Charles H. Bronson, Commissioner    -    James R. Karels, Director
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CONIFER STEM Diseases:
Pitch Canker
Fusiform Rust
Eastern Gall Rust
Red Heart of Pine


 
Forest Health > Insects and Diseases publication

Diseases of... Conifer Stem

Common Name:

 

Figure 13- Simplified life cycle of the pitch canker fungus on slash pines in Florida.

PITCH CANKER

Pitch canker.

 

 

Resin oozing from slash pine stem infected with the pitch canker fungus.

 

 

 

 
Pathogens: Fungus Fusarium moniliforme var. subglutinans
Common Hosts: Slash Pine Pinus elliottii
Other Pines Pinus spp.
Significance:
 Pitch canker affects most native species of pines in Florida, but it is most common on slash pine. Severe outbreaks of pitch canker are known to occur periodically and can result in significant stem and crown damage as well as mortality to slash pines in commercial forest plantations and urban environments. Trees of all ages are susceptible to pitch canker, but infections are most common in trees 10 years of age or older. Infected seedlings in forest tree nurseries are usually killed by the disease. To date, outbreaks of pitch canker in nursery seedling crops have not reached economically important levels. Pitch canker is usually of little consequence on species other than slash pine, although considerable damage to loblolly pine in seed orchards is not uncommon. In addition to damaging trees per se, the pitch canker fungus is also capable of infecting and damaging pine cones and seed.
Recognition:

Pitch canker is usually first recognized by the appearance of definitive reddening or "flagging" of infected terminal or lateral shoots. These dying shoots appear most frequently from late fall through the following spring. Close examination of infected shoots typically reveals the presence of abundant pitch (resin) exuding from slightly depressed cankers (areas of restricted diameter growth due to death of the cambium) at the point of infection. Depressed cankers are frequently not present on small diameter shoots. Wood beneath cankers is characteristically soaked with pitch. Infected shoots usually die within a matter of months. Old infections are readily identified by the dull gray-brown appearance of the dead shoots and needles. Needles frequently adhere for long periods of time to pitch canker-killed shoots because they are matted and stuck in the exuded pitch. The most characteristic symptom of pitch canker infection is nursery seedlings is an internal pitch-soaking of the seedling stem at or near the soil line. Small clumps of resin-soaked soil often adhere to infected stems near the point of infection.

Infection Biology:

 Pitch canker infections are initiated by microscopic spores called conidia (sing., conidium). The fungus enters susceptible tissues through natural, man?made, or insect?created wounds and normally does not penetrate intact tissues. Infections may occur throughout the year but are most commonly occur during the late summer and fall. At that time of year in Florida, violent thunderstorms are common and spore dispersal is greatly enhanced by the action of the accompanying wind and rain. It is also during that time of year that the deodar weevil feeds on the susceptible green shoots of slash pine. The deodar weevil is known to carry (vector) the pitch canker fungus and introduce the pathogen into its feeding wounds. Following disease development, small (less than 3 mm), salmon-orange, wart?like fruiting bodies (sporodochia; sing., sporodochium) are produced on dead or dying branches, most typically in needle fasicle scars. These fruiting bodies produce large masses of conidia, and the cycle is completed. The pitch canker fungus is apparently introduced into forest tree nurseries on infected or contaminated seeds, although introduction via airborne spores is probable as well.
Control:

Simple, effective controls for pitch canker are unknown. Planting pines on suitable sites and in suitable geographic locations is recommended. Avoid unnecessary wounds to susceptible pine species. Reduce local fungus inoculum (spores) by removing and destroying diseased trees and/or branch material. Minimize the potential for introduction of the pathogen into forest tree nurseries by maintaining clean (disease?free) seed orchards and seed production areas. This practice will reduce potential for infected or contaminated seed.

Typical "flagging" of slash pine branches and terminals infected with the pitch canker fungus.

 

 

Typical "flagging" of slash pine branches and terminals infected with the pitch canker fungus.



Bulletin No. 196-A | Printed October, 1983 | Contact the Forest Health Section
Division of Forestry Shield


Florida Department of Agriculture and Consumer Services