Council Profile    Committees    Meetings & Reports    Events & field tours    Contact
June 23, 2015
Vol. 2, Issue 5
June 2015
Save the Date!  

July 14 - 16 - CFPC 2015 Golf Tournament (7/14) and Weed Tour (7/15-16); Weed; CEUs are pending.

July 22 - California Forest Pest Council Summer Insect and Disease Field Tour, Klamath National Forest, Happy Camp; Registration is free. DPR credits are pending.

November 4 - 5 - 2015 Annual Meeting of the California Forest Pest Council; USDA Forest Service, Wildland Fire Training & Conference Center; McClellan; More information will be forthcoming.

Plant Pathogens Adapt, Capitalizing on Wet Weather Events

Active localized foliar and needle disease outbreaks currently occurring in northwestern

Red band needle blight, Humboldt Co. By C. Lee, Cal Fire.
California are likely the result of an unusually warm and extended rainy period in December 2014. By late January, extensive foliar and branch symptoms were found on a wide variety of trees from Sonoma through Del Norte Counties.


On planted pines along roadsides (especially Monterey X knobcone pine hybrid widely planted by Cal Trans within the last 50 years), symptoms from red band needle blight (Mycosphaerella pini/ Dothistroma pini) flared up after December rains. Symptoms manifest as widespread needle loss in the lower half of the crown. The pathogen parasitizes pines planted in sites where they are not well adapted to conditions, eventually killing them after many years of repeated outbreaks.


Mycosphaerella arbuticola-killed madrone leaves with new leaves emerging. By C. Lee, Cal Fire.
Foliar death of madrone (caused by Mycosphaerella arbuticola) is another disease syndrome in northwestern California. In moist years that are conducive to airborne fungi spread, many madrones experience death of all the leaves in the canopy. By late winter, the trees look completely dead; however, by early spring, new green leaves start to emerge, pushing away dead leaves. This reflorescence is currently occurring in Humboldt and Del Norte Counties.


Seiridium branch canker on redwood. By C. Lee, Cal Fire.


Damage to redwood branches is prominent this spring, with reddish (flagged) branch tips randomly located throughout the crowns. These branches have been girdled by small cankers that stimulate a flow of resin from the damaged areas. Tiny black fruiting bodies can be seen emerging through the bark near or on the cankers. While these symptoms closely resemble cypress canker, researchers have confirmed the causal pathogen to be Seiridium spp, but have not determined the exact species causing the cankers. Redwood is a previously undescribed host for this fungal genus; therefore, it is unknown whether the damage is transient on affected trees or a long-term problem.


For information about leaf and needle pathogens and their management, see Leaf and Needle Diseases of Trees.

Survival of Fire-Injured Conifers in California

Wildfire intensity and tree injury can vary greatly across a landscape. Conifers die  outright when all foliage in the crown is killed. Trees that sustain lesser injuries to the crown, stem, and roots can survive, but may die prematurely if the injuries are severe. 


Conifer fire. By D. Owen, Cal Fire. 

How well a tree survives is influenced by many factors, such as tree species, age, size, and vigor as well as the extent and location of injury. Most tree mortality takes place within 5 years post-fire, with most dieoff occurring the first 2 years. Fire injuries can also have longer lasting impacts on tree health and may contribute to wood decay or mortality beyond this timeframe.


Insects in the Buprestidae, Cerambycidae, and Siricidae families are principal colonizers of fire-killed or severely fire-injured trees. Some of these insects are attracted by smoke and will lay eggs on trees that are still smoldering. These insects are not considered a direct threat to tree survival because they colonize trees that are dead or dying from fire injury. Conversely, bark beetles (primarily Dendroctonus species) are more likely to colonize trees that are lightly to moderately fire injured and may kill some trees that might otherwise have survived. Bark beetle activity typically increases and may persist   

Charcoal beetle, Melanophila consputa. By D. Owen, Cal Fire. 

for several years in burned areas, but rarely affects healthy trees. 


Fire injury to the crown is the most important variable influencing conifer survival. Another important variable is injury to the inner bark and cambium at the base of the main stem. Bark beetle attacks in response to injury can be an additional predictor of mortality. Guidelines developed by the USFS for gauging tree survival include evaluation protocols that range from basic (estimating crown injury and stem diameter) to more complex (also assessing cambial kill and bark beetle activity). Which variables are measured is best decided based on management goals, experience, and characteristics of the fire damage that occurred. For more information, as well as tables for determining tree mortality probability, see Tree Notes #33, Survival of Fire-Injured Conifers in California.  

Newsletter feedback and ideas are welcome.  Please submit comments to

Summer is here and the camping season is upon us. Remember to always buy or gather firewood from local sources, helping to minimize the spread of pests and diseases - Buy It Where You Burn It


Katie Harrell (formerly Palmieri)
Communications Director  
California Forest Pest Council
California Forest Pest Council | (510) 847-5482 | |

Like us on Facebook Follow us on Twitter