Healthy Turf - Series 3 Article 3 - Combating Insect Pests

By Bobbie Herbs

Combating Insect Pests

Photo by PSU Estension

Integrated Pest Management

As defined by Penn State Extension, ‘integrated pest management (IPM) is a pest management system that is gaining popularity and acceptance in the turfgrass industry. It incorporates all suitable control techniques to keep pest damage below an established threshold level. The use of IPM strategies should result in effective pest control with minimal impact on the environment and on people. It is important to understand that IPM is not pesticide-free turfgrass management. However, a successful IPM program should result in a more efficient use of pesticides, which usually means a reduction in pesticide use.’ You can read more here: https://extension.psu.edu/developing-an-integrated-turfgrass-pest-management-program

There are several control measures that comprise IPM. They include:

• Cultural practices include mowing to the recommended height dependent upon the turf type you have, fertilizing based on soil tests, and proper watering techniques.  

•  Biological pest control methods use parasites, bacteria, fungi and other biological agents.

• Genetic controls include using pest-resistant species of grass.

• Controls must be specific to and target the pest. Alternating chemical controls aids in managing resistance which scientists and landscapers are discovering with more frequency.    

Identifying the damage-causing pest and understanding their lifecycle is essential to applying the correct, most effective treatments. In many instances, practicing healthy lawn care can mitigate infestations and damage.

Several insect pests can and should be treated in spring. For details on other insect pests requiring treatment in summer and fall Rutgers has provided a three-part series on specific insects, control measures and timing. You can search: Managing Turf Grass Insects of the Northeast Part 1, 2, 3.

Billbugs and Annual Bluegrass Weevil

Billbug, a surface-feeding insect, demands management in April or as the forsythia bloom ends.  Both billbugs and annual bluegrass weevil (ABW) infestations benefit from cultural and chemical controls. Although the signs of infestation may occur in summer, the optimal time for treatment is spring.  

Signs of turf infestation

Billbug

• Initially scattered dead stems, later growing patches of dead turf
• Damage in mid/late summer, especially during extended dry periods
• Symptoms often attributed to drought, dollar spot, brown patch, other insects.

ABW

• Small, yellowish-brown spots
• Scattered dead spots grow together
• Tunneled stems break off at crown
• Worst damage early to mid-June (1st generation)
• Usually less damage in late July/early August (2nd generation)

Cultural controls

Billbug

•  Endophyte-enhanced grasses more or less resistant to billbugs
• KY bluegrass varieties that are thinner leaved, aggressive creepers, and/or more heat/drought tolerant are more billbug-tolerant
• Moderate damage can be masked by light fertilization and deep watering

Chemical controls

Billbugs

• Preventive treatments vs. adults before egg-laying
•  spray or granules
• 1/10” post- treatment irrigation – withhold deep irrigation for 1-2 days
• Preventive treatment vs. young larvae inside plants using systemics
• Curative treatments vs. larvae in soil: spray or granules; 1⁄4” post-treatment irrigation
•  April – mid-July are the optimal times for chemical control use
• Refer to Rutgers University, Managing Turfgrass Part 3 for various pesticide use

ABW

• Preventative

-   short-residual insecticide vs. adults

-   systemics vs. young larvae inside plants

• Curative

-  Fast-acting insecticides vs. medium-sized to large larvae

-  Resistance to many insecticides has developed

-  Alternative insecticides for efficacy and avoiding additional resistance and use sound application practices

Chinch bugs

Chinch bugs have sucking mouth parts. They damage your lawn by sucking on grass blades. Interestingly, they secrete an anticoagulant that stops the grass from absorbing water therefore the grass withers and dies.  

Signs of Infestation

• Irregular patches of wilted, yellow-brown turf
• Coalesce into larger areas of dead turf
• Damage in hot, dry periods in July/Aug. in sunny lawns w/ thick thatch w/ south exposure
• Damage often masked by drought dormancy
• Warm, dry springs favor chinch bug buildup.    

Biological/Cultural Control

• Conserve natural enemies (selective insecticide use!)
• Beauveria bassiana can control chinch bugs under moist conditions
• Irrigate during dry periods to increase tolerance (also promotes Beauveria).
• Control thatch
• Over-seed / renovate with endophytic grasses

Chemical control

• Curative spot-treatments as needed
• Liquid or granular formulations

Cutworms

Cutworms are leaf & stem chewing pests. The ‘worm’ is actually the larval stage of a moth’s lifecycle. They shelter underground during the day and burrow out at night to feed on grass.  

Signs of Infestation

• Emerge at night to clip off grass
• Circular spots of dead grass or depressed spots resembling ball marks

Cultural controls

• Conserve Steinernema carpocapsae, this is a beneficial nematode that can also be purchased at retail

Chemical controls

• Use insecticides that address the larvae
• Apply late in day (feed at night)
• Don’t water in, delay mowing and deep irrigation for 1-2 days

A note on beneficial insects. There are plenty of insects that actually help control pests. They are often parasitic to pests, and at different stages of their lifecycle serve as food for birds and other fauna. Just like broadleaf herbicides can unintentionally kill your grass, chemical controls can kill beneficial insects. This is another reason to use chemical controls with caution and as a last resort.