Tuesday, August 12, 2008

Greenhouse - Poinsettia Leaf Distortion

Poinsettias will be planted in greenhouses in August throughout Delaware. The following is information on leaf distortion in Poinsettia.

Various types of leaf deformation may occur on poinsettia. Often, the damage begins when the leaves are very small. As plants grow, the mature leaves cover the damaged young leaves, so plants are still marketable.

Branches that develop after pinching may develop a few distorted and misshapen leaves. Environmental stresses, overhead fertilization with phosphorus fertilizers, or abrasion may lead to distorted leaves. Very warm temperatures in August, may contribute to this phenomenon. For growers rooting their own cuttings, changes in temperature and humidity as plants are moved from propagation to finishing houses lead to leaf distortion. It is thought that rapid changes in humidity, result in an accumulation of salts along the leaf margins and veins, resulting in leaf injury. This distortion becomes apparent as the injured leaves grow and expand.

Often, thrips feeding is blamed for distorted leaves. However, with thrips feeding you will see white scarring. Poinsettias are not a favored host of thrips, however, they may migrate from spring bedding plants, garden mums or weeds unto the poinsettias. Fortunately, this feeding damage is often not visible by the time the plants are ready for sale.

Information from the New England Greenhouse Update.

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