The Nellie Stevens holly tree (Ilex x attenuate) is a cross between the English holly and the Chinese holly. The tree is favored for its broad, dense, pyramidal shape with dark green foliage. The tree blooms with small white flowers during spring, which make way for bright red berries. Nellie Stevens adapts well to a variety of environmental conditions and has a high level of drought resistance and shade tolerance.
Botryosphaeria canker or bot canker on Nellie Stevens holly tree is caused by a number of species of the Botryosphaeria fungus. The disease causes the cankers on the branches and stems of the tree leading to browning of leaves and gradual death of the tree. Bot canker commonly afflicts the weaker plants. The earliest symptoms of disease include a sudden browning of foliage and the failure of affected branches and twigs to bear new leaves. The best control option includes reducing environmental stress on the trees and ensuring that trees are healthy. Care should be taken to avoid root, stem or branch damage.
Iron chlorosis in Nellie Stevens tree leads to a uniform yellowing of the foliage. Iron chlorosis has a number of causes including root damage, nutritional deficiency, careless use of herbicides, lack of or excess water to the tree and exposure to extreme temperatures. Chlorosis in Nellie Stevens is characterized by a uniform yellowing of leaves and stunted growth. As the disease progresses, leaves start to fall and there is general dieback of the tree. The long-term solution to iron chlorosis includes correcting the soil pH to the desired range of 6.0 to 6.5. A temporary solution is to spray the foliage with an iron compound.
Leaf scorch is a common disease of the Nellie Stevens holly tree and is characterized by the browning of the foliage between the veins and along tips and margins. As the disease progresses, entire leaves wither and brown and there is general dieback of the tree. Scorch is most common after periods of windy, dry weather or heat when the roots are not able to supply water to the foliage at the rate at which it is lost in through transpiration. Trees planted in sandy or gravelly ground and on windy slopes are also more susceptible to leaf scorch. The best preventive measures include keeping the tree in good health with adequate watering and fertilizing.