VEN 118 Vine Pest/Disease Midterm UC Davis Fall 2018
What are the traits of muscadinia rotundafolia?
"holy grail" of grape breeding, resistant to nematodes and phylloxera and foliar diseases, does not root from dormant cuttings, not easily bred with vinifera (has 40 chromosomes compared to vinifera 38)
What is the phomopsis viticola disease cycle?
*long wet period are required for sporulations and infections *pycnidia (contains conidiophores) on bleached canes -spores are released in large quantities from the overwintering pycnidia on diseased canes and spurs -the more infected canes that are retained at pruning, the greater the inoculum and the disease development -infections generally occur when shoots begin to grow -spores are splashed by rain onto early developing shoots and infection occurs when free moisture remains on the unprotected green tissue for many hours -most severe in northern grape-growing regions (North Coast and northern San Joaquin Valley) where spring rains are common after budbreak
What are the black foot management practices?
*planting uncontaminated stock and by avoiding planting in heavy badly drained soils no specific fungicides cultural (drainage in heavy soils can be accomplished by planting on berms and by moving drip irrigation emitters away from the vine), rootstock (all phylloxera-resistant varieties show some level of susceptibility to black foot disease), biological (ex. inoculations with the mycorrhizal fungus Glomus intraradices before planting)
What is cleistothecia?
-> asci -> ascospores *primary infections 12-15 hours of continuous leaf wetness (2 mm rainfall) are required when average temperatures are between 10- 15C (ascospores are released at 10 - 30C)
What are the petri disease management practices?
-chemical: pruning wound protections, treatment of propagation material, protective treatment during grafting -hot-water treatments of propagation material -biological (ex. trichoderma spp. and glomus intraradices -host-resistance
What is the cylindrocarpon spp. disease cycle?
-poorly drained and soil is compacted -most widespread in the north coast probably because it is a cool temperature climate -fungus infects its host through natural openings or wounds on the roots or through the crown of the rootstock -fungus invades lignified tissues of the plant, which produces root lesions and subsequent plugging of the xylem by fungal tissue, gums and tyloses - reduced mineral and water uptake results in plant dieback -pathogen overwinters as chleistothecia, spread as spores carried by water favored by: -malnutrition, poor water drainage, soil compaction, heavy crop loads on young plants, planting of vines in poorly prepared soil and improper plant holes -soil compaction and/ or poor soil preparation will most likely contrib- ute to poor root development (j-rooting) -high temperatures during summer also play an important role in symptom expression
Why do we use rootstock selection?
-resistance to present and potential soil pests -suitable for the soil's texture, depth, and fertility -compatible with soil chemistry (pH, salinity, lime content) -favored for the anticipated soil water availability, drainage, and irrigation practice -appropriate for the vineyard design -appropriate for the fruiting variety's growth and fruiting characteristics
What are the powdery mildew management strategies?
-season-long control is dependent upon reducing early-season inoculum and subsequent infection -treatment must begin promptly and be repeated at appropriate intervals -all powdery mildew fungicides are best used as protectants -frequency of treatment thereafter depends on fungicide choice and weather conditions -monitor and use the powdery mildew index (PMI) model to determine necessary spray intervals -discontinue the use of soft chemistry products (biologicals, systemic acquired resistance products, and contact materials) when disease pressure is high because by themselves they will not provide adequate control -basal leaf removal can improve coverage and efficacy of powdery mildew fungicides on clusters
Difference between primary vs. secondary infections?
1. first infection of a plant by over-wintering or over-summering pathogens 2. any infection caused by inoculum produced as a result of a primary or subsequent infection
What is the erisyphe (uncinula) necator disease cycle
1. overwintering -fungal growth on diseased buds -spore-bearing resting bodies (cleistothecia), which form in mid summer and develop in Fall on the surface of infected leaves, stems, and bunches 2. first infections -fungal growth in diseased buds results in 'flag shoot' infections, young growing shoots become distorted, grey colored, and curl upwards, spores (conidia) are produced rapidly and dispersed to the rest of the canopy -cleistothecia in the bark produce spores (ascospores) which infect the lower leaves of the shoots 3. spread -infection cycle (from conidia germination to next sporulation) require 5 - 10 days (depend on temperature) *first 18 hours are critical for the establishment of successful infections
What is the botrytis cinerea disease cycle?
