September 7, 2026

Orchard and Vineyard Prunings: Burning vs. Chipping

In parts of California, burning orchard prunings isn't a choice anymore. Here's where prunings still qualify for a burn permit, what chipping actually costs per acre, and what nine years of UC Davis data says about the yield tradeoff.

For most of the last century, the answer to "what do I do with the brush?" was a windrow and a match. It was cheap, it was fast, and it fit between harvest and the next pass with the disc.

In a growing number of places, that answer is no longer available — not because the fire got more dangerous, but because the smoke did. And the odd thing about the shift is that the research came out mostly in the grower's favor. The alternative that regulators pushed people toward turns out, in the longest trials we have, to be the one that produced more nuts per acre.

Quick answer:

Where you farm decides whether this is even a choice. In California's San Joaquin Valley, surface harvested prunings and orchard and vineyard removals have been prohibited from open burning since January 1, 2025. In Washington, annual orchard prunings don't require an air quality burn permit at all.
"Prunings" and "removals" are different regulatory animals. Annual prunings, whole-tree tear-out, and attrition (dead limbs, stumps, suckers) are treated as three separate categories in most rule sets, and the one you're holding determines the paperwork.
Chipping costs more up front and less over time. UC Davis's rough comparison puts grinding at several hundred dollars an acre above the burn baseline; a nine-year almond trial found 20% higher kernel yields and 20% better water use efficiency in the recycled block.
The first year is the hard one. Incorporated chips immobilize nitrogen. UC research suggests roughly 50–70 lbs N per acre in year one, after which the trees catch up.
Disease is the standing exception. Nearly every program that has phased out routine pruning burns still keeps a door open for material a plant pathologist says has to be destroyed.

Prunings, removals, and attrition are not the same thing

Growers tend to use "brush" for everything woody that comes out of a block. Air districts don't, and the distinction is where most permit confusion starts.

The San Joaquin Valley Air Pollution Control District splits the category three ways, and the phase-out hit each part on a different schedule. Most field crops, prunings, large orchard removals, and weed abatement were prohibited from open burning by 2010. The final step landed on January 1, 2025, when small orchard removals, vineyard removals, and surface harvested prunings were also prohibited.

What survived is narrow. As of that date the District may only issue agricultural burn permits for a short list that includes prunings and orchard removals from apple, pear, and quince only, rice straw and rice field levees, ponding and levee banks, ditchbanks and canals, tumbleweeds, noxious weeds, diseased material where the county agricultural commissioner determines burning is the only available disposal method, fertilizer and pesticide paper sacks, diseased beehives — and attrition.

That last one is worth reading twice. Attrition covers suckers, dead or broken branches, stumps, trunks, and dead trees from an orchard or vineyard. It explicitly does not include annual prunings or material from an orchard or vineyard removal. A grower who assumes "attrition" is a catch-all for orchard wood is going to have an uncomfortable conversation with an inspector.

Even the material that still qualifies is gated daily. A permit gets you eligibility; the District's Smoke Management System decides whether today is a burn day — the same two-layer structure we cover in agricultural burn notifications.

Washington: prunings are exempt, tear-out is not

Head north and the logic nearly inverts, which is a good reminder that the crop doesn't set the rules — the regulatory model does, the theme running through our state-by-state permit guide.

Washington's Department of Ecology publishes a plain two-column table. No agricultural burn permit is needed for fence rows, ditch banks, irrigation canals, annual orchard prunings, or windblown tumbleweeds. A permit is needed for post-harvest field and crop residue, cereal grain stubble, bales, spot burns, orchard and field flaming, and vineyard and orchard tree tear-outs. Pile permits — the category that covers orchard tear-out — run $80 for the first 80 tons plus $1 per additional ton.

Exempt from the air permit is not exempt from everything. Washington still requires growers to contact the local fire department, check for a local ban, and call the daily burn decision line before igniting. As of this writing a governor's emergency proclamation has banned burning statewide through September 30, 2026 — a live example of the point we make in burn bans vs. burn permits: an emergency ban overrides a valid permit, and an exemption from permitting is not an exemption from a ban.

The state's Orchard Crops Best Management Practices guidance, written by the Agricultural Burning Practices and Research Task Force, goes further than the permit table. It notes directly that even though pruning burns don't require a permit, "the Task Force strongly recommends that whenever practical the grower mulch up the prunings rather than burning them." For tear-out that does need a permit, growers have to show burning is reasonably necessary and that no practical alternative is reasonably available — and the document defines a non-burning alternative as reasonably available when it is "successfully and customarily being used locally by others in circumstances similar to the grower's situation." Your neighbor buying a chipper can, over time, change what you're allowed to do.

That guidance also carries an anti-backsliding provision and caps transition plans — situations where an alternative exists but the grower isn't using it yet — at three years.

What chipping actually costs

The honest version: more, up front, and it varies enormously with screen size and chip volume.

UC Davis's cost-benefit guide for almond orchard removal compares three scenarios against burning as the baseline. Pulling trees, deep ripping, discing, land leveling, and berms are common to all three. The difference is what happens in between: burning with a permit ran $400–$500 per acre, while grinding ran $500–$700 per acre, with spreading chips adding $125–$400 on top if you're recycling rather than hauling. Net, the guide puts grind-and-haul at roughly $0–$200 per acre above the burn baseline and grind-and-recycle at $125–$810 above it.

Two caveats matter. Those figures are explicitly labeled a rough guide, built on 2016 UCCE cost-of-cultivation studies and 2019 interviews with removal companies — treat them as relative magnitudes, not quotes. And screen size drives grinding cost more than most growers expect: a horizontal grinder with a 4-inch screen processes roughly an acre an hour, but dropping to a 2-inch screen for faster chip breakdown cuts that to 0.5–0.75 acres per hour and adds $100–$200 per acre.

