Developing a Management Plan for Reducing Thrips-induced Damage on Timothy Hay

Project Overview

Project Type: Graduate Student
Funds awarded in 2006: $10,000.00
Projected End Date: 12/31/2008
Grant Recipient: University of California, Davis
Region: Western
State: California
Graduate Student:
Principal Investigator:
Larry Godfrey
University of California, Davis
Principal Investigator:
Daniel Marcum
University of California

Annual Reports


  • Agronomic: general hay and forage crops, grass (misc. perennial), hay


  • Animal Production: feed/forage
  • Crop Production: application rate management
  • Education and Training: extension, on-farm/ranch research
  • Farm Business Management: budgets/cost and returns
  • Pest Management: biorational pesticides, chemical control, economic threshold, field monitoring/scouting, integrated pest management

    Proposal abstract:

    Timothy (Phleum pratense L.) is one of the most important and widely grown cool season grasses. There were 251,000 acres of cool season grasses grown in California in 2002. Timothy hay is a high-value commodity in the natural beef (fed only grains and grasses) and high-value horse feed markets. Thrips (Anaphothrips obscurus Müller) have recently been implicated in reducing hay quality by causing “brown leaf.” In California, the most effective registered insecticide is methidathion (Supracide 2E), but it carries a special needs label. Timothy treated with it carries the restriction of being fed only to horses. Producers who sell to other markets have been forced to rely on 4-6 organophosphate applications per year. In addition, potassium deficiency and plant density are suspected to augment brown leaf. Thrips monitoring procedures are minimal and vary widely. Integrated pest management (IPM) issues such as sampling, basic ecology, economic threshold levels, biological control, and others have not been studied in cool season grasses. Our research will focus on sampling protocol, treatment thresholds, and some overwintering ecology of this thrips in California. In addition, we will cooperate with local farm advisors and producers to explore cultural practices, nutrients, and varieties of timothy in California to establish an IPM program. This is part of a team effort involving cooperative research and extension personnel in California, the University of Nevada, Reno, and Washington State University. The goal of the project will be improving the economic and environmental benefits of growing timothy in a sustainable system.

    Project objectives from proposal:

    Producers need alternate management products and methods, as well as scientific sampling methods and treatment thresholds for control of thrips. We will develop sampling protocols for diagnostic evaluation of A. obscurus populations in timothy, correlating thrips numbers with damage, and studying some basic ecology of this pest. Moreover, we will reveal the causes of brown leaf by studying thrips, nutrient applications, and plant density, which will enhance grower knowledge. Finally, we will study alternate insecticide products for thrips control and timing of applications. This will lead to more precise nutrient and pesticide applications and sustainable growing practices for timothy, increasing profits for growers, while protecting the environment.

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.