Citrus Gummosis Why do citrus trees have, in general, an unhealthy appearance? Some citrus trees look unhealthy because of a common fungal disease called gummosis. Such trees are sparsely foliated with much twig dieback. Trees become infected when fungal spores on the ground splash onto the trunk. If the trunk remains wet for many hours, whether from rain droplets or irrigation, infection takes place.
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Symptoms of damage of brown rot caused by Phytophthora citrophthora on a citrus tree. Brown rot caused by Phytophthora citrophthora on a citrus fruit. Scientific Name Biology Description Phytophthora spp. Both P. They complete their life cycles in the soil Damage Foot rot or gummosis is caused by two Phytophthora spp.. Symptom development often begins near the soil line; dark water-soaked areas are formed in the bark and a sour smell may occur in wet conditions.
Water-soluble gum exudes from affected tissues and is particularly noticeable in dry weather. Longitudinal cracking of bark, accompanied by profuse gumming, usually is positive evidence of infection.
Soil removal around affected trees reveals bark that is water soaked, slimy, reddish-brown, or black in late stages. Brown necrotic areas can be seen extending to the cambium and wood.
Advanced stages of infection will result in yellow, sparse foliage. At later stages, the dead bark dries, shrinks and cracks and patches may fall off, leaving an open canker.
Trees may later collapse and die due to the girdling action of the fungal infection. Infected fruits develop a soft brown rot eventually with a characteristic pungent odor. It attacks aerial parts of the trunk and major limbs. Lifecycle Under suitable environmental conditions, chlamydospores germinate and produce vegetative hyphae or sporangia which initiate asexual reproduction.
Sporangia are also formed by mycelial hyphae in the presence of water flooding , which is essential for this process. Both pathogens produce papillate sporangia. Sporangia of P. In water, sporangia are usually borne singly or in very loose sympodia of sporangia. Zoospores are produced inside these sporangia, and are liberated via the sporangial papilla which dissolves.
The reniform zoospores are highly motile. They then round up and encyst, casting off their flagellae. After attachment they germinate and infect cortical root tissue. Oospores are produced only by P. The frequency with which oospores are formed under field conditions and their role in survival and disease transmission is unknown.
Phytophthora foot rot, root rot, brown rot, gummosis, and Phytophthera-Diaprepes PD complex Disease cycle Phytophthora is a water mold Class Oomycetes, formerly a fungus-like protist that is found throughout the world. Under favorable conditions high moisture and temperature it produces large numbers of motile zoospores that can swim in water for short distances. These zoospores are the infective agents that may be transported in rain or irrigation to the roots. When zoospores contact roots they encyst, germinate and enter the root tip resulting in rot of the entire rootlet. Foot rot or gummosis occur when zoospores splash onto a wound or bark crack around the base of the trunk. Additionally, there is an association of Phytophthora root rot when roots are damaged by citrus root weevils, particularly Diaprepes abbreviatus.
Symptoms of damage of brown rot caused by Phytophthora citrophthora on a citrus tree. Brown rot caused by Phytophthora citrophthora on a citrus fruit. Scientific Name Biology Description Phytophthora spp. Both P. They complete their life cycles in the soil Damage Foot rot or gummosis is caused by two Phytophthora spp..
What Causes Citrus Foot Rot: Controlling Citrus Gummosis In Gardens
What is gummosis? What is Gummosis? Gummosis is a nonspecific condition where sap leaks from a wound in the tree. It usually occurs when the tree has a perennial or bacterial canker, or is attacked by the peach tree borer. However, gummosis can also be caused by any wound to a stone fruit tree, including winter damage, disease damage, or damage from a gardening tool. If you see gummy sap leaking out of your peach , plum , cherry or apricot tree , it is probably gummosis.
How to Treat Gummosis, or Bleeding in Tree Bark
Forestry Expert B. He is a member of the Society of American Foresters. Gum or sap draining from a tree trunk or limbs is common in trees in the genus Prunus, which includes peaches and cherries, but it can happen in many species. This sap flow can be caused by biotic diseases , which are triggered by living organisms such as fungi, and abiotic injury, caused by non-living factors such as sunlight and temperature change.