Are we solving the wrong problem when we strip away everything under our trees?
By Chuck Schembre
As the orchard industry transitioned into large-scale commercial systems many decades ago, growers faced a new reality: increasing disease and insect pressure. In response, universities, researchers, and crop advisors promoted a practice now widely accepted as standard, orchard sanitation.
Sanitation, in its simplest form, involves removing leaves, prunings, woody debris, and fallen fruit from the tree row. This material is often swept or blown into rows, then shredded, burned, or treated with nitrogen fertilizers to accelerate decomposition. The reasoning is straightforward: this debris serves as an overwintering site for disease pathogens and insect pests. Remove the habitat, and you reduce next year’s pressure.
But what if this approach is addressing the symptom rather than the cause?
A System Out of Balance
From an ecological perspective, orchard sanitation runs counter to how natural systems function. In a forest ecosystem, the model from which orchard systems ultimately derive, trees exist within a rich layer of organic matter: fallen leaves, twigs, and woody debris. This “duff” layer is not waste but the foundation of biological life. Within that layer thrives a complex web of organisms: bacteria, fungi, insects, and other decomposers. Among them are saprophytic fungi, the primary recyclers of organic matter. Importantly, these organisms also play a regulatory role. They compete with and suppress pathogenic species, helping maintain biological balance.
Many of the diseases we aim to control, such as apple scab, pecan scab, and alternaria, can be suppressed and regulated by other key soil organisms. In a functioning ecosystem, these organisms are not eliminated; they are regulated.
The question thus becomes, Why do these diseases become so severe in orchard systems? The uncomfortable answer is that their severity is often a product of the system itself.
How Nature Regulates Disease
In natural systems, plant disease is rarely eradicated; it is kept in check. Saprophytic fungi and other bacteria decomposers rapidly colonize fallen leaves, fruit, and woody material. This colonization is not passive. These organisms physically occupy space, consume available nutrients, and produce biochemical compounds that inhibit or outcompete pathogenic fungi. In effect, they deny pathogens the ability to dominate.
This is the principle of competitive exclusion at work: when a diverse and active microbial community is present, no single organism, pathogen included, can easily proliferate unchecked. Additionally, many soil and residue-dwelling microbes produce antifungal metabolites, enzymes, and signaling compounds that further suppress disease expression. Others induce plant responses that strengthen resistance. The result is not a sterile environment, but a buffered one, where disease pressure exists but is moderated.
When we remove organic residues through sanitation, we are not just removing potential inoculum, we are removing the habitat and food source for the very organisms that regulate that inoculum. In doing so, we may unintentionally simplify the biological system to the point where pathogens face less competition, not more.
Consider how exposed and vulnerable a bare tree row is. Without organic cover, soil aggregation declines, compaction increases — especially with multiple tractor passes in moist conditions — water infiltration is reduced, and oxygen exchange in the root zone is impaired. At the same time, we eliminate a continuous supply of organic matter that would otherwise decompose into plant-available nutrients and fuel microbial life. In essence, we are removing the tree’s natural support system.
There is also a direct economic cost. Sanitation programs often require multiple equipment passes and can exceed $200–$250 per acre. These are resources that could instead be invested in improving plant nutrition, enhancing biological diversity, or implementing targeted integrated pest management strategies.
Nature’s Built-In Pest Control
The case for sanitation often extends to insect management. Remove overwintering sites, and you reduce future populations — whether it’s codling moth in apples or navel orangeworm in almonds and pistachios. This sounds like a good way to reduce harmful insect populations.
Yet in regenerative orchard systems, a different pattern emerges. When orchards are managed with diverse cover crops and minimal disturbance, they begin to function more like ecosystems than sterile production zones. These systems support a wide range of beneficial organisms like predatory insects, birds, and other wildlife that actively suppress pest populations.
Observations from regenerative systems show that fallen nuts and fruit often decompose rapidly, becoming part of the biological cycle. In contrast, in more conventional systems, these materials can persist longer, sometimes harboring pest larvae. The difference is not the presence or absence of residue; it is the presence or absence of a functioning biological community.
The Tree Knows How to Feed Itself
Trees evolved to operate within a cycle of self-renewal: leaves fall, organic matter accumulates, and decomposition returns nutrients to the root zone. This process also fosters symbiotic relationships with soil organisms — relationships that enhance nutrient uptake, resilience, and overall health. By removing this cycle, we interrupt a fundamental biological process.
This is not to suggest that orchards should be unmanaged or treated as wild forests. Commercial production requires structure, efficiency, and consistency. But we now have the knowledge and tools to bridge modern agriculture with ecological principles — to manage orchards in ways that mimic natural systems rather than oppose them. The important thing isn’t to eliminate diseases and pests but to consider why they’re thriving in the first place. If an orchard system is heavily reliant on sanitation to remain productive, it may be an indication of a deeper imbalance, rooted in poor soil health, lack of biological diversity, or unwise system design.
Sanitation may offer a short-term reduction in visible pressure. But it may also contribute to long-term instability by weakening the very systems that naturally regulate disease and pests. Practices that build organic matter, protect soil, and enhance biological diversity can create orchard systems that are more resilient, less dependent on intervention, and better aligned with how trees function in nature.
In the end, the health of the orchard is not determined by how “clean” the ground is managed, but by how well the soil beneath it functions.