1. overwintering -overwinters in decaying plant debris and as black resting bodies (sclerotia) -sclerotia occur on infected areas (dead canes or mummified berries) 2. primary infection -conidia produced from plant debris and sclerotia are spread by wind -infections require free water for a definite period of time depending on temperature -young shoots and clusters may also become infected -infections may occur during bloom if rains occur -infected flower parts can become further source of infection 3. spread -berries that have been damaged by insects, birds, machinery, etc. may become infected at any time after the fruit begins to ripen.
What are the three parts to the disease triangle?
1. pathogen 2. host 3. environment, for a plant disease to occur the plant and the pathogen must come into contact and interact, plant must be susceptible to the pathogen (either variety, species, or at the right stage of development), pathogen must be capable of infecting the plant, environment must favor the growth, virulence, and dispersal of the pathogen and limit plant resistance
What is the phytophtora spp. (oomycete) disease cycle?
24 - 48 hrs of saturated soil needed for infection, most common in vineyards with standing water, seen on young vines under drip irrigation can survive in soil for many years, existing as a saprobe in the absence of living host spore stages: sporangia - produced under saturated conditions zoospores - biflagellate spores produced from sporangia (10-30/sporangium) MOBILE oospores - sexual spores produced by a single isolate in homothallic species and requires two mating types (A1 and A2) in heterothallic species
What is contained in the genus vitis?
60-70 species, 2 groups: eurasian and American, all can be interbred (hybrids)
Armillaria mellea
What is the pathogen that causes Armillaria root rot?
Botrytis cinerea
What is the pathogen that causes Bunch rot?
Plasmopara viticola
What is the pathogen that causes Downy mildew?
Togninia minima, Phaeomoniella chlamydospora
What is the pathogen that causes Esca?
Eutypa lata
What is the pathogen that causes Eutypa dieback?
Diaporthe ampelina
What is the pathogen that causes Phomosis cane and leaf spot?
Phytophthora spp.
What is the pathogen that causes Phytophthora root rot?
Erysiphe necator
What is the pathogen that causes Powdery mildew?
Aspergillus spp. , Penicillium spp.
What is the pathogen that causes Sour rot?
Armillaria root rot
What is this Pathogen?
Bunch rot
What is this Pathogen?
Downy Mildew
What is this Pathogen?
Esca
What is this Pathogen?
Eutypa dieback
What is this Pathogen?
Eutypa dieback/Dead arm
What is this Pathogen?
Phomopsis cane and leafspot
What is this Pathogen?
Phytophthora root rot
What is this Pathogen?
Powdery Mildew
What is this Pathogen?
Sour rot
What is this Pathogen?
Difference between biotrophs vs. necrotrophs?
biotrophic pathogens (or obligate parasite): organisms that can live and multiply only on a living plant tissue necrotrophic pathogens (or obligate parasite): organisms that feed only on dead plant tissues
What are the botrytis bunch rot management practices?
canopy: -good control with canopy management and leaf removal -removal of basal leaves or basal lateral shoots at or immediately after berry set has resulted in significantly reduced incidence and severity of disease -warmer growing areas, be careful not to remove excessive numbers of leaves, which can lead to sunburned fruit -condition is made worse when leaves are removed later in the season - if leaves are removed at cluster set, the berries acclimate readily to the sunlight and develop a thick cuticle that helps prevent sunburn as well as Botrytis infection fungicides: -number of spray applications necessary to control bunch rot depends upon: disease pressure in the vineyard, weather conditions, susceptibility of the cultivar (cuticle thickness and morphology, cluster architecture, other susceptibility factors) -key timings for Botrytis fungicide applications are bloom, just before bunch closing, veraison and pre-harvest. Botrytis control becomes more difficult as the grapevine matures because heavy canopy growth and bunch closing make it difficult to place the fungicide where it is needed. -use a full program in vineyards where bunch rot was a serious problem in the previous year, and where sanitation measures were not taken after harvest -fewer applications may be needed if weather is very dry and/or disease pressure is low -number of sprays can be reduced in vineyards with a history of low disease levels and for all vineyards in dry years -treatments are important for table grapes to reduce post-harvest rotting other: growing season-avoid overhead irrigation and keep irrigation periods as short as possible, prevent excessive vine growth by judicious use of water and fertilizer, prevent berry damage by effective control of powdery mildew early in the growing season, minimize berry damage by birds and insects. dormant season-reduce carry-over of botrytis to the next season by removing any remaining fruit from the vines during pruning. If practical, remove trash from the vineyard floor
What are the symptoms of armillaria root rot?
