PLP 266 Quiz #4

Melting Out pathogen

Drechslera poae

Smut Diseases pathogen

Ustilago sp.

Necrotic Ring Spot pathogen

Ophiosphaerella korrae

Dollar Spot pathogen

Clarireedia jacksonii

Leaf Spot pathogen

Bipolaris sorokiniana

Rust Disease pathogen

Puccinia sp.

Red Thread pathogen

Laetisaria fuciformis

Powdery Mildew pathogen

Erysiphe graminis

Ascochyta Leaf Blight pathogen

Ascochyta spp.

Slime Molds pathogen

Physarum cinereum

Ascochyta leaf blight turf species

• Kentucky Blue

• Perrenial Rye

• Fescues

Ascochyta leaf blight favorable conditions

Climate: 77 F

Conditions: Drought stress, too much N, excessive moisture

Season: Spring-Summer

Dollar Spot turf species

Most species

Dollar Spot Favorable conditions

Climate: Warm (59-86 F), humid weather, cool nights + heavy dew

Conditions: Severe on dry soil and low fertility

Season: Spring-Late Summer

Melting Out turf species

Kentucky Bluegrass

Melting Out favorable conditions

Climate: 38-58 F

Conditions: Thatch, excessive wetness, cool weather and shade

Season: Spring and Fall

Necrotic Ring Spot turf species

Primarily Kentucky Bluegrass

Necrotic Ring Spot favorable conditions

Climate: 65-80 F

Conditions: Hot, Dry and thatchy... first active in cool wet weather

Season: Visible in summer

Powdery Mildew turf species

Kentucky Bluegrass

Fescues

Powdery Mildew favorable conditions

Conditions: Slow growing conditions, poor air circulation, shade, excessive N, humidity, and high temps

Season: Late Spring, Late summer, early fall

Red thread turf species

Cool season grasses

Red thread favorable conditions

Climate: 60-90 F

Conditions: High humidity, cool, wet weather

Season: Spring-Fall

Rust Disease turf species

Kentucky Blue, Perennial Rye, Fescues, Zoysia

Rust Disease favorable conditions

Climate: 50-70 F

Conditions: Anything that subjects high HOC turf to stress or slows growth (shade, heat, etc.)

Season: Summer-Early Fall

Smut Disease turf species

Kentucky Bluegrass

Smut Disease favorable conditions

Climate: 50-68 F

Conditions: Dry soil, excessive N in summer,  stressed turf

Season: Spring and Fall

Ascochyta Leaf Blight symptoms

Large irregular patches, straw-like color.bleached tip to top third of foliage; needlelike leaf tips

Ascochyta Leaf Blight signs

Round black pycnidia (fruiting bodies) form in lesions or blighted tissue. Conidiaspores visible with hand lens

Ascochyta Leaf Blight cultural practices

Mow when dry at recommended HOC, water early and infrequently, avoid high N, use sharpened mower blades

Dollar Spot symptoms

On low cut turf, small irregular lesions that can
coalesce. On higher turf, small bleached patches... hour glass lesion on leaf blades

Dollar Spot signs

White, cottony, fluffy mycelium

Dollar Spot cultural practices

Rolling, remove dew, adequate N (avoid low N), control thatch, water lightly at night, avoid drought stress, Resistant cultivars

Melting Out symptoms

Varies by cultivar... Primarily a major disease for KBG... Small lesions form on leaves and spread down leaf/sheath and coalesce into larger spots... Eventually infects crown and can kill

Melting Out signs

None visible without microscope

Melting Out cultural practices

Spring N fertility, improve light exposure, raise HOC, remove thatch. Plant resistant varieties

Necrotic Ring Spot symptoms

Frog-eye, reddish blades in parts... similar in appearance to Summer patch only larger... creates depressions where turf has died

Necrotic Ring spot cultural practices

Limit N and light, daily irrigation, manage thatch

Powdery Mildew symptoms

Some minor yellowing of the blade

Powdery Mildew signs

Powdery white conidiospores

Powdery Mildew cultural practices

Reduce shade, improve air circulation

Red thread symptoms

Patchy, dull-green small patches with a faint pink hue

Red thread signs

Light-pink fungal stroma, cotton candy like arthoconidia

Red thread cultural practices

Reduced turf stress with adequate fertility and irrigation

Rust disease symptoms

Purplish-Orangish hue from a distance

Rust disease signs

Orange, powdery spores

Rust disease cultural practices

Reduce stress, increase fertility, raise HOC,
water early day

Smut disease symptoms

Initially, turf turns pale and growth stunts, narrow
streaks on leaf, leaf splitting

Smut disease signs

Blackish, grey fruiting bodies and spores

Smut disease cultural practices

When outbreaks are severe, fertilize only in fall, avoid excessive N in summer... water in droughty conditions, plant resistant variety

Soil Culture to Sand Culture and the problems that occurred

• Layering problems

• Nematode problems

• Localized dry spot problems

• Nutrient deficiencies

• Bacterial wilt

• Sulfur burns

• Black layer

Root rot nematode nematode

Cause: Meliodogyne arenaria

Occurrence: Wide temperature range

Grasses: Creeping bent, Bermuda

Short-term wetting agents

• Surf-Side 37A

• Primer

• Rely

• Fleet

Long-term wetting agents

• Cascade

• Brilliance

• Lesco Flow

Theories on the cause of black layer

• Algae

• Root dysfunction

• Soil mix

• Mismanagement

• Sulfate Reduction

Causes of anaerobic conditions

• Excess irrigation

• Heavy rains

• Traffic

• Sulfur

Fertilizer effect on turfgrass

Urea fertilizers- improved turf quality

Nitrate fertilizers- improved root growth

Black layer management

• Aerification

• Light irrigation

• NO₃ - fertilizers

• Oxyflow-H₂0₂

• Limit sulfur fertilizers

The Disease Triangle

1. Susceptible Host

2. Pathogen

3. Conducive Environment

Considerations for disease diagnosis

• Grass species

• Geographic location

• Time of year

• Soil type, pH, moisture, fertility

• Use/circumstances (golf, football, soccer, lawn)

• Mowing height/management

Major clues for disease

• Straight lines/patterns

• Physical damage

• Fungal signs

• Fungal symptoms