By John Pirrung, Field Technician; SWNYDLFC

Rounding out the final article in this series on till vs no-till, we're finally focusing on how your tillage decisions can impact the pest pressures on your farm. Pests, in the broadest sense, include weeds, insects, and diseases; each of these will require different management tactics and will respond differently to your tillage practices. How growers choose to till (or not) can shift the pest risk profile, improving control of one pest while potentially turning another into a bigger challenge. On top of all of this, it's important to consider beneficial organisms like pollinators and how management decisions impact them as well.

WEEDS:

Tillage

Benefits:

· Tillage buries weed seeds deeper, which can reduce germination of shallow-emerging species

· Mechanical disruption kills many existing weeds and exposes weed seed banks to predation or decay

Challenges:

· Tillage can bring buried seed banks closer to the surface, potentially resurfacing species with high seed longevity (ex. Lambsquarters)

· Weeds that reproduce with rhizomes may require several passes of mechanical disruption to be properly controlled (ex. Canada Thistle, Bindweeds, Johnsongrass)

No-till

Benefits:

· Weed seeds remain near the soil surface where decay and predation by insects/rodents can be higher

· Soil surface residue can physically suppress weed emergence and can delay germination by keeping soil cooler for longer

Challenges:

· The species spectrum of weeds can shift, favoring small-seeded weeds and shallow-germinating species

· Reduced disturbance means that some weeds, especially creeping perennials, can be more difficult to control, even with herbicides

Tips for Growers

If switching to no-till, plan to take inventory of your weed seed bank, emphasize early-season weed control (ex. herbicide burndown), and expect a shift in prominent weed species.

INSECTS (& OTHER ARTHROPODS):

Tillage

Benefits:

· Tillage physically disrupts soil-dwelling or residue-inhabiting insect pests by, for example, burying or destroying overwintering stages

· By eliminating a protective residue layer, habitat for organisms such as slugs is reduced, exposing them to predators

Challenges:

· The same disruption and removal of residue can also reduce habitat and refuge areas for beneficial predators and pollinators

No-till

Benefits:

· No-till fields are often accessible sooner after rainfall events, allowing for more timely herbicide application

· A habitat composed of residue and cover crops can enhance insect biodiversity, increasing natural pest suppression

Challenges:

· Some pests may increase or have their emergence periods change because of cooler, wetter soils that favor their survival

Tips for Growers

In a low- or no-till system, plan for thorough insect scouting, pay attention to habitats for both pests and beneficials, and aim to integrate residue management, crop rotation, or cover crops to manage insect populations.

DISEASES:

Tillage

Benefits:

· Incorporating and burying crop residue reduces surface inoculum for some foliar or residue-borne diseases

· Earlier soil warming and drying in tilled fields may make the environment less favorable for pathogens that prefer cool and wet soils

Challenges:

· Intensive tillage can damage soil structure and microbial communities, potentially reducing natural disease suppression capacity over time

No-till

Benefits:

· A more stable soil environment with higher microbial activity may support natural disease suppression through increased microbial abundance and diversity

· Leaving residue can help retain organic matter, supporting more habitat for beneficial microbial populations that can suppress pathogens

Challenges:

· Surface residue can act as a reservoir for certain types of foliar pathogens to survive from one season to the next

· Weeds can serve as alternative hosts for some pathogens; since no-till fields can see stronger pressure from many weeds, these can host more pathogens

Tips for Growers

In planning tillage strategy, consider the crop and disease history of the field, and how crop residues are managed; If using no-till, focus on variety resistance and cover crop management, and note that early planting conditions become more important.

TAKEAWAYS:

When it comes to pest management, tillage decisions are not a binary; rather, any choice will simply change the pest risk profile and thus the necessary management practices.

· Conventional tillage gives you mechanical weed knock-down and residue burial (helping some pests/diseases) but it also disturbs soil/residue habitat (potentially harming beneficials) and may shift weed seed banks or damage soil health over time

· Reduced or no-till preserves residue, supports soil structure, moisture retention and beneficial organisms, but also may increase risk of certain pests (slugs, wireworms, residue-borne diseases), and shift weed species toward more shallow‐germinating types, calling for different weed/insect/disease strategies

HOW SHOULD YOU PLAN?

1. Assess field history: What weeds, pests and diseases keep coming back? What is the residue situation, drainage, soil warming?

2. Design for beneficials: If reducing tillage, aim to actively build habitat for beneficial insects/pollinators (flowering strips, cover crops, buffer zones, etc.).

3. Align tillage choice with integrated pest management (IPM): Regardless of tillage system, rotation, variety selection, scouting, and timely interventions remain crucial.

Sources

· https://extension.psu.edu/an-i...

· https://extension.umn.edu/soil...

· https://extension.unh.edu/blog...

· https://extension.missouri.edu...

· https://extension.okstate.edu/...

· https://extensionpubs.unl.edu/...