causal organism: amillaria mellea symptoms: stunted growth, rapid dessication, rapid death; dry root rot sings: thick, white to cream colored mat of vegetative fungal tissue (mycelial fans) beneath bark
What are the symptoms of botrytis bunch rot?
causal organism: botrytis cinerea symptoms: shoot-patches of soft brown rot develop on young shoot stems canes-resting sclerotia on dormant canes flower-gray mold growth on infected flower parts fruit-bunches with grey mold growth
What are the symptoms of black foot disease?
causal organism: cylindrocarpon spp. symptoms: -primary infections of roots and basal ends of grafted cuttings in nursery soils -young vines up to eight-years-old are primarily affected by the disease (associated with young nursery vines) -decline and dieback disease -necrotic root lesion -reduced growth and leaf chlorosis
What are the symptoms of powdery mildew?
causal organism: erisyphe (uncinula) necator symptoms: young shoots-distortion and stunting of young grape leaves on the growing shoot leaves-initial symptoms appear as chlorotic spots on the upper leaf surface, signs of the pathogen appear a short time later as white, webby mycelium, as spores are produced, the infected areas take on a white, powdery or dusty appearance fruit/rachis-pathogen appears as white, powdery masses that may colonize the entire berry surface. It can cause fruit cracking and promote molds
What are the symptoms of eutypa dieback?
causal organism: eutypa lata (and other diatrypaceae spp. *extensive infections lead to vine death symptoms: leaf and shoot - 2 years after infection -small chlorotic leaves with shortened internodes appear on stunted shoots -infected spur positions many flowers often dry before blooming, while many of the successfully fertilized flowers develop into small and sparse berries wood - 3 or 4 years after infection -darkened cankers that develop in the vascular tissue -cankers are often wedge shaped (like a pie chart) in cross-cuts of affected cordons or trunks foliar - 2 years after infection -stunted shoots with short internodes -leaves often cupped and with tattered margins - caused by translocations of toxins and fungal secondary metabolites (eutypa is not in the leaves)
What are the symptoms of verticillium wilt?
causal organism: fungus verticillium dahliae symptoms: -leaves begin to wilt and collapse in early summer heat, followed by death of some shoots, vascular discoloration, and streaking of wood -frequently, vines are only partially affected, and strong new growth often appears in unaffected portions -causes asymmetrical decline depending on the vascular tissue colonized minor disease *vines that are not killed can recover completely by the following year
What are the symptoms of phomopsis cane and leafspot?
causal organism: phomopsis viticola symptoms: -tiny dark spots with yellowish margins on leaf blades and veins -shoots: small spots with black centers similar to those found on leaves occur usually on a basal portion of the shoot -after spots lengthen a few millimeters, the epidermal layers of the shoots usually crack at the point of infection -heavy infection usually results in a scabby appearance of the basal portions of the shoot -clusters: spots similar to those that occur on shoots occur on the flower cluster stems
What are the symptoms of phytophthora crown and root rot?
causal organism: phytophtora spp. (oomycete) symptoms: - poor growth, stunting of shoots and leaves, rapid death of vine - crown and roots exhibit "wet" rot often dark chocolate brown - cause crown and roots to become dark brown/black as they die - tissue under the bark of infected crowns is killed and turns dark brown to black -do NOT form visible mycelium in or under host bark *only p. cinnamomi is pathogenic on grapes and only on certain rootstocks root and crown rot caused by p. cinnamomi has tended to occur in coastal valleys of California on fine- textured soils
What are the symptoms of downy mildew?
