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54 Cards in this Set

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Powdery Mildew

Symptom: white powdery hyphae and spores on surface of leaves and flowers

Conditions: humidity, low air circulation

Control: fungicide (jojoba, neem), reduce humidity, destroy fallen leaves


Botrytis rot

Symptom: dehydration rot on grape clusters

Conditions: drought followed by high humidity

Control: air circulation


Brown patch

Symptom: circular, brown patches; fungus grows near crown, cutting off nutrient flow

Conditions: humidity, 85F+ Temp, affect cool season grasses, high nitrogen

Control: fungicide spray when nights are 70F+, 14 days


Dollar spot

Symptom: small, circular, white patches (close together make larger patches)

Conditions: warm daytime temps, cool/clear nights; low soil moisture and humidity on surface (dew or fog)

Control: fungicide


Summer patch

Symptom: root disease creates frog-eye brown patches affecting cool season grasses

Conditions: fungus affects roots and crowns in late spring; hot, direct sun or other stress factors in summer exacerbates problem

Control: lower pH; 5-10 (raise) mower height; balance fertilization


Fungicide: contols 14 turfgrass diseases and 50 ornamental diseases


Pink snow mold

Symptoms: round tan/gray/red patches 6-8", w/ pink tinge on margins during wet/cool weather

Conditions: cool temps and high moisture

Control: control nitrogen fertilizing;


Pythium blight

Symptoms: cottony growth grows particularly on rye and bent grasses

Conditions: high, 86-95F temps, high humidity, poorly drained soil,

Control: improve drainage; do not overwater


Anthracnose disease

Symptoms: sunken, ulcer-like lesions on stems, leaves, fruit or flowers (browning around leaf veins on sycamore; around margins on maple)

Conditions: cool temps; prolonged moisture

Control: clean up plant debris; fungicide


Dothistroma needle blight

Symptoms: deep green bands turn yellow/tan; needle drop, typically of older needles on lower branches; Austrian pine particular

Conditions: ?

Control: fungicide (copper); Bordeaux

Bordeaux mixture

a mixture of copper(II) sulfate (CuSO4) and slaked lime (Ca(OH)2) used as a fungicide to control downy mildew, powdery mildew, blights, etc


Sphaeropsis tip blight

Symptoms: young growth attacked, scales of young cones, excessive resin produced; dead needles at tips of branches held (Austrian and Scots pines)


Control: maintain health of tree (deep watering, fertilizing, etc); remove blighted shoots; fungicides (Bordeaux, Mancozeb)


fungicide control for blights


Brown spot

Symptoms: neddles develop yellow/tan, resin-soaked spots; needle drop (Scots and Ponderosa pine; Austrian pine resistant)


Control: fungicide (Bordeaux, Mancozeb)


Phomopsis tip blight of juniper

Symptoms: damage to new growth, foliar blighting, tip die back, small gray lesions girdle tips

Conditions: high humidity

Control: plant spacing for air circulation; water early hours; prune dead tips; avoid over fertilizing; fungicides (Mancozeb, Bordeaux)


Chestnut blight

Symptoms: grows through vascular cambium, girdling and killing

Conditions: invades wounds of cracks in the bark

Control: None (keep tree healthy/isolated)



Symptoms: diseased areas of leaf are irregular in shape and size (light green to yellow to brown) develop overnight Jun-Aug

Conditions: unknown (assoc. w/ dithiocarbamate fungicides

Control: ?



Symptoms: localized wound or necrotic lesion


Control: cut affected limbs (no chemical agents effective); prevention: fertilization, drainage, watering, selection


Apple Scab

Symptoms: localized lesions (raised, cracked scab-like) on fruit, leaves, etc.

Conditions: high humidity/rainfall in spring (incubate/accelerate germination/infection

Control: Fungicide benomyl (Benalte), chllorothalonil (Daconil, Bravo. Thalonil, Echo), coppers (Bordeaux, Kocide), etc


Cedar-apple rust (ala Hawthorn and Cedar Quince rust)

Symptoms: overwinter on junipers as galls, "telia" form in April producing spores which infect apple (or other Rosaceae) trees forming orange spots on leaves and "aecia" on underside, which spread back to junipers

Conditions: ?

