Maleic hydrazide (MH) is a plant growth regulator used on potatoes before harvest to suppress post-harvest sprouting and extend dormancy. When the timing window is correct, coverage is even, and storage parameters are disciplined, MH reduces sprout initiation, limits weight loss, stabilizes grading, and supports consistent processing quality across long supply chains. This guide explains MH × Potato end-to-end—mechanism, timing principles, storage integration, quality outcomes, compliance, and FAQs—without prescribing dosage or off-label practices.
What Is Maleic Hydrazide?
Maleic hydrazide is a plant growth regulator that primarily inhibits mitosis (cell division) in meristematic tissues. In potatoes, MH is deployed as a pre-harvest sprout suppressant to keep tubers dormant longer through curing, storage, and transport.
Identity & use context
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Common name: Maleic hydrazide (MH)
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Functional class: Plant Growth Regulator (PGR)
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Intended outcome: Delay sprouting; extend dormancy; lower storage losses
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Compliance: Subject to local registration and MRLs (maximum residue limits). Always follow the registered label.
This document provides management principles only. It does not provide dosage, tank mixes, or step-by-step operational instructions.
Potato Physiology: Why Sprouting Happens After Harvest
Potato tubers remain physiologically active after harvest. As storage temperature, relative humidity, gas composition, and time interact, dormant buds can re-activate. The results are:
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Sprouting → downgraded appearance and out-of-spec lot rejections
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Increased respiration and dry-matter loss → measurable shrink
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Processing variability → sugar accumulation swings that affect fry color and yield
Programs that target both biological drivers (sprout initiation) and environmental drivers (temperature, humidity, O₂/CO₂, airflow) achieve the most repeatable outcomes.
How MH Works on Potato
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Mode of action: MH reduces cell division at bud meristems, delaying the switch from dormancy to active sprout growth.
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Dependencies: Efficacy is moderated by cultivar, skin set/maturity status, application timing, canopy coverage/penetration, and post-harvest storage conditions.
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Expected results (under good practice): lower sprout incidence and sprout length over time, reduced weight loss linked to sprouting/respiration, more stable grading, and more predictable processing parameters.
MH is a system component, not a replacement for storage engineering. It curbs biological intent to sprout; the store curbs environmental permission to deteriorate.
Application Window & Field Discipline (Principles Only)
Objective: maximize sprout suppression while protecting quality.
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Maturity/skin set: Target the pre-harvest window when skin set is secure and vines are approaching natural senescence or are scheduled for vine-kill.
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Timing consequences:
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Too early → potential impact on size/marketable yield; residue inefficiency.
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Too late → diminished sprout control; operational conflicts with harvest or vine-desiccation.
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Coverage logic: Even canopy coverage; appropriate penetration into the lower canopy; avoid both untreated pockets and excessive overlap.
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Traceability: Record cultivar, maturity markers, field block, application batch, harvest date, storage location, and inspection data (sprout incidence, sprout length, shrink, sugar metrics where relevant).
Use only per label. Confirm any intervals, restrictions, and compatibilities on the registered product.
Storage Integration: MH ≠ Cold Store Replacement
High-performing programs align MH with disciplined storage management:
Core storage parameters
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Temperature: Maintain the target setpoint for the market class (table vs. processing), balancing dormancy with sugar management.
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Relative humidity: Keep RH in the recommended range to limit dehydration while avoiding conditions favoring disease.
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Airflow/ventilation: Engineer air paths through boxes/bins/pallets; avoid dead zones.
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Sanitation & curing: Adequate skin cure and clean handling reduce entry points for pathogens.
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Monitoring: Scheduled checks for sprout incidence/length, weight loss, disease, and—where relevant—reducing sugars/fry color.
System view: Field window → curing/drying → grading → climate control → periodic QC. When all links are aligned, losses drop in a repeatable, auditable way.
Quality & Processing Outcomes
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Appearance & grading: Delayed sprouting and shorter sprouts support stable grades and fewer downgrades.
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Physiological loss: Lower sprouting and moderated respiration reduce shrink.
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Processing suitability: With correct timing and storage, programs maintain or improve fry color consistency and overall processing predictability (cultivar-dependent).
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Risk guardrails: Off-window or beyond-label practice can undermine benefits and increase soft-rot or quality variability. Window discipline matters.
Risk & Compliance
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Label limits: Respect label timing and restrictions; these exist to balance efficacy, residue compliance, and quality risk.
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MRLs & market access: Destination markets have different MRLs and use patterns. Align sampling plans, third-party tests, and documentation with buyer and regulatory requirements before shipment.
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Compatibility & sequencing: If coordinating with vine-kill or pre-harvest fungicide programs, plan sequence and compatibility. Avoid unverified tank mixes.
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Data integrity: Maintain batch IDs, retain samples where required, and standardize inspection forms for traceable, evidence-based decisions.
Procurement & Technical Documentation Checklist
Use a structured checklist to avoid bottlenecks later:
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Product identity: Maleic hydrazide intended for pre-harvest sprout suppression in potatoes
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Regulatory fit: Registration status and permitted uses in the production and destination countries
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MRL alignment: Target-market MRLs; agreed test methods; sampling plan prior to shipment
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Documentation: COA, MSDS, and label in applicable languages
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Storage program: Temperature/RH targets, airflow design, sanitation SOPs, monitoring cadence
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Traceability: Lot numbers, fields/blocks, application dates, storage locations, inspection logs
Frequently Asked Questions
Q1. If MH is used, do I still need active temperature and humidity control?
Yes. MH limits sprout biology; storage engineering controls environmental drivers. Both are essential for consistent, low-loss outcomes.
Q2. Will MH affect fry color or processing yields?
Outcomes depend on timing, cultivar, and storage parameters. Under correct timing and disciplined storage, programs aim to stabilize reducing sugars and fry color. Validate on representative lots first.
Q3. Can MH be applied in the same pass as vine-kill or fungicides?
Only as permitted on the label and after confirming compatibility and sequence. When uncertain, separate operations and consult official guidance.
Q4. Do all cultivars respond equally?
No. Response varies. Pilot treatments to establish a cultivar–window–storage baseline, then scale once performance is demonstrated.
Q5. How do I minimize soft-rot risk?
Stay within label boundaries, respect the timing window, ensure proper curing/drying and clean handling, and maintain storage temperature, RH, and airflow in target ranges.
Conclusion
Maleic hydrazide is a proven lever for extending dormancy and suppressing sprouting in potatoes. Its benefits compound when three conditions are met: correct timing, even coverage, and disciplined storage control. Treat MH as a critical component in an integrated system—from field to store—to deliver repeatable quality, lower shrink, and more predictable commercial performance.
Post time: Nov-10-2025
