Pitch Canker Task Force – Management

More Information

Pitch canker infection is not a sole reason to remove a tree. The decision to remove a tree should be based on more general criteria, such as safety. Thus, if a tree has been deemed hazardous for any reason, it should be removed, regardless of its prospects for recovery from pitch canker.

Any recovery of the tree will be from living material. Infected trees may have numerous dead branches or the top section of the tree may be dead. Dead parts of the tree will not recover and will become increasingly weakened and unpredictable over time. Large dead material should be mitigated as soon as possible. Sometimes the tree may need to be removed even if it shows signs of recovery.

Most pitch canker affected trees will be found in areas where the disease is already present, and the above policy will be applicable. However, where pitch canker occurs in an area that is otherwise free of the disease, more aggressive efforts might be appropriate. To determine if this is applicable to your situation, contact your city forester, county agriculture commissioner, the Department of Forestry and Fire Protection, or your local U.C. Cooperative Extension office. Please keep in mind that county or municipal regulations may require that a permit be obtained prior to tree removal.

Damage caused by pitch canker results first from the death of individual branch tips. Over time, larger branches and even the main stem of the tree can also become infected. At these later stages of disease development, little can be done to influence progress of the disease. However, while symptoms remain restricted to branch tips, it is possible to remove the infected parts through pruning.

The death of branch tips is caused by growth of the pitch canker pathogen, which girdles the branch and cuts off the flow of water and nutrients. Although this results in death of the branch distal to the infection (i.e., between the infection site and the tip of the branch), below this point (i.e. closer to the trunk of the tree), the branch is unaffected. Consequently, if the branch is removed by cutting it below the junction of living and dead needles, the pitch canker infection on that branch can be eliminated. If a tree has a very small number of infected branches, it may be practicable to remove all of them. If so, such a tree can be rendered disease-free, at least temporarily. Unfortunately, in an area where pitch canker is well established (i.e., many trees are infected), it is likely that a tree with symptomatic branches also has infections that are not yet visible. As a result, removal of branches showing symptoms is not likely to rid the tree of all active infections. For this reason, several rounds of pruning may be necessary to remove all infections. Even this may not be sufficient in areas where the disease is well established because new infections can continue to occur. Consequently, there is no guarantee that attempts to rid a tree of pitch canker by pruning out infected branches will prove to be successful.

Notwithstanding the above limitations, removal of infected branches may be worthwhile under some circumstances. In areas where pitch canker is not common, it is possible that inoculum levels are low and new infections will not occur at a high rate. In this case, pruning may actually slow the rate at which the disease develops in a tree. Although new infections are likely to occur, pruning might succeed in extending the useful life of a tree. If aesthetic considerations are of primary importance, such that removal of unsightly branches will allow a tree to be retained in the landscape, then the cost of pruning may be offset by a delay in removal and replacement of the tree.

Guidelines for Handling Woody Material Infested with the Pitch Canker Fungus

Note: The practices described herein are key to the implementation of the Board of Forestry’s Zone of Infestation.

Pitch canker is a fungal disease that infects many species of pine trees and Douglas-fir, but is most likely to be encountered on Monterey, Bishop, or Knobcone pines. First discovered in California in 1986. This disease continues to spread. Preventing spread is important because once pitch canker becomes established in an area there is no way to stop it from infecting and killing trees. No cure or preventative measures exists. Insects spread the disease locally, but people are responsible for long-distance spread. The fungus can survive in cut wood or soil for a year or more. Insects that carry the fungus may survive in cut wood or chips for many months. Chipping does eliminate most insects. Pine firewood, logs, chips, branches, needles, cones, trees and seedlings may all be a source of the pitch canker pathogen.

Cal Fire has authority to impose conditions on the commercial harvest of trees from timberland. For all timber operations regulated by Cal Fire, the Department must be informed if pitch canker is present within the operating area. The State Board of Forestry has declared a Zone of Infestation (ZOI) that largely coincides with the infested counties mentioned above and can be checked on the pitch canker website. Pitch Canker is a “B”-rated disease by the California Department of Food and Agriculture. As a result, the local or destination California County Agricultural Commissioner may restrict the movement of known infected host material. If you are planning to move diseased material from an infested to uninfested area, contact the local and/or destination agricultural commissioners’ offices to determine if there are any restrictions.

