* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Leaf Galls of Azaleas and Camellias
Survey
Document related concepts
Ornamental bulbous plant wikipedia , lookup
Plant nutrition wikipedia , lookup
Plant defense against herbivory wikipedia , lookup
Plant reproduction wikipedia , lookup
Plant physiology wikipedia , lookup
Plant use of endophytic fungi in defense wikipedia , lookup
Plant morphology wikipedia , lookup
Evolutionary history of plants wikipedia , lookup
Plant stress measurement wikipedia , lookup
Venus flytrap wikipedia , lookup
Glossary of plant morphology wikipedia , lookup
Plant evolutionary developmental biology wikipedia , lookup
Transcript
Leaf Galls of Azaleas and Camellias Exobasidium vaccinii (Fuckel) Woronin and Exobasidium camelliae Shirai Leaf galls on azaleas and camellias are relatively common in Louisiana, especially in years with extended periods of cool, wet weather during the spring. Although these diseases most commonly occur on leaves, they also can occasionally be found affecting stems, flowers and seed pods. On azaleas, leaf galls are caused by the fungus Exobasidium vaccinii, which also will cause leaf galls on a variety of other members of the family Ericaceae. On camellias, leaf galls are caused by E. camelliae, and sasanquas are particularly prone to this disease. The growth deformities these diseases cause are unsightly and sometimes grotesque, but they are not particularly serious, except on very susceptible cultivars. In fact, the fleshy galls on azaleas often are referred to as “pinkster apples” and are edible! Leaf gall symptoms appear soon after flowering and are quite apparent as the leaves (or portions of a leaf) become thickened with a fleshy or leather-like texture and their shape is distorted. At first, these galls tend to be pale green, pink or white, but they eventually become white and powdery as the fungus develops on the leaf surface and begins to produce spores, which make up the white powdery substance coating the galls. These spores are readily dispersed in air currents and by splashing water, and subsequent infection occurs only on young, tender growth. Later, as the leaves shrivel up, they dry out, turn brown and become quite hard. These galled leaves may then fall to the ground where, if left, they can serve as a source of next spring’s inoculum. The fungus also is thought to survive within asymptomatic infected tissues and as spores within bud scales. In the landscape, this disease is managed primarily by the use of cultural practices. These include practices that increase airflow and promote rapid drying of the foliage as well as sanitation practices Figure 1. Azalea leaf galls Figure 2. Close-up of azalea leaf gall that reduce the production and availability of additional inoculum. When establishing new plantings, it is important to maintain adequate plant spacing so you don’t create an environment conducive to disease development. Also, avoid planting in protected areas without adequate air movement, such as enclosed courtyards, etc. For established plantings, selective thinning of the canopy to increase airflow is recommended. Frequent inspection of the plants and removal of infected leaves when they first appear are often all that is needed to control this disease. If large numbers of leaves are affected, prune the plants during late spring or early summer to remove infected leaves and stimulate new growth. Also, be sure to rake up and destroy affected leaves that have fallen to the ground under the plants. Fungicides, such as triadimefon and others used to control petal and flower blights, may also give some control of leaf gall when they are applied beginning at bud break and repeated every 10 days as long as environmental conditions are suitable for disease development. Figure 3. Leaf galls on Camellia sasanqua Visit our website: www.lsuagcenter.com Author Donald M. Ferrin, PhD Department of Plant Pathology and Crop Physiology Photo Credits Charles Overstreet (Figure 1 and 2 ) Gerald Roberts (Figure 3) Louisiana State University Agricultural Center, William B. Richardson, Chancellor Louisiana Agricultural Experiment Station, David J. Boethel,Vice Chancellor and Director Louisiana Cooperative Extension Service, Paul D. Coreil,Vice Chancellor and Director Pub. 3180 (online only) 12/10 The LSU AgCenter is a statewide campus of the LSU System and provides equal opportunities in programs and employment.