118 VEN Root Diseases of Grapevine in California and their control
Root Diseases
Vine Declines Phaeoacremonium aleophilum (Togninia minima) Phaeomoniella chlamydosporum Armillaria Root Rot Phytophthora Root Rot Black Foot Phymatotrichum Root Rot Verticillium Wilt
Vine Declines
Young vines
Nursery involvement
Symptoms
External-root rot, dieback, decline, foliage firing, fruit raisining Internal-vasc discoloration, drying, pith blackening
Pathogenicity
Soilborne inoculumPc= chlamydospores, Pa= (perithecia??) Entrance thru non-wounded epidermis, wounds in bark or roots
Rootstock susceptibility
Phylloxera resistant rootstocks are more susceptible
Stress Predispositon
Disease always associated with either water deficit, early/heavy fruiting, or poor planting (J rooting)
Many vineyards have been
removed because of Petri disease and vine decline caused by Phaeoacremonium spp. and Pa. chlamydospora
Armillaria Root RotA. mellea
Prevalent in north coast area Associated with forest (oak) removal Root to root spread Infection centers occur in vineyards Signs Thick, white to cream colored mat of vegetative fungal tissue (mycelial fans) beneath bark. Symptoms Stunted growth, rapid dessication, rapid death Root rot dry, punky
Range of Armillaria mellea
Native hosts Douglas-r Incense-cedar Coast Live Oak CA Black Oak Valley Oak Tanoak Madrone Planted Hosts Landscape trees/shrubs Orchard trees Grapevines
Control of Armillaria Root Rot
Expose crown area and upper roots of
vines to air during the summer months. Do not plant vineyards on oak studded hillsides. Fumigants Fungicides???
Exposing crown and upper roots of infected vines
Black FootCylindrocarpon destructans
Identification and Control of Cylindrocarpon species causing Black-foot disease California in Symptoms Root rot
Vascular plugging
Vine stunting (Mendocino County)
Causal Agent of Black Foot Disease
Ascomycetes Hypocreales Nectriaceae Cylindrocarpon (T: Neonectria)
Cylindrocarpon destructans
Cylindrocarpon obtusisporum
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Endomycorrhizal Control of Black Foot Disease
Zygomycetes GlomalesGlomaceaeGlomus Isolates used : -Glomus intraradices -Glomus clarum Isolates chosen because: -shown to protect against C. destructans on other crops -good infectivity of grapevine roots
Endomycorrhizal Control of Black Foot Disease
Initial inoculum population estimated by:
Percentage of root colonization
Counting spores in the soil
Black Foot Control
Phytophthora Root and Crown Rot
Young plants Heavy, poorly drained soils Rootstock susceptibility?
Phytophthora contd
Phytophthora contd
Pathogenicity 24-48 hrs of saturated soil needed for infection Effect of temperature Effect of time of year Control Plant on berms to allow drainage away from crowns. Irrigation management
Pulse irrigations
Pathogenicity of selected Phytophthora (Ph.) and Pythium (Py.) species on hardwood cuttings of St. George rootstock (Greenhouse Exp. Apr-Jul 1998)
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Pathogenicity of selected Phytophthora (Ph.) and Pythium (Py.) species on hardwood cuttings of cv. Aramon (Greenhouse Exp. Apr-Jul 1998)
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Susceptibility to Phytophthora cinnamomi in grape rootstock germplasm
Among the more than 20 grape rootstocks and
germplasm selections evaluated for resistance to Phytophthora cinnamomi in greenhouse tests, only Vitis rupestris cv. St. George was consistently susceptible to the pathogen greenhouse is consistent with field observations and lab diagnoses for diseased grapevines in Californias central coast vineyards
The susceptibility of St. George to P. cinnamomi in the