Counties with infestations of pitch canker include Alameda, Contra Costa, Los Angeles, Marin, Monterey, Mendocino, Orange, San Benito, San Diego, San Francisco, San Luis Obispo, San Mateo, Santa Barbara, Santa Clara, Santa Cruz, and Sonoma. Infestations may be localized or widespread depending upon the county. Know if you are in an infested area. If you are unsure, assume you are within an infested area whenever working with pine within an infested county. In order to reduce the spread of pitch canker to uninfested areas, The Pitch Canker Task Force recommends the following actions within infested areas:

TREE PRUNING AND CUTTING

• Tools and machinery which are used to prune, cut, or chip trees with pitch canker disease should be cleaned and sterilized before use on uninfected trees or in uninfested areas. Lysol™ or a 10% solution of bleach (1 part household bleach in 9 parts water) are effective sterilants. A logical alternative to repeated cleaning of equipment is to reserve one set of equipment for use only in infested areas and another set for use only in uninfested areas.
• Limbs and small pieces of wood from diseased trees may be chipped and the mulch deposited on site or they may be burned. Any material that is removed from the site should be tightly covered with a tarp during transit and taken to the nearest landfill or designated disposal facility for prompt burial, chipping and composting, or burning. Do not transport diseased wood out of infested counties.
• Logs from diseased trees may be split for firewood for local use, but the wood should be seasoned beneath a tightly sealed, clear plastic tarp to prevent the buildup of destructive insects. California Department of Forestry and Fire Protection TREE NOTE #3, Controlling Bark Beetles in Wood Residue and Firewood, provides specific guidelines for firewood tarping. Do not stack pine firewood next to living pine trees or transport it to uninfested counties.
• Logs that are removed from the site should be taken to a designated disposal facility for prompt burial, chipping and composting, or burning. Do not transport logs from diseased trees out of infested counties unless they are treated according to the log treatment protocol described in Section I of the Guidelines.
• If you are outside of the Zone of Infestation, contact Cal Fire or the County Agricultural Commissioner’s office to report trees you suspect might have pitch canker.
• Make sure that clients and co-workers are aware of these guidelines.

FIREWOOD

• Do not transport pine firewood out of infested counties. If you are traveling from an infested area to camp elsewhere, take another type of firewood with you, such as oak or cedar, or purchase firewood at your destination. For additional information see CA Firewood Taskforce
• If you are camping within an infested county, use up or leave behind any pine firewood you have with you. This should be done even if you brought the firewood with you from an uninfested county.
• Tools and machinery which are used to cut trees with pitch canker disease WILL BECOME CONTAMINATED with the pitch canker fungus. There is little chance of spreading pitch canker if contaminated tools are only used on dead trees or on trees that are not pines. However, if contaminated tools or machinery will be used on living pines, the tools should be cleaned and sterilized before use on uninfected trees or in uninfested areas. Lysol™ or a 10% solution of bleach (1 part industrial bleach in 9 parts water) are effective sterilants. A two minute soak time is recommended when using bleach. A logical alternative to repeated cleaning of equipment is to reserve one set of equipment for use only in infested areas and another set for use only in uninfested areas.

NURSERY STOCK AND CHRISTMAS TREES

Purchasers of Choose and cut Christmas trees

• Individuals are advised not to transport Monterey pine Christmas trees out of infested counties. Purchase and use trees locally; dispose of Monterey pine Christmas trees locally.
• Preferred methods of disposal include:
  • dispose of the tree promptly through a local recycling program, or
  • dispose at a local landfill which either buries or composts green waste, or
  • chip the tree and compost the chips or use them as a mulch around your home.

Sellers of Nursery Stock and Christmas Trees

Christmas tree growers

The best approach to management of pitch canker is to prevent it from becoming established. The pitch canker fungus can be introduced to a Christmas farm as contaminated seed, or as infected seedlings. To avoid such problems, do not use seed that originated within the Zone of Infestation and be sure that seedlings are disease-free. If you do use seed from within the Zone of Infestation, treat the seed prior to use and do not transport it out of the Zone of Infestation. The pathogen can also survive in soil and consequently, it is advisable to remove soil from tools or equipment that have been used in an infested area before moving them to a non-infested area; a high-pressure water wash can be used for this purpose. Additionally, wood-by-products (e.g. shredded fir and pine bark) or compost material used in growing media should be from a source free of pitch canker.

