Rhododendron leaves turn yellow because of sun exposure, according to the Victoria Rhododendron Society. Sunlight tends to bleach exposed leaves. When this occurs, adding nitrogen helps turn the leaves green again.Know More
The Victoria Rhododendron Society adds that older leaves naturally turn yellow, and they are replaced every one to three years. When the leaves are yellow but the region along the veins remains dark green, the plant likely suffers from chlorosis, which is caused by a magnesium, nitrogen or iron deficiency. In this case, the soil’s pH must be checked. A very high pH hinders the plant's ability to absorb necessary trace metals. If the pH is close to 5.5, adding Epsom salts is a recommended solution. If this does not work, it helps to add a nitrogen source and chelated iron.
Chlorotic leaves are usually a sign of iron deficiency and can be dealt with by using iron sequestrene, according to the Millais Nurseries. Chlorosis is also caused by poor conditions, such as drought, soil pH or drainage problems. Over-fertilizing must be avoided, as the edge of the leaf will likely turn dry and brown. Chicken and farmyard manures are not advisable as fertilizers, because they contain too much nitrogen for rhododendrons. Similarly, bonemeal must be avoided, as it has too much calcium.Learn more about Botany
Fruits turn brown due to exposure to oxygen. This causes the oxidation of phenolic compounds that are naturally present in fruit tissue. This reaction takes place in the chloroplasts by means of an enzyme called polyphenol oxidase.Full Answer >
Bamboo stalks turn yellow when the plant is very unhealthy and dying, this change is caused by a number of factors. Dehydration is the most common reason for a bamboo stalk to yellow. Going without any water for a short amount of time hardens the pores that the plant uses to bring water into the plant. This hardening is permanent, making the plant unable to hydrate itself even if water is added later.Full Answer >
Trees lose their leaves in the winter as they enter their dormant period in order to protect cells from freezing temperatures. In this stage, they no longer need the food that the leaves produce. Trees respond to changes in available light and begin to form a layer of dead cells in the stem of their leaves, so each leaf breaks from the limb and falls to the ground.Full Answer >
Fatsia japonica is an evergreen shrub with white flowers and lobed, leathery palm-shaped leaves that stretch up to 16 inches, according to Great Plant Picks and the Royal Horticultural Society. When fully mature, it grows up to 15 feet tall, according to the Clemson University Home and Garden Information Center.Full Answer >