The problem is less sinister than a disease. It's a common physiological issue called 'oedema'. Oedema is a physiological disorder that can affect all plants. It occurs when the plant takes up more water than it can rid itself of through the process of transpiration. In afflicted plants, internal water pressure (turgidity) can become so high that some leaf cells rupture or the cell contents of cells leak into inter-cellular spaces in leaf tissue. Oedema is most often driven by excessive water retention in the soil, but cool temperatures, high humidity levels, low light conditions, or partial defoliation can individually or collectively be additional contributors, as can anything else that slows transpiration. As well, nutritional deficiencies of Ca and Mg are known contributors to the malady. Symptoms vary by plant, but can include wet or weepy areas on the foliage, blisters that turn from white or tan to dark brown or black, then gradually turn corky/ scaly/ ridged, and wart-like or gall-like bumpy growth.
BTW - the leaf loss isn't related to oedema, but it is caused by the same condition that causes oedema. It's a manifestation of the plant's drought response due to over-watering.
Al
Al
This message was edited May 2, 2015 8:58 PM