Once pitch canker has become established, it is possible to manage the problem through timely removal of infected trees and treatment of soil. Removal should include the stump and as much of the root system as possible. Disposal of the infected material should be undertaken according to the above guidelines for arborists and tree care workers. Spot fumigation with registered materials can be used to eliminate the fungus from soil at the site of tree removal. Consult with your Country Agricultural Commissioner or U.C. Cooperative Extension office for specific treatment options. On replanting, trees should be closely monitored for development of pitch canker symptoms. If trees become symptomatic they should be removed and the site retreated.

Guidelines for growers of nursery stock

The pitch canker pathogen, Fusarium circinatum, is a “B” rated pest in California. All nursery stock sold in California must be free from “B” rated pests unless sold under a “buyer – seller agreement”. Growers of nursery stock must apply for a “License To Sell Nursery Stock” and are subject to at least annual inspection to assure that State standards for pest cleanliness, labeling and quality are being met. For a “B” rated pest like the pitch canker pathogen, the standard of cleanliness is to be “free from,” meaning that all nursery stock shipments in California must be free from visual symptoms of pitch canker. It is your Agriculture Commissioner’s responsibility to perform visual inspections and determine if the nursery stock meets the “free from” standard of cleanliness, and if it does, to issue California Nursery Stock Certificates for Interstate and Intrastate Shipments (CNSCs).

If you are operating a nursery within the Zone of Infestation, it is recommended that you work with your County Agriculture Commissioner to determine if you have susceptible stock and to acquire and maintain a “free from” pest status for your nursery. Most species of Pinus are susceptible to pitch canker and are considered possible carriers of the pitch canker pathogen. This includes nearly all native California pine species as well as many non-native pine species. Since pitch canker can be soil borne, it is recommended that only bare root stock be shipped outside the Zone of Infestation. Nurseries located within the Zone of Infestation and producing susceptible species of pines should be monitored and tested for Fusarium circinatum at a California Department of Food and Agriculture certified laboratory. Susceptible pines should only be sold if tested and found free of pitch canker, even within the Zone of Infestation. Testing specifications may need to be tailored to each individual case but example protocols are available from your Agricultural Commissioner or Cooperative Extension offices. The Agricultural Commissioner, Cooperative Extension, along with many private foresters and nursery professionals can give you valuable information on ways to raise your nursery stock to minimize the risk of infection. Your nursery may enter into a compliance agreement with your Agricultural Commissioner to help facilitate the movement of “free from” nursery stock of susceptible species.

Sanitation practices in your nursery are critical to ensure a standard of cleanliness that qualifies your stock for CNSCs. Since the pitch canker pathogen is readily transferred, contaminated tools, equipment, etc. can transmit pitch canker to susceptible pines. All tools, equipment, etc. that you use should be routinely sanitized between uses with Lysol or other suitable solution. Each nursery operation needs to be evaluated to determine the most effective means to manage pitch canker. It is necessary to work with your Agricultural Commissioner and Cooperative Extension personnel to control this destructive tree disease.

Shipments with CNSCs need not be held for inspection in California, but are subject to review by the Agricultural Commissioner of the receiving county. The destination Agricultural Commissioner may verify the shipment meets the State standards for nursery stock cleanliness. If pitch canker is found in your shipment, the destination Agricultural Commissioner may, at your expense, destroy the infected part of the shipment, return it to your nursery, or have you make other arrangements, or may approve a “Buyer/Seller Agreement.”

Note. The Pitch Canker Task Force recommends that in addition to meeting the California standards for “free from” that Monterey pine growing stock be lab tested to determine whether the pitch canker pathogen is present. We believe that visible inspection is not adequate to determine “free from” status. We encourage nurserymen to enter into voluntary compliance agreements in the county of origin. Seedling buyers need to be aware that there is a significantly increased risk of pitch canker pathogen spread if they purchase stock that has not been lab tested for the pathogen.