causal organism: plasmopara viticola symptoms: -most obvious symptoms are yellow oilspots on leaves that may or may not have "white-down" under the spots -"white-down" sporulation develop beneath the oilspots after suitably warm, humid nights -young berries: appear brown and oily, in warm humid weather, they may be covered with white downy growth
What are the symptoms of sour rot?
causal organisms: aspergillus spp., penicillium spp., cladosporium spp. symptoms: hairline cracks in the berry skin, watery discoloration of berries, and general berry breakdown
What are the symptoms of petri disease (young esca)?
causal organisms: phaeomoniella chlamydospora and phaeoacremonium spp. *root disease of newly planted vines that were at one time or another put under some kind of stress (early fruiting of the vines before year three, "J" rooting, and poor irrigation management or water deficit stress) -pathogens are common in soil and they occur as epiphytes on the exterior of grapevines -also endophytes (live in the water conducting tissue of grapevines) -if the vines are stressed, the pathogens appear to become more virulent and cause disease
What are the symptoms of esca?
causal organisms: phaeomoniella chlamydospora and phaeoacremonium spp. symptoms: leaf- display small, chlorotic intervenial areas that enlarge and dry out, red varieties dark red margins surround the dead interveinal areas, affected leaves may drop and canes may dieback from the tips, "tiger stripes" fruit- small, round, dark spots, each bordered by a brown-purple ring, may occur (measles), spots appear at any time between fruit set and ripening, severely affected vines the berries often crack and dry on the vine or are subject to spoilage vascular: "apoplexy" sudden vine collapse
What is the difference between crossing vs. hybridizing?
crossing: 2 vinifera parents hybridizing: 2 different species
What are the phomopsis cane and leafspot management practices?
cultural practices: -reducing the source of the disease is important -most of the inoculum for new infections comes from the spur and cane lesion, so infected cane/spur removal can be effective chemical treatments: -important in vineyards with a history of disease and in all areas spring foliar treatments are advised if rainfall is predicted after budbreak applications-> 1. before the first rain after budbreak 2. before 2 cm shoot length 3. again when shoots are 12 to 15 inches in length)
What are the sour rot management practices?
cultural: -management based on reducing injury or damage to the fruit, thus preventing invasion by bunch rot organisms -basal leaf removal at or after berry set has given excellent control of summer bunch rot in the San Joaquin Valley -warmer growing areas, be careful not to remove excessive numbers of leaves, which can lead to sunburned fruit -remove leaves only from the side of the vine that receives afternoon shade -leafhopper populations and damage caused by omnivorous leafroller have been reduced by this cultural practice chemical: -treat at pre-close and veraison if summer bunch rot has been a problem in the past
What are the armillaria root rot management practices?
cultural: only preventative -expose crown area and upper roots of vines to air -do not plant vineyards on oak studded hillsides chemical: fumigations -pre-plant chemical fumigation of the soil is the only control (no resistant rootstocks) -Sept-Nov when soil is dry -before fumigation with methyl bromide or sodium tetrathiocarbonate, dry out the soil as much as possible -drier the soil, the deeper the chemical will penetrate and the more effective the treatment will be -sodium tetrathiocarbanate is registered for control -alternative fumigant is a liquid that breaks down into carbon disulfide gas -applications 1 to 4 weeks before planting when soil moisture is at or near field capacity
What is integrated pest management?
ecological strategy focusing on long-term prevention through combination of: biological control, habitat manipulation, modification of cultural practices, use of more tolerant/resistant plant varieties
What is the amillaria mellea disease cycle?
facultative necrotroph colonizes living roots, kills root tissue and then utilizes the dead tissue as its source of nutrition (i) colonizes the cambium of living roots (parasitic phase) (ii) fungus kills the cambium, causing a necrotic lesion beneath the root bark (iii) fungus feeds on the dead tissue (saprophytic phase) -healthy plant roots can become infected when they come in contact with rhizomorphs from infected roots, preceding orchard crop, or nearby oak trees -favored by soil that is continually damp
What characteristics are in the eurasian species?
fruitfulness: good fruit quality: good usefulness: highly diverse products propagation capacity: good lime tolerance: good phylloxera tolerance: poor disease resistance: poor
What characteristics are in the american species?
