The garden symphylan is an increasingly common problem on organic farms. Symphylans have a diverse diet, feeding on decaying organic matter and on the roots of a very wide range of crops and other plants, including many weeds. Heavy symphylan populations can severely stunt, and even kill, most annual
crops. To our knowledge, there are no organically acceptable symphylan control strategies that have been shown to work consistently and most of the information about organic control strategies for symphylans is anecdotal and often contradictory.
We conducted field and laboratory studies at the Davis and Santa Cruz campuses of the University of California to evaluate a number of symphylan management and control strategies and to develop and evaluate methods for studying symphylans and their management. In field studies we evaluated the effects of a number of cover crop and cash crop residue treatments, shrimp shell extracts and tillage effects on symphylan populations over time. In laboratory trials, we evaluated modifications of soil pH,
a number of neem formulations, the commercial product Farewell, mustard seed extracts and three species of predatory nematodes for their effects on symphylans.
The results of our field studies did not indicate any simple practice or material that reduced symphylan populations by an agronomically significant amount. However, based upon our work and that of others, growers may be able to utilize information about the biology and behavior of symphylans to better manage fields with damaging symphylan populations. Knowledge of symphylan sampling methods, symphylans' vertical migrations in the soil and potential impacts of cultural practices such as tillage and irrigation may help growers use symphylan infested fields productively.
Our laboratory studies indicated some materials had a biological effect on symphylans under laboratory conditions, but how such materials could be used effectively to reduce symphylan populations under field conditions was not demonstrated. These materials are strong candidates for further study in the laboratory and field.
Information dissemination and exchange has been an integral part of this project. We have discussed this project with growers, consultants and researchers from the initial stages of our work and relied on them to help guide and focus our activities. Articles about our work have been written for the UCSC Cultivar and the CCOF Statewide Newsletter and we expect at least one more article in a grower-oriented
publication. We also conducted a farmer-researcher workshop that focused exclusively on organic symphylan management at the 2001 Ecological Farming Conference. The purpose of this workshop was to share and exchange information and ideas with approximately 50 growers and other participants and to help refine future research and extension goals and objectives.
This project had three objectives:
Objective 1. To determine the effect of different management strategies on established populations of Scutigerella immaculata in replicated field trials at the UC Davis Student Experimental Farm and the UC Santa Cruz Center for Agroecology and Sustainable Food Systems farms, based on results of preliminary work done at these and other sites.
Objective 2. To continue to develop effective symphylan rearing media and techniques for the amplification of stock populations to use in bench trials as an essential first step in studