Project Overview

Reports

Commodities

Target Pests

Practices

The frequency and intensity of high-severity wildfires in the western U.S. have increased dramatically, creating an unprecedented demand for reforestation seedlings. NOAA predicts a six-fold increase in large wildfire risks by 2050, with serious implications for American forests and related industries. In 2024 alone, wildfires in California impacted over one million acres, with significant losses also recorded in Washington and Oregon. Reforestation efforts are crucial for restoring environmental, ecological, and economic services. Private nurseries, which account for 83% of seedling production in the western U.S. region, play a vital role in this process.

However, nursery seedling production efforts face significant threats from soilborne pathogens such as Fusarium spp., Cylindrocarpon spp.. For example, Cylindrocarpon caused a 74% loss of a Douglas-fir seedling lot at the Silvaseed Company in 2022. Current management options are limited, particularly in bare root nurseries, where only two fungicides are available, Clearys 3336 and Tourney E, to manage Fusarium spp. in Douglas-fir, Z, and Clearys 3336 and Dithane 75 are recommended for the management of Cylindrocarpon spp.based on plate assays. Overuse of these products raises concerns about resistance development. 

Chitosan, a polysaccharide derived from crustacean shells, offers a promising alternative for managing soilborne diseases. Studies demonstrate that chitosan can reduce fungal growth, alter pathogen morphology, and trigger plant defense mechanisms. Applications of chitosan have improved survival rates in forestry seedlings infected by damping-off pathogens and increased drought tolerance. Despite its potential, research on its operational efficacy in conifer nurseries remains limited. 

This project aims to evaluate the efficacy of chitosan (Tidal Vision Spectra) compared to conventional fungicides (Clearys 3336,  Dithane 75, and Tourneys EZ) in managing soilborne diseases in Douglas-fir seedlings in greenhouse and field settings. 

1. Compare the inhibitory effects of Clearys 3336, Dithane 75, Tidal Vision Spectra at high and medium concentrations on the growth of Cylindrocarpon and Fusarium spp. with plate assays.
2. Assess Product Efficacy in Greenhouse Settings 
   1. Quantify the impact of product treatments on disease incidence, severity, and tissue colonization by Cylindrocarpon and Fusarium spp. in Douglas-fir (Pseudotsuga menziesii) seedlings grown under controlled greenhouse conditions.
   2. Determine product efficacy for mitigating Cylindrocarpon and Fusarium spp. infection on seedlings of different growth stages in controlled greenhouse conditions.
3. Validate Greenhouse Findings in Field Conditions
   1. Evaluate product efficacy in managing Cylindrocarpon and Fusarium spp. in field trials with disease-free seedlings subjected to inoculated soils.
   2. Compare efficacy of product treatments (Cleary’s 3336, Dithane 75, Tidal Vision Spectra) in multiple field environments to account for variability in soil environmental conditions (temperature, structure, total naturally occurring population).