fruitfulness: poor or highly variable fruit quality: poor usefulness: niche products propagation capacity: variable lime tolerance: highly variable phylloxera tolerance: good or variable disease resistance: good or variable
What is sclerotium/sclerotia?
hard, usually darkened and rounded mass of dormant hyphae with differentiated rind and medulla and thick, hard cell walls, which permit survival in adverse environment
What is meant by classical breeding?
hybridize or cross using selected parents
What is mycelium?
hypha or mass of hyphae that make up the body (thallus) of a fungus
What is the principle of breeding?
identify source of effective and durable genetic resistance, introgression into elite varieties (classical breeding), backcrosses to minimize the the genetic contribution of the non-elite parental
What is the plasmopara viticola disease cycle?
infection and reproduction requires free water 1. overwintering -pathogen survives the winter period as oospores embedded in dead leaves and other host tissue on the vineyard floor 2. primary infection -ospores typically produce macrosporangia -conditions necessary for oospore germination are wet soils with temperatures above 10C -sporangia produce zoospores -sporangia and zoospores are splashed by rain or carried by wind to the lower leaves and tissues of the grapevines -zoospores germinate and penetrate the host tissue causing the development of oilspots (quickest at 20-25C) 3. spread -new oospores are produced on the underside of oilspots ('white-down') during warm (>13C), wet (RH% > 98%) night -sporangia and zoospores are dispersed by water splashes
What is molecular breeding?
modern genetic tools optimize classical breeding
What are the phytophthora crown and root rot management practices?
no chemicals are recommended eradications is not feasible remove infected vines and remove soil keep graft union above soil line to minimize contact judicious irrigation can help control disease development (where pathogen is already present)
What are the sources of genetic resistance in grape vines?
non-vinifera grape species: muscadinia (rotundifolia), american vitis (riparia, berlandieri, lambrusca/concord)
What are downy mildew fungicides and how are they used?
preventative (prior to infection) - mancozeb, maneb, and copper compounds must be applied before an infection period begins, new growth following application will not be protected, include a spreader/sticker agent to prevent the material from washing off with rain, in vineyards with a history of downy mildew, apply early season copper sprays as part of a preventive program, especially during wet springs curative - strobilurin fungicides, phosphorous acids, copper fungicides, ridomil gold MZ and ridomil gold/copper
What are the downy mildew management practices?
preventative: -site and trellis system selection - effective soil drainage - reduction of sources of overwintering inoculum - in vineyard that depends on sprinkler irrigation, extend the interval between irrigations as long as possible
The impacts of pathogenesis can be avoided by?
reduce grape susceptibility, reduce inoculum potential of pathogen, manage plant environment (unfavorable conditions to pathogenesis)
What is meant by the term management techniques?
regulatory (quarantine, eradications, abatement), resistant cultivars (scion and rootstock breeding), cultural controls/management, biological controls, chemicals
What is genomic selection?
selection of multiple traits simultaneously
Diffrence between disease signs vs. disease symptoms?
sign: physical evidence of the pathogen (example: fungal fruiting bodies are a sign of disease) symptom: a visible effect of disease on the plant (example: canker or stunted growth)
What is the hypha?
single branch of mycelium or tubular filament of a fungus
What is the haustorium/haustoria?
specialized outgrowth (of mycelium) that penetrates a host plant and extracts nutrients
What are the symptoms of a powdery mildew early infection?
spring, ascospores are released during rains and sprinkler irrigation and are water splashed and windblown to newly emerging shoots and leaves individual colonies found on the lower surface of basal leaves are the first symptom colonies develop 6 to 7 days following a spring rainfall
What is meant by the term multiple resistant gene stacking?
stacking/combining multiple resistance genes to enhance resistance and reduce the likelihood of development of new virulent strains
What is the eutypa lata disease cycle?
storm with perithecia on dead trunk -> RAIN -> ascospores release -> WIND -> fresh pruning wounds -> several years after infection -> canker ->
What are the grapevine trunk diseases?
young (6-8 year old) vineyard -black foot -petri disease mature (8+ year old) vineyard -botryosphaeria dieback -esca -eutypa dieback -phomopsis dieback