The gap narrows when incentives enter. The Valley Air District's Ag Burn Alternatives Grant Program reimburses commercial ag operations for chipping orchard and vineyard removal material and using it for soil incorporation, on-site land application, or off-site beneficial re-use such as mulch, compost, or roadside dust suppression. Funding is first-come, first-served, capped at 100 acres per entity per calendar year, and requires pre- and post-inspection plus certification that the ground stays in agricultural use. A separate fleet-expansion track funds up to 65% of new Tier 4 chipping and grinding equipment for contractors — which is the mechanism quietly making custom chipping available in places it wasn't a decade ago.

The nine-year yield answer

This is the part that changes the calculation from compliance cost to investment.

Whole orchard recycling — grinding whole trees on site at removal and incorporating the biomass into the topsoil before replanting — got serious research attention in California partly because the old escape valves closed at once: burn permits got harder and more expensive, and since 2015 a large number of the state's biomass power plants shut down. Growers needed somewhere to put the wood.

At UC's Kearney Agricultural Research and Extension Center in Parlier, a block recycled in 2008 and replanted in 2009 was tracked against a conventional push-and-burn control. The published results show recycled plots out-yielding the burned control in every year from 2011 through 2017 — 13,433 lbs/acre cumulative versus 11,930, a difference of about 1,503 lbs/acre. In 2017 the trial found a statistically significant 20% increase in kernel yield and water use efficiency under regular (100% ET) irrigation.

The catch arrives in year one. Incorporating 40–60 tons of chips per acre puts 15–30 tons of organic carbon into the soil, and the resulting carbon-to-nitrogen ratio immobilizes nitrogen — visible as stunted shoot growth on first-year trees. UC research in Parlier suggests 50–70 lbs N per acre in the first season covers the deficit, against the 25–35 lbs a first-year almond orchard would normally get. By the second year, recycled-block trees matched non-recycled growth rates without extra fertilizer.

Worth saying plainly: these are almond numbers, from California, on Hanford fine sandy loam. We've also seen reporting of a UC dry bean trial where yields came in lower following whole orchard recycling — we weren't able to fetch that study directly, so treat it as a flag to ask your farm advisor about your crop rather than a finding to plan around. The mechanism that helps almonds isn't guaranteed to help whatever you rotate into.

Where burning still wins the argument

Disease. Almost universally, disease.

Washington's BMP guidance keeps a dedicated disease control pathway for tear-out burns, requiring the grower to name the disease and strongly recommending verification from a horticultural pest and disease board, a university extension agent, or a state Department of Agriculture pest control specialist. It also adds a timeliness practice: where insects or disease are the driver, piles should be disposed of as quickly as possible to prevent spread.

California's near-total phase-out keeps the same door open from the other side. Diseased material can still get a permit where the county agricultural commissioner determines burning is the only available disposal method, and the Valley grant program funds air curtain burners — but only for diseased material or material with embedded wire, which is why cordon-spur vineyard wood shows up as its own category.

That embedded-wire detail is a genuinely under-discussed problem: trellis wire in vineyard removal material fouls grinders, which is a mechanical reason chipping sometimes isn't feasible even where it's legal. On the disease side, there's a body of viticulture literature reporting that grapevine pruning debris left on the vineyard floor can host trunk-disease inoculum into the following season. We couldn't verify that directly for this article, so take it as a question for your farm advisor rather than a settled fact — but it's the reason "just mulch it" isn't automatically the right answer in a block with a known trunk disease problem.

If you're still burning, burn well

Where prunings or tear-out still qualify, the emissions math is mostly about moisture and pile construction. Washington's BMP guidance recommends curing piles or windrows at least eight months where possible — orchard wood holds a lot of internal moisture and can take that long to dry — and keeping piles clean of dirt and rock, since contaminated piles smolder and produce far more emissions per ton consumed.

The rest is dispersion. Orchard blocks tend to sit near houses, roads, and other blocks, which makes vertical mixing the controlling variable more often than wind speed — see our explainer on mixing height and the broader smoke management guide. If you're coordinating tear-out across several blocks, the burn plan walkthrough is worth an hour, and spring vs. fall burning covers the seasonal tradeoffs that decide when a cured pile is actually ready.

Frequently asked questions

Can I still burn annual prunings in California?

Not in the San Joaquin Valley, with a narrow exception. Surface harvested prunings have been prohibited from open burning District-wide since January 1, 2025; the District may still permit prunings from apple, pear, and quince crops. Other California air districts set their own rules, so confirm with the district covering your county.

Do I need a permit to burn orchard prunings in Washington?

Not an agricultural burn permit from Ecology. Annual orchard prunings sit in the no-permit-needed column alongside fence rows, ditch banks, irrigation canals, and windblown tumbleweeds. You still must notify your local fire protection authority, comply with local bans, and check the daily burn decision — and a statewide emergency ban, like the one in effect through September 30, 2026, overrides the exemption.

Is chipping worth it if I'm not replanting the same crop?

That's the open question. The strong yield and water-use data comes from almond blocks replanted to almonds. Where a different crop follows, results have been more mixed, and nitrogen immobilization in the first season is the consistent cost either way. Ask your county farm advisor about trials in your crop before assuming the almond numbers transfer.

What's the difference between prunings and attrition?

Attrition is the incidental woody material an orchard or vineyard sheds — suckers, dead or broken branches, stumps, trunks, dead trees. Annual prunings and material from a whole-block removal are separate categories and are excluded from attrition, which matters because attrition is one of the few things still burnable in the San Joaquin Valley while prunings and removals generally are not.