SEEDS

• Seeds collected in pitch canker infested areas may carry the pathogen, even if they are taken from cones on apparently healthy trees. Pine seeds should not be transported out of pitch canker infested areas.

CHIPS

• Unless the chips have been composted, do not transport pine chips out of infested counties. Composting chips prior to transport should greatly reduce or eliminate the potential for disease spread.
• Within infested areas, the use of infected chips for mulch would contribute little to the total number of sources of the disease. However, it is best to use chips near the site of origin as it will minimize dispersal of the pathogen to uninfested areas within an infested county. Avoid using potentially infested chips near healthy pines or Douglas-fir.
• Chipping infected wood will reduce but not eliminate insects that carry the pitch canker pathogen. Chipping has little impact on pathogen survival and may serve to more thoroughly distribute the pathogen among the chips through contamination.
• Material that is composted under a treatment regime that eliminates the pitch canker pathogen (see guidelines below) may be transported out of infested counties.
• For chips that are not composted or otherwise treated to eliminate the pathogen, the following will greatly reduce the possibility of pathogen spread when said material is transported out of infested counties:
  • the transportation route is free of indigenous or planted pines
  • the material is shipped in tightly enclosed trucks
  • no indigenous or planted pine forests are within a ten mile radius of the destination area.

COMPOSTING

• Composting can be an effective means of eliminating the pitch canker pathogen from infected branches. The composting operation should be conducted as close as possible to the source of the infected material.
• Wood to be composted should be chipped and mixed with a source of nitrogen such as grass clippings or manure. Elimination of the pathogen requires exposure to 50 C (120 F) or higher for at least 10 days. As it will be necessary to turn the pile to ensure exposure of all material to the higher temperatures at the interior, the duration of the composting will necessarily be longer than 10 days. Standard commercial composting operations will ordinarily exceed the minimum time and temperature required to kill the pathogen, but if this is in doubt, temperatures should be monitored to confirm they are high enough. Note that moist conditions in a compost pile facilitate the elimination of the fungus. If dry heat is used, as by simply placing logs under plastic, higher temperatures may be required to kill the fungus.

LOGS and LUMBER

• The preferred management option for untreated pine logs is that they be milled within the Coastal Pitch Canker Zone of Infestation (see addendum).
• Do not transport pine logs with intact bark out of infested counties, unless you are positive the logs originated from an uninfested area. Removing all bark prior to transport should greatly reduce the potential for disease spread, as would prompt milling of the logs.
• Pine bark should not be transported out of infested counties. Handling, disposal and use is the same as for other pine green waste.
• Pine logs originated from an uninfested area (defined as a minimum of 10 miles from the nearest known infected tree) and the source trees are inspected to confirm they are disease-free, the logs pose little or no threat of spreading the pathogen out of the Zone of Infestation.
• Pine logs from infested areas pose little or no threat of spreading the pathogen out of the Zone of Infestation if the logs have received one of the following treatments:
  • have been stockpiled for one year or more within the Zone of Infestation.
  • heated to 160¬∫F at the center of the log for 75 minutes
  • have been completely debarked and all bole cankers removed
• When logs from within the Zone of Infestation are processed outside of the Zone, wood residue from those logs should not be stored, utilized, or disposed of in a manner that brings it in close proximity to living pines. Consider burying, burning, or composting the material. If it is used as a soil amendment or mulch, keep it away from living pines.
• Kiln-dried lumber (dried until the center of the largest dimensional piece reaches 140¬∫F) can be shipped out of the Zone of infestation immediately after treatment.
• Air-dried lumber, provided it is free of deep-wood insects, does not present a hazard for pitch canker spread. Lumber which comes from trees that were dead or dying prior to their harvest could harbor deep-wood insects, and thus should be used within the Zone of Infestation or cured a minimum of one year prior to being moved out of the Zone.

IMPORTED PINE MATERIAL

• Pitch canker occurs naturally in the southeastern United States and Mexico and has been introduced to some other countries. It is not known how pitch canker came to California, but the closest possible sources are the Southeast and Mexico. In the southeastern US, pitch canker is distributed from Virginia to Florida and west to eastern Texas. The complete distribution in Mexico is unknown, but it occurs in at least 14 states, from the Texas border into central Mexico.
• Pine material from these areas could potentially be contaminated with or infected by the pitch canker pathogen. For example, it was recently discovered that bales of pine needles imported into California from Georgia were contaminated with the pathogen.
• Only import pine material from these areas if it is known to be free of pitch canker. If infected or contaminated material is imported, it should be treated to eliminate the pathogen or only used in settings far removed from living pines.

