tips. After this first rain, most of the leaves twisted themselves bottomside up. Soil surrounding the plant ball area that was not amended has clay in it. The soil retains water and we are at the lowest point on the street with a big hill behind us. It gets watered only about once a month but more in our Indian summer. Also area near tree has a full plastic weed reduction barrier covered by "gorilla hair". Area around tree the plastic is cut away by 18". I have fertilized once about 3 months ago with dry pellets. Now have several blooms and lemonets on lower branches.
Question: Should I be concerned about the leaves turning. Does it indicate something pathological?
Thank you very much for your time!
Leah Champion
Answer Hi Leah,
First of all, if only a few leaves are affected and it is only an occasional occurrence, then I would not think that it is anything pathogen related. Since you describe you soil as clay, there is the possibility that drainage is a problem after rains. Leaves can curl in response to overwatering, and the leaf curl is usually upward, exposing the underside of the leaf.
Leaf curl is often evident in late fall/early winter; the leaves curl downward.
If the leaf curl is associated with overwatering, then when soil moisture returns to within normal ranges, your leaf-curl symptoms should disappear.
At this point, there are no indications that what you describe is pathogen-related.
