Screening for non-host rotation crops of Colletotrichum acutatum for strawberry nurseries in California

Project Overview

Project Type: Graduate Student
Funds awarded in 2008: $19,535.00
Projected End Date: 12/31/2009
Grant Recipient: University of California, Davis
Region: Western
State: California
Graduate Student:
Principal Investigator:
W. Douglas Gubler
University of California, Davis

Annual Reports


  • Agronomic: barley, corn, flax, millet, oats, potatoes, rapeseed, rye, sunflower, wheat, grass (misc. perennial), hay
  • Fruits: berries (other), berries (strawberries)
  • Vegetables: asparagus, beans, beets, broccoli, carrots, cauliflower, garlic, onions, peas (culinary), peppers, sweet corn, tomatoes
  • Additional Plants: herbs, native plants, ornamentals


  • Animal Production: feed/forage
  • Crop Production: cover crops, fallow
  • Farm Business Management: whole farm planning
  • Pest Management: compost extracts, cultural control, integrated pest management, prevention, trap crops
  • Sustainable Communities: sustainability measures

    Proposal abstract:

    California is the major state for strawberry production in the U.S., and accounts for over 80% of the fresh market product grown in this country. California strawberries are also an important component of international production, growing over 20% of the world’s strawberry supply. Strawberry is among the most challenging horticultural crops to grow due to a variety of pest issues that growers must manage. Colletotrichum acutatum is representative of a large group of opportunistic fungal pathogens that affect a wide range of crops such as strawberry, blueberry, almond, avocado, peach, citrus, mango, and olive. The pathogen is able to infect most parts of the strawberry plant from roots and crown to leaves, fruits, and flowers. Most economic losses are suffered when the fruit is infected; however plant collapse, resulting when planting stock is infected, has also been a severe problem for strawberry growers in California. Crop rotation has been shown to be a sustainable farming practice that can result in both increased levels of organic material, as well as lowering the general pathogen populations in soil. California strawberry nurseries prefer to be on a several year rotation between strawberry plantings. The problem is that we do not know if the cover crops that are being planted are a host of Colletotrichum acutatum. Our greenhouse tests, through isolation, have shown the ability of Colletotrichum acutatum to survive and infect rotation crops. It is unclear whether the pathogen is able to sporulate and thereby increase inoculum levels, or whether it produces overwintering structures on various host tissues. Studies are needed to determine the importance of rotation crops in producing inoculum, thereby increasing pathogen survival and providing a source of inoculum for adjacent planting fields. Reduction of inoculum density by preventing pathogen propagation in the rotation fields through the use of non-host crop plants would be an ideal and sustainable way to suppress C. acutatum. Screening for non-host rotation crops is a feasible and an important approach to provide growers with science-based practices that warrant disease-free rotation fields and a high quality of planting stocks.

    Project objectives from proposal:

    1. Determine whether or not the commonly used cover crops are a host for C. acutatum or, if not a primary host, determine what role they may play in the survival of this fungus during the rotation period.

    2. Screen crops that have possible inhibitory effects on the germination and growth of C. acutatum. Evaluate their potential as novel rotation crops.

    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.