OTHER

• Any untreated pine material that originates within infested counties is a potential source of pitch canker disease, unless the material has been treated to eliminate the disease or has been certified to be disease-free.

REGISTERED PROFESSIONAL FORESTERS AND LICENSED TIMBER OPERATOR

• On June 4, 1997 the State Board of Forestry passed a resolution establishing the Coastal Pitch Canker Zone of Infestation. The Zone encompasses all or parts of 21 counties on or near the coast from Mendocino County to San Diego County. Infested counties are listed at the beginning of this document.
• Map of the Zone of Infestation. The Zone includes all infested areas as well as adjacent areas that might reasonably be expected to become infested in the near future. The distribution of the disease is discontinuous and thus there are infested as well as uninfested areas within the Zone.
• Know when you are working within an infested area. The Department of Forestry and Fire Protection (Cal Fire) has the authority to impose conditions on the commercial harvest of trees from timberland within the Zone of Infestation. Such actions are be carried-out on a case by case basis and depend upon the harvest operation’s potential to contribute to disease spread. For all timber operations regulated by the Department, the Department must be informed if pitch canker is present within the operating area.
• Do not transport infected or contaminated material to areas that are free of the disease.
• When cutting or pruning a diseased tree, clean tools with a disinfectant before using them in uninfested areas. Lysol™ or a 10% solution of bleach (1 part household bleach in 9 parts water) are effective sterilants. A two minute soak time is recommended when using bleach.
• If you are outside of the Zone of Infestation, contact Cal Fire or the County Agricultural Commissioner’s office to report trees you suspect might have pitch canker.
• Make sure that clients and co-workers are aware of these guidelines.
• The initial draft of this position paper was developed by the Pitch Canker Task Force and approved on January 23, 1997. It was amended and reapproved on September 7, 2000 and reflects conditions current as of that date.

BACKGROUND

Pitch canker is a fungal disease that infects many species of pine trees. It infects Monterey pine Christmas trees and has been found in ornamental Douglas-fir at one location in Santa Cruz County. First discovered in California in 1986, its range is spreading and now includes 16 coastal and adjacent inland counties from Mendocino to San Diego. There is no cure and thousands of Monterey and Bishop pine trees have been killed.

Bark beetles, which carry the fungus, primarily infest Monterey and Bishop pines but also feed and breed on inland forest trees such as ponderosa pine. As yet, the disease has not been found in the Sierra Nevada or other heavily forested parts of the state.

Transport, disposal and use of diseased material should be done so as not to spread the disease to uninfested areas. Insects spread the disease locally, but people are responsible for long-distance spread. Pine firewood, logs, chips, branches, needles, cones, and trees may all be a source of the disease.

University of California scientists are currently doing studies to characterize the survival of the pitch canker fungus, Fusarium subglutinans f.sp. pini and associated insects in pine green waste, but the full results are not yet in. The fungus can survive in cut wood up to a year. The fungus also survives in soil up to 8 weeks or more. Insects may survive in cut wood or chips for many months. Chipping does not eliminate insects. When branch tips infested with twig beetles are chipped, some insects may emerge up to 12 weeks after chipping. Undoubtedly, some insects will survive even longer in chipped material. All of these findings implicate pine green waste as a viable source for the spread of pitch canker disease.

