Root Disease Oomycetes
Overview:
-
These are NOT fungi**
- …but called ‘water molds’
- Cell walls are cellulose based, not chitin based like fungi & insects
- Require Oomycete specific materials [Oomycides]
- Often no root hairs / thick roots
- Dark discoloration
- Outer root tissue sloughs off easily
- ‘Sheath pulls off easily”
- AKA ‘Rat tail’
- Sunken cankers on roots
- Dig around – if you pull sapling the diagnostic roots will pull off
- Brittle, break easily
Phytophthora/Phytopythium Symptoms:
- Slow decline or rapidly apparent death
- Leaves/needles: turn straw, cinnamon brown (stay on), curl
- Branches – Single, groups, all, discoloration starting near crown
- Stem – Cankers, wood dark streaks, bark pulling away
- Resembles drought/nutrient stress – watering/fertilizing makes it worse!
Management:
Cultural Practices:
- Inspect plants before planting them
- Ensure proper sanitation practices for equipment, benches, and floors
- Improve soil drainage and reduce instances of standing water
- Avoid over watering
- Increase soil organic matter content
- Remove and destroy infected plants
- Replace infested soil
- Plant resistant varieties
- Soil solarization
- Use wood chip mulch
- Crop rotation / site rotation
Materials:
- Protectant and Local Translaminar:
- Cyazofamid [21]
- Dimethomorph, Mandipropamid [40]
- (and combinations)
- Xylem Mobile Systemic (upwards):
- Mefenoxam [4]
- Fluopicolide [43]
- Fenamidone [11]
- Oxathiapiprolin [49]
- Amphimobile/Fully Systemic:
- Aluminum tris (O-ethyl phosphonate) [P07]
- Mono- and di- potassium salts of phosphorus acid [P07]
- Biorationals:
- Streptomyces lydicus [BM02]
- Trichodermaasperellum [BM02]
- Bacillus subtilis strain QST713 [BM02]
- Hydrogen peroxide and peroxyacetic acid [NC]
- Quaternary ammoniums
- Considerations:
- ROTATION IS CRITICAL
Disclaimer – Materials do not cover all possible control scenarios and are intended for licensed professionals. Tradenames do not imply endorsement and are used as examples. You must strictly follow the label for each compound prior to use. Rutgers is not responsible form is used materials or damages thereof. The label is the law. Labels will provide detailed information on use and restrictions. Additionally, application intervals, compatibility, surfactant use, PHI, PPE, important and other key information is described in detail. Always discuss treatments with your local agents. Note: Neonicotinoids can only be legally applied in commercial agriculture settings by licensed applicators. Guidelines and recommendations made in this presentation are specific to the state of New Jersey.