““Rehabbing Troubled Rehabbing Troubled Lawns”Lawns”

Rob Golembiewski, Ph.D.Rob Golembiewski, Ph.D.

OSU Oregon State University

Reasons for Turfgrass Failure

Improper cultural practices Drought, heat, or cold stresses Weeds, insects, or diseases Excessive thatch Unfavorable growth environment (shade,

poor soil conditions) General neglect, abuse, or overuse

Turf Improvement Programs

1.Initiate a program of sound cultural practices

2.Renovate turf by planting into existing live or dead vegetation

3.Totally reestablish the turf area

Assessment

Turfgrasses present Soil conditions (fertility, pH, and

drainage/aeration) Thatch levels Environmental conditions (light quanity,

quality, and duration) Existing perennial grassy weeds

Program 1 - Sound Cultural Practices

Turf has many acceptable characteristics, but in undesirable condition

Turf areas brought to acceptable quality by altering turf management practices

Successful Program

Existing turf must have: acceptable turf species/cultivar adequate density (potential for) acceptable soil conditions thatch level of ½” or less small number of perennial grassy weeds

Implementation

Integrate the following practices to bring turf into desired condition:mowingirrigationfertilizationcultivationpest control practices

0.5” 1.0” 1.5”

.5” 1.5”

0.5” 1.0” 2.0”

Unfertilized Balanced NPK + Fe

Balanced NPK

Program 2 – Partial Renovation

Often, poor turf requires more than improved cultural practices

Planting new seed into existing live or dead turf provides better turf appearance, density, disease/insect resistance, wear tolerance, and shade/drought tolerance

Successful Program

Should have proper: soil drainage/aeration pH fertility thatch levels less than ¾” small number of perennial grassy weeds if large number, apply nonselective

herbicide

Implementation

1a. Overseeding into live turf, mow short and remove debris to reduce canopy

competition for germinating seeds

1b. Overseeding into dead turf, use nonselective

herbicide to kill vegetation then mow to remove debris

Implementation

2. Open soil to enhance seed-soil contact via: hand raking vertical mowing core aerification slit seeding

3. If not slit seeding, broadcast seed

Vertical Mowing

1. Rotating blades physically extract thatch.

2. Blades should be set 1/8 to 1/4” soil depth.

3. Traverse area in at least 2 directions or until 30% of soil is exposed.

4. Seed applied by broadcasting or slit-seeding.

Core Cultivation

1. Hollow cylinder cones mechanically forced down into turf and soil plug is removed.

2. Removal of cores exposes soil which provides a mean for seed-soil contact.

3. Seed usually applied

by broadcasting.

Slit Seeding

1. Disk-like device slits the turf and seed is deposited.

2. Method most effective for obtaining good seed-soil contact.

3. Should be done minimally in 2 directions for effective coverage.

Broadcast Seeding

1. Not very successful method for good germination.

2. Spreading seed on a non-renovated turf results in little seed-soil contact.

Implementation

4. Incorporate seed with a drag mat or rake

5. Mulch

6. Irrigate daily until germination

complete

7. Mow once turf at intended height of cut

Program 3 – Complete Renovation

Sometimes turf so poor or the environment is unsuitable to support turf growth

Successful Program

This drastic method necessary when: soil conditions unsuitable to sustain turf

growth thatch levels greater than ¾” and

uncontrollable existing vegetation unacceptable and can’t

be improved

Implementation 1. Use a non-selective, short residual herbicide

like glyphosate (Roundup) or glufosinate (Finale) to kill existing turf and weeds

*Effectiveness of herbicides enhanced by: a. Skipping a mowing prior to treatment

b. Apply to actively growing turf

Implementation

2. Correct soil pH, drainage, and/or fertility problems by properly preparing the planting bed

3. Seeding or sodding can be initiated 3-5 days after treatment with non-selective herbicides

Post-Renovation Care

Once renovated turf has been seeded, turfshould be maintained as if it was a newly

established turf

Complete renovation: Kill/dethatch/reseed

Partial renovation: Dethatch/overseed

17 days after planting

Sod

SeedDethatched

SeedKilled/

dethatched

Summary

1. When turf unacceptable, determine reason for decline, select and implement program for upgrading turf

2. After turf improved, maintain sound turf management

program

Contact Information

Rob GolembiewskiOregon State University4017 ALS BuildingCorvallis, OR 97331

Phone: (541) 737-5449Email: golembir@hort.oregonstate.edu