Here’s a detailed and categorized catalog of root diseases affecting a wide range of plants—from ornamentals to crops—based on pathogen type, with symptoms, conditions, hosts, and treatment guidelines.
🦠 1. Fungal & Fungal-like (Oomycetes) Root Diseases
Disease | Pathogen(s) | Hosts | Symptoms | Conditions Favoring | Treatment |
---|---|---|---|---|---|
Phytophthora Root Rot | Phytophthora spp. (e.g., P. cinnamomi, P. sojae, P. parasitica) | Avocado, soybean, ornamentals, citrus, forest trees | Brown/black mushy roots, stem rots, sudden wilting, stunting | Poor drainage, warm/wet soils hortsense.cahnrs.wsu.edu+5toxicfreefuture.org+5ag.umass.edu+5en.wikipedia.org+15hort.extension.wisc.edu+15cropprotectionnetwork.org+15en.wikipedia.orgcropprotectionnetwork.org+1growertalks.com+1 | Metalaxyl, Fosetyl‑Al, phosphonates, improved drainage |
Pythium Root Rot / Damping-Off | Pythium spp. (e.g., P. ultimum) | Seedlings, ornamentals, vegetables | Water-soaked, soft roots, damping-off | Overwatering, low O₂ | Propamocarb, mefenoxam, sanitation, avoid overwatering |
Fusarium Root Rot | Fusarium solani, F. oxysporum | Tomato, beans, soybean, ornamental bulbs | Brown streaks on roots, stunting | High temps, poor soil | Carbendazim, Trichoderma, rotation |
Rhizoctonia Root & Crown Rot | Rhizoctonia solani | Rice, potatoes, vegetables, ornamentals | Sunken, dry lesions at collar | Warm, moist soils | PCNB, soil solarization |
Sclerotinia (Southern Blight) | Sclerotium rolfsii | Southern crops | Rotted roots, white mycelial fan | Warm/compacted soils | Fungicides, burn debris |
Armillaria / Shoestring Root Rot | Armillaria mellea | Trees/shrubs | Root decay, white mycelium under bark | Moist forest soils | Remove infected roots/stumps |
Black Root Rot | Thielaviopsis basicola | Vegetables, floriculture | Blackened root segments | Temperate/pooled water | Fungicides, pH adjustment |
Aphanomyces Root Rot | Aphanomyces euteiches | Legumes (pea, bean) | Grey, water-soaked, rotten roots | Cool, wet soil | High-quality rotations, resistant varieties |
🧫 2. Bacterial Root Diseases
Disease | Pathogen | Hosts | Symptoms | Conditions | Treatment |
---|---|---|---|---|---|
Bacterial Soft Rot (Erwinia spp.) | Erwinia carotovora | Carrot, potato, ornamentals | Soft, foul-smelling roots en.wikipedia.org+10apsnet.org+10en.wikipedia.org+10thespruce.com+1growertalks.com+1 | Waterlogged, warm soil | Sanitation, drainage |
Crown Gall | Agrobacterium tumefaciens | Grapevine, fruit trees | Swollen, gall-like roots | Wounds, graft sites | Resistant rootstocks, hygiene |
🐛 3. Nematode-Induced Root Disorders
Disease | Nematode Species | Hosts | Symptoms | Control |
---|---|---|---|---|
Root-Knot Nematode | Meloidogyne spp. | Many crops | Swollen galls, stunting thespruce.comcropprotectionnetwork.org+13en.wikipedia.org+13thespruce.com+13 | Nematicides, rotation, resistant varieties |
Lesion Nematode | Pratylenchus spp. | Vegetables, ornamentals | Root necrosis, bronzing | Fumigation, organic matter |
Stubby-Root Nematode | Trichodorus spp. | Field crops | Short, stubby roots | Soil fumigation |
🌱 4. Physiological and Environmental Root Disorders
Disorder | Cause | Hosts | Symptoms | Solution |
---|---|---|---|---|
Asphyxiation (Waterlogging) | Flooded soil, poor drainage | Most crops | Blackened roots, wilting ag.umass.edu+4thespruce.com+4hort.extension.wisc.edu+4southernliving.com | Improve drainage, raised beds |
Salt Damage | High soil salinity | Rice, onions | Burned root tips | Leaching salts, gypsum |
Compaction | Heavy machinery | Field crops | Shallow, restricted roots | Aerate, add organic matter |
Chemical Burn | Herbicide/over-fertilizing | Container plants | Necrotic roots | Leach soil, flush fertilizer |
🥕 5. Nutrient Deficiency–Related Root Issues
Deficiency | Symptom in Roots | Affected Plants | Correction |
---|---|---|---|
Phosphorus (P) | Poor branching | Vegetables, cereals | DAP, organic P amendments |
Calcium (Ca) | Weak root tips | Tomatoes, fruit | Lime, CaNO₃ foliar |
Nitrogen (N) | Sparse shallow roots | Leafy greens | Urea, compost |
Iron (Fe) | Limited root health | Citrus, legumes | Chelated Fe |
Zinc (Zn) | Reduced root elongation | Maize, bean | ZnSO₄ foliar |
📊 Summary
Fungal/root-rot pathogens (Phytophthora, Pythium, Fusarium, Rhizoctonia, Armillaria) are the most destructive, especially under wet soil conditions.
Bacterial and nematode disorders can cause severe root damage—often exacerbated by stress.
Environmental and nutrient issues are widespread but often misdiagnosed as disease; these require different management.
Preventive measures: use disease‑free planting material, improve soil drainage and structure, rotate crops, maintain balanced fertilization, and apply appropriate fungicides/nematicides based on diagnosis.