Reforestation Recommendations

12/18/00

Recommendations for reforestation in areas affected by pitch canker Landowners are frequently faced with the question of how to replace Monterey pines in areas where pitch canker is a problem. In close proximity to native stands of Monterey pine, several issues should be considered before a decision on replanting is made. First, replanting with Monterey pine may be desirable in order to maintain the character of the community and, where large tracts of land are involved, to help preserve the genetic and aesthetic resource that this species represents. Second, not just any Monterey pine will do. There are three native populations of Monterey pine in California, at Ano Nuevo, Monterey and Cambria, each of which is genetically unique. Consequently, it would be a mistake to import genetic stock from outside the native population where the replanting is to occur, as it could degrade the genetic integrity of the local population. For this same reason, trees originating from breeding programs (i.e. selected for rapid growth and other commercially valuable attributes) should also be avoided. Third, although the nature and extent of variation within each Monterey pine population is not fully understood, one should assume that trees from distinct areas or habitats may be specifically adapted to the site where they occur. Thus material selected for replanting should be as local in origin as possible. Finally, in the absence of any prior selection for resistance to pitch canker, replanted Monterey pines have a high probability of sustaining infections and possibly dying from this disease. However, in all three native populations some percentage of trees will show resistance to pitch canker and the options detailed below offer some alternative means to take advantage of this. Additional background information is provided below under the heading “What is genetic resistance?”

Option 1

The preferred strategy for reestablishing Monterey pine would be to allow natural regeneration to occur. This is more likely to be practical in relatively large areas (> 0.1 acre). If local conditions, such as a dense understory preclude development of a seedling stand, various measures may be undertaken to improve the site so as to encourage regeneration. Contact your local forester or the California Department of Forestry for additional information on this. Where natural regeneration does occur, it can be expected that pitch canker will eventually infect some or all of the young trees. However, the trees will vary in their susceptibility and some may sustain little or no damage. Although this approach offers no guarantee that the frequency of resistance to pitch canker will be sufficient to provide the desired density of mature trees, it represents the least intrusive approach to reforestation.

Option 2

If option one is acceptable in principle but there is insufficient seed to produce a stand, locally collected seed could be introduced. Whereas it would be desirable to use seed from known resistant trees, no such seed source is presently available. An alternative would be to collect seed from symptomless trees, some of which may be resistant. Even if the parent tree is resistant, the seed is likely to produce a significant number of susceptible individuals. However, a small percentage of resistant individuals may be sufficient to establish a stand. Although the planting site itself may not be in a native forest, if it is close to such a forest, the trees may eventually contribute pollen to the nearby native population. For this reason, seed for replanting should be obtained from native trees, as close as possible to the planting site. If the area to be planted is large, an attempt should be made to diversify the source of seed, by collecting cones from: 1) multiple trees, separated from each other by 100 meters if possible, 2) trees of different ages, and, 3) different heights in the same tree. Avoid collecting from any trees that appear to have been planted as they may be non-local in origin. Also try to avoid trees that are obviously infected by either western gall rust or dwarf mistletoe.

Option 3

An alternative to establishment from seed is to transplant known resistant seedlings from a reputable source. This should be viewed as a last resort to maintain the presence of Monterey pine. Local and regional efforts are underway to develop resistant planting stock for all the native populations, and these may be available in the near future. Contact your local forester or the California Department of Forestry for more current information.

What is genetic resistance?

In most areas where pitch canker is well established, it is possible to find Monterey pine trees with few or no symptoms of the disease. In some cases, these trees have simply not been exposed to the pathogen in sufficient quantities or under the right circumstances for an infection to become established. Eventually they will become diseased. However, some trees will not develop symptoms of pitch canker even when they are challenged with large quantities of inoculum under conditions that are conducive to infection. These are the trees we consider to be “genetically resistant” to pitch canker. As this term implies, resistance is determined by the genetic make up of the tree. That is, specific genes are involved in determining whether or not an individual Monterey pine is susceptible to pitch canker.

Genetic resistance has proven to be highly effective in the control of many plant diseases. However, there is never a guarantee that it will provide complete disease control in perpetuity. Over time, pathogens can adapt to resistant plants, rendering them more susceptible to disease. This can result from genetic mutations in the resident population of the pathogen or from the introduction of new strains. Where resistance in the plant host is determined by only one gene, a single gene mutation in the pathogen could allow it to overcome host resistance completely. On the other hand, where resistance is determined by many genes, a single gene change in the pathogen is less likely to have a major effect on the susceptibility of the host. Thus the number of genes that contribute to genetic resistance in the host has a direct effect on the pathogen’s ability to overcome this resistance.

