Burning Rules for Cankered Tree Prunings

Once eastern filbert blight gets into a hazelnut tree it can only be removed by pruning off the infected portions. Pruning out cankers before bud break in the spring (early March) also reduces the chance of more infections on healthy trees. Simply cutting down cankers or heavily infected trees is not enough to reduce the threat of EFB. Spores of this fungus can still be produced from cankers sitting in brush piles next to or within orchards. The cankered wood must be destroyed to kill the fungus and reduce your EFB risk. Burning your prunings on site is one way to destroy the infected wood.

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All infected wood should be destroyed before bud break.
Photo by Jay Pscheidt, 1992.

For most of us, we only need to worry about general agricultural burning between October 15 and June 15. Most of our pruning will be done during the winter months and must be destroyed before budbreak in the spring. Fire safety and air quality are the two important factors with regard to burning that are regulated in Oregon. Although it may seem like there are many regulations and that you might get a "run around' when making inquires, in general, there are few restrictions for agricultural burning (as long as it is not grass seed or gain fields).

Before You Burn

Before you burn you need to contact your local fire district about fire safety. In general, you will get a "verbal" burn permit but there may be other regulations depending on your local area. At the very least, they like to know who will be burning and when in case they get any calls about the fire. The following web site has links to many fire districts. They may or may not have information on open burning but remember "agricultural burning" is not subject to local open burn bans.

Oregon Fire Department Links - http://ovfa.org/?page_id=134

Also find out if the day you want to burn is a "burn day". There is a phone number to call or a web site you can look at to get this information. The "grower line" is 503-986-4755 and will let you know about the restrictions for that day. Burn advisories can be obtained at the following web site for various areas of the state. You can even sign up for an e-mail subscription. Remember that you can only burn during daylight hours.

Burn Advisory - http://www.deq.state.or.us/aq/burning/openburning/openburn.asp

If all else fails, give John Byers a call at 503-986-4718. He is the Smoke Management Program Coordinator & Public Information and Outreach Specialist for ODA. He is very helpful and knowledgeable about these regulations.

Alternatives to Burning

Growers are concerned about restrictive regulations for burning EFB infected branches. They would like to chip infected branches but leave the biomass spread throughout the orchard.

We have found that canker pieces with intact stroma do survive the chipping process and produce spores when wetted. Studies were conducted in 2006 and again in 2012-2014 (Heckert et al 2018) to evaluate the risk of this practice.

Spore counts above piles of chipped brush were lower than above intact brush piles with EFB.

In 2006, healthy 2 yr-old Ennis trees were planted into and outside of an area with chipped brush. The incidence of infection did not significantly increase when trees were located within or next to the chipped brush. Similar potted trees were placed within and downwind of chipped brush in both 2012 and 2013. Again, in both years, there was little to no infection of these trees. (In contrast, potted trees were not only infected when placed within intact brush piles but also 60 feet down wind! (Heckert et al 2014)).

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EFB cankers and/or stroma can survive chipping and produce ascospores.
Photo by Jay W. Pscheidt, 2004.

Coarse chipping hazelnut branches with eastern filbert blight EFB cankers appears to reduce the overall risk of disease development. Although viable ascospores can be detected within and above piles of chipped EFB cankers, there are not enough to consistently infect susceptible trees within or downwind of these piles. Growers are advised to grind branches into as small a particle size as possible to break up EFB cankers, encourage decomposition of chips and to limit possible interference with mechanical harvest in the fall. Because whole branches can still pose a threat to disease development, cankered branches need to be ground up prior to bud break in the spring.