Diagnosing Summer Turf Problems

• Webinar for State Hotline/Diagnostic team

• Kevin Frank, Ph.D

Associate Professor

MSU Plant, Soil, and Microbial Science

Hosted by Consumer Horticulture Staff

Bob Bricault & Mary Wilson

Diagnosing Summer Turf Problems

• Environmental

• Cultural

• Insect

• Disease

Environmental

Drought stress symptoms • Bluish green to bluish grey

• Advanced stage is straw colored

• Foot prints persist

• Cultural options

• Increase mowing height

• Check for root feeding insects

• Check for compacted soil

• Dormant grass – when is water necessary to save plants

Heat Tracking

Cultural Induced Stress

•Mowing too short

•Dull mower blade -End of blades shredded

Dull Mower Blade

Cultural Induced Stress

•Mowing too short

•Dull mower blade -End of blades shredded

•Thatch layer is more than ½ inch thick

-Compacted soils, Poor drainage, Over fertilization

Lawn Insects

Japanese Beetle Grubs

• Root feeding

European Chafer Grubs • Root feeding

Sod Webworm • Surface feeding

Common Lawn Insects

Sod webworm

Photo courtesy of the University of Purdue

Chewing damage on edge of grass blades. Areas where grass blades are missing and small green fecal particles present. Small caterpillar found in silken tubes in thatch

Sod Webworm

• Larvae overwinter and resume feeding in the spring

• 2 generations per year

• Dirty white moths may be observed flying across turf at dusk

• Mowing may “kick up” adults

Spring damage

Larva and frass

Adult bluegrass

webworm

Sod Webworms

Summer Turf Diseases

Necrotic Ring Spot

• Yellow patches up to 2 feet often with green patch in center

• Common on compacted, poorly draining turf

• Excess nitrogen can increase problem

Summer Turf Diseases

Necrotic Ring Spot Management

• Resistant cultivars

• Aeration/increase mowing height/irrigate/organic or slow release nitrogen

http://www.msuturfdiseases.net/details/_/necrotic_ring_spot_13/

Summer Turf Diseases

Summer leaf spot • Irregular patches • Yellow to tan lesions with reddish brown margins • Severe at high temperatures and high N conditions

• Management • Alleviate thatch and any compaction • Moderate fertility • Minimize leaf wetness • Raise mowing height

• http://www.msuturfdiseases.net/details/_/leaf_spot_7/

Summer Turf Diseases

Rusts

• Orange to red pustules on blades

• Orange spores gets on shoes

• Management

• Maintain fertility

• Irrigate to prevent drought/ minimize leaf wetness

• Tolerant cultivars

Photo by D. Settle

Summer Turf Diseases

Dollar spot • Bleached lesions with red to brown

margins

• Warm days, prolonged leaf wetness

• Stressed from low nitrogen and dry soils

• Management • Reduce thatch and compaction

• Use tolerant cultivars

• Maintain fertility

• Avoid drought stress

• Minimize leaf wetness

Photo: Eric B. Nelson, Cornell University

Diagnosing Turf Problems

Resources:

MSU Turf Disease

• http://www.msuturfdiseases.net/

MSU Diagnostic Lab

• http://www.pestid.msu.edu/

MSU Turfgrass Science

• http://www.turf.msu.edu/home-lawn-articles