The genetic basis for resistance to pitch canker in Monterey pine is not yet known with certainty but the available evidence indicates that many genes are probably involved (= multigenic resistance). One characteristic of multigenic resistance is a wide range of variation in susceptibility. It is analogous to a trait such as height in humans. Some people are short, others tall, and most are somewhere in between. This reflects the fact that height is a characteristic influenced by many genes. So it appears to be with susceptibility to pitch canker in Monterey pine. Some trees are highly susceptible and will become heavily infected, others will sustain no infections, and many others will fall between these extremes. Based on such observations, it seems likely that resistance to pitch canker is determined by many genes.

Multigenic resistance tends to be much more durable than single gene resistance and offers reason for optimism that resistance in Monterey pine can provide lasting protection against pitch canker. Changes in the pathogen population will surely occur but it is unlikely that they will dramatically alter the resistance of most trees. Over the long term, the host population can change as well, maintaining a balance that will limit the disease causing ability of the pathogen. This same process occurs naturally and has allowed Monterey pine to adapt to the many insect and disease problems that are of long residence in native forests.

Given the problems with pitch canker, why plant Monterey pines at all? In most urban environments, one may opt to avoid any risk of damage from pitch canker by utilizing non-susceptible species as landscape trees. But in a native Monterey pine forest and at the urbanized border of such a forest, planting exotic species will degrade the integrity of a limited natural resource. If Monterey pines that are lost to pitch canker are replaced with non-native tree species, the loss to the native forest will be made permanent. As an alternative, killed trees can be replaced with Monterey pines that are genetically resistant to pitch canker, thereby helping to sustain this species in its native habitat.

Where do I go to get resistant trees?

Presently there is no commercial source of resistant seed or seedlings. Several programs are in place to develop this material, which may be available in the near future. If you are interested in replanting with Monterey pine you should contact local or state agencies to determine what your best options are. A good place to start would be your city forester or U.C. Cooperative extension office.

Long distance spread of the disease occurs when materials infected with the pitch canker fungus are transported to uninfested areas. Preventing disease spread is important because once pitch canker becomes established in an area there is no way to stop it from infecting and killing trees. No cure or preventative exists. While one goal for the Zone is to slow disease spread, neither the Board nor the Department of Forestry and Fire Protection (Cal Fire) has the authority to impose and enforce a quarantine on the movement of infected material. The Department does have the authority to impose conditions on the commercial harvest of trees from timberland within the Zone of Infestation. Such actions would be carried out on a case-by-case basis and depend upon the harvest operation’s potential to contribute to disease spread. For all timber operations regulated by the Department, the Department must be informed if pitch canker is present within the operating area.

Pitch canker is a “B”-rated disease by the California Department of Food and Agriculture. As a result, the local or destination California County Agricultural Commissioner may restrict the movement of known infected host material. If you are planning to move diseased material from an infested to uninfested area, contact the local and/or destination agricultural commissioner offices to determine if there are any restrictions.

Slowing disease spread can only be achieved through a cooperative effort among affected governments, businesses, organizations, and individuals. It is the intent of the Department to work with all affected entities to achieve the goals of slowing disease spread and reducing disease impact. Department staff are available to provide training and assistance related to these goals.

Forestry professionals throughout the state can help slow the spread of pitch canker by learning to recognize symptoms of the disease and taking appropriate action when the disease is encountered. The pitch canker fungus can be transported on pruning tools, firewood, logs, Christmas trees, seedlings, wood and bark chips, cones, seeds, and wood waste. The disease has heavily impacted Monterey and bishop pines, but we also know that most pine species and even Douglas-fir are susceptible. Here are some things you can do:

• Know when you are in an infested area.
• Do not transport infected or contaminated material to areas that are free of the disease.
• When cutting or pruning a diseased tree, clean tools with a disinfectant before using them on uninfected trees.
• If you are outside of the Zone of Infestation, contact Cal Fire or the County Agricultural Commissioner’s office to report trees you suspect might have pitch canker.
• Make sure that clients and co-workers are aware of these guidelines.

Reprinted from Licensing News, Vol. 16 No. 2, October 1997. Board of Forestry, Professional Foresters Registration Program. p. 4-6

Other Related Information

• Diplodia Blight
• Western Gall Rust
• Dwarf Mistletoe
• Sequoia Pitch Moth IPM | Sequoia Pitch Moth Tree Note
• Ips Beetle
• Red Turpentine Beetle