Control: fungicide in spring on apple


Dutch elm disease (DED)

Symptoms: blockage of fungus causes discoloration of vascular tissue; wilting first in upper branches

Conditions: elm bark beetle vector; root grafting with nearby trees

Control: insecticide sanitation to reduce insects; fungicide


Early blight

Symptoms: spots on tomato leaves, infection spreads upwards, leaf drop,


Control: clean up debris; fungicide (Mancozeb, cholorothalonil, maneb)


Fusarium wilt

Symtoms: invades roots and affects oldest leaves and moves up; yellow to white to brown wilting of tomatoes

Conditions: cool soil; heat of summer; humdity

Control: 4-6 year crop rotation as it persists in soil


Verticillim wilt

Symptoms: invades roots and affects oldest leaves and moves up; yellow to white to brown wilting of 200+ species (strawberry and raspberry highly susceptible)

Conditions: cool soil; heat of summer; humidity

Control: 4-6 year crop rotation as it persists in soil


Black spot (roses)

Symptoms: localized lesion on upper leaf surface starting lower and moving up; (hybrid tea very susceptible)

Conditions: warm, moist weather

Control: good sunlight and air circulation to keep foliage dry; water from below; remove infected leaves; preventative fungicides


Mycosphaerella leaf spot (ash tree)

Symptoms: small, brown spots; early leaf drop;

Conditions: wet summers

Control: preventative fungicides


Root rot mold ([Christmas] Fraser fir tree)

Symptoms: deadening of leaves and limbs

Conditions: high moisture; poor drainage; standing water

Control: improve drainage


Clematis wilt

Symptoms: leaf spot fungus grows to stem causing cankers, wilting; purple veins

Conditions: poor air and soil circulation?

Control: good sunlight (6+hours); rich, well-drained coil; clean debris


Apple powdery mildew

Symptoms: distorted foliage; stunted twig growth; russetted/discolored/dwarfed fruit

Conditions: 90+% humidity; 50-77F temps

Control: good sun and air circulation; fungicide spray program


Powdery mildew of turf

Symptoms: powdery dusting on blades' upper surface causing withering and dieback

Conditions: shady sites, high humidity, ~65F temps; poor air circulation; Aug-Sep

Control: fertilize to get grass to outgrow disease; prune trees and shrub to improve light


Grape black rot

Symptoms: rot dramatically on berries which turn dark purple/black; berry shriveling (black rot mummies); brown rot on leaves with black lesions

Conditions: humidity?

Control: good air circulation; fungicides inhibit further infection


Brown rot of peach

Symptoms: affect blossoms (brown spots, turn black and die) have fungal growth which later infect twigs (stem cankers) and fruit (light brown spots grow);

Conditions: two infection periods: blossoming (temps 77F) and before harvest

Control: Sanitation is critical, debris clean up and fungicide


Ash rust

Symptoms: leaves and petioles distort; bright orange powdery cups which infects cord grass; cycles back next year

Conditions: wet springs;

Control: watering, mulching, fertilizing to increase tree vigor; prune infected areas; remove cord grass


peach leaf curl and plum pocket

Symptoms: leaves with thickened midrib with red/purple hue, die and fall; white spots on fruit enlarge, become seedless and enlargen


Control: new, uninfected leaves typically grow back, but spores in fruit keep cycle going each year; fungicide


Rhizosphaera needlecast on spruce tree

Symptoms: infects older, leaves on lower limbs turning needles purple/brown; late fall/next spring they fall off; does not kill, but severely affect the form of the tree

Conditions: low limbs infected by fruiting bodies which spread with rainfall

Control: fungicide (Bordeaux, Daconil, etc)


Root diseases of juniper

Symptoms: root rot

Conditions: presence of soil-born fungi with parasitic nematode, excessive watering and poor soil drainage

Control: plant in well-drained sites; fungicides/neamticides


Tip dieback of oak

Symptoms: wilting ("flagging") of black, cracked twigs or small branches throughout canopy; leaves bend backwards and turn brown (pin and red oaks)

Conditions: ?

Control: largely unnecessary as infection is minor; remove dead twigs

Bacteria: ERWINIA

Fire blight (apple, crabapple, pears, Rosaceae family)

Symptoms: infected leaves turn brown as if scorched;

Conditions: spring temps of 65+F; rain and pollinating insects;

Control: systemic antibiotics; program of several practices; prune; high nitrogen fertilizing

Bacteria: ERWINIA

Bacterial wilt

Symptoms: leaf wilt then plant wilts, browns and dies (cucumber and musk melon susceptible); test by cutting near crown; squeeze to see milky sap/fine threads

Conditions: cucumber beetle vector

Control: remove and destroy plant debris; insecticides


Bacterial spot of peach

Symptoms: affects fruit, leaves (pale green/yellow angular spots near leaf tip which fall off) and twigs (overwinters as cankers); (not extensive)

Conditions: rain and winds spread the bacteria from erupted cankers in spring

Control: proper fertilizer; hot/dry conditions inhibit


Pseudomonas blight

Symptoms: (on ornamentals, lilac, flowering (Bradford) pear, etc) enter through natural and wound openings and translocate to new growth, blackening new tissue

Conditions: cool, wet springs

Control: prune diseased limbs on warm, sunny day copper fungicide


Bacterial canker

Symptoms: (tomatoes) lesions and cankers anywhere; yellow wilting leaves become brittle and drop; fruit spots with white border halo

Conditions: wet, humid hot 80+F; spread by water/irrigation; infect wounds; carried systemically through plant

Control: use disease-free seed and soil


Pageant (R)

ornamental industry's foremost fungicide: effective on all four classes of fungicide

Fungus, Bateria, Virus effect:

Apple russetting

Symptoms: brown, corky, netlike condition on skin of fruit; cracking of fruit when severe

Conditions: environmental (heavy dew and cold temps during initial fruit development); chemical damage; excess nitrogen;

Control: ?


Seiridium canker of oriental arborvitae (also junipers and cypress)

Symptoms: formation of distinct, sunken lesions on bark, these cankers restrict water and nutrients leading to branch dieback and tree death; bleeding and resin formations in canker

Conditions: drought, winter damage, environmental stresses

Control: sufficient wateringer (esp in winter); prune out cankered limbs

Other: (mycoplasma-like [between bacteria and virus])

Aster yellow

Symptoms: green/yellow and twisted leaves (chlorosis, but has clear veins) and flowers; stunted, stiff, upright growth; blossoms deformed and sickly leaves

Conditions: spread by insect vector (aster leafhopper); cool, wet summers

Control: remove infected plants; insecticide


Corn smut

Symptoms: immature galls grow where spores land, white and spongy w/ greenish membrane, grow brown with powdery spores

Conditions: hot, dry weather; damaged plants

Control: remove infected plants before galls rupture


Iris leaf spot

Symptoms: small brown spots w/ water-soaked margins near leaf tip, enlarge w/ gray centers and may cause leaf death

Conditions: Rain in spring/growing season

Control: remove infected leaves; fungicide for severe conditions


Rose mosaic virus

Symptoms: ringspots, wavy lines, chlorotic vein banding, oak-leaf/mosaic/yellow net patterns symptoms show in late spring and endure all growing season; infection for life of plant

Conditions: transmission through vegetative propagation

Control: remove severely diseased plants


Rose rosette virus

Symptoms: rapid elongation of shoot; "witches' broom" cluster of small branches forms; excessive thorniness w/ red/purple pigmentation

Conditions: ? (transmitted possibly by eriophyid mite

Control: remove and destroy


Tomato spotted wilt virus

Symptoms: (tomato, pepper, other vegetables/ornamentals) inward cupping and off-color (bronzing) of leaves; tops appear yellow and wilting; white/yellow, half-inch rings on fruit

Conditions: ?

Control: remove and destroy; insecticides


Cucumber mosaic virus

Symptoms: (tomato, pepper, cucumber, melon, squash, spinach, celery, beet, petunia) distortion and mottling on older leaves (shoestring); stunted; reduced and mottled fruit

Conditions: infected aphids

Control: remove and destroy; insectidices


orange tomatoes

Symptoms: orange or yellow pigmentation

Conditions: temps above 95F; dry, hot winds; night temps above 75F

Control: harvest a bit early and store in 75-85F to develop red color


Blossom end-rot of tomato

Symptoms: small, water-soaked spot enlarges and darkens

Conditions: drought; lack of calcium

Control: plant in rich, well-drained, aerated soil; water as needed; mulching; fertilize (lower nitrogen; higher superphosphate)