Pyroligneous Acid and Seaweed Extract Increase Haskap Berry Yield

Introduction

Haskap (*Lonicera caerulea L.*), also known as honeyberry, is a nutrient-rich berry crop with growing investment potential in Canada. However, optimal cultivation practices for haskap remain under-researched. One promising approach to improving plant growth, yield, and disease resistance is the use of biostimulants such as pyroligneous acid (PA) and liquid seaweed extract (LSE). This study investigates the effects of varying application frequencies and rates of PA combined with LSE on haskap growth, berry yield, and powdery mildew management.

Experimental Design and Application

A field study was conducted at North 45 Orchards in Cloverdale, Nova Scotia, over two growing seasons. Haskap 'Indigo Gem' plants were treated with different concentrations of PA (2%, 4%, 6%, 8%, and 10%) combined with 0.35% LSE. Applications were performed weekly, bi-weekly, and tri-weekly. Control treatments included water alone, PA alone (4%), and LSE alone (0.35%). Foliar sprays were applied manually using a sprayer until runoff, avoiding rainy days to prevent wash-off.

Key Findings

Plant Growth and Photosynthetic Activity

  • Tri-weekly application of 2% and 4% PA + LSE significantly increased fresh and dry leaf weight, anthocyanin content, flower count, and photosynthetic efficiency.
  • Weekly application of 10% PA + LSE improved chlorophyll content and enhanced photosynthetic activity (Fv/Fo ratio), indicating increased plant vigor.

Berry Yield and Quality

  • The highest yield increase (90.7%) compared to control was observed with the 8% PA + LSE treatment.
  • Tri-weekly application resulted in a 95% yield increase compared to weekly applications.
  • Berry quality, including total soluble solids and maturity index, improved with 2%, 4%, and 6% PA + LSE treatments.

Disease Resistance

  • Weekly applications of 10% PA + LSE reduced powdery mildew incidence and severity by 8.3%.
  • Increased electrical conductivity and nutrient content in leaves suggested enhanced plant defense mechanisms.

Implications for Haskap Cultivation

This study highlights the potential of PA and LSE as effective biostimulants for haskap production. The findings suggest that tri-weekly applications of 2–4% PA + LSE are optimal for enhancing growth and yield, while higher concentrations (10%) are beneficial for disease suppression. Future research should focus on understanding the biochemical mechanisms behind these benefits and optimizing application methods for commercial-scale production.

Article based on: Haskap (Lonicera Caerulea L.) Plant Response to Varying Frequency and Rate of Pyroligneous Acid with Added Liquid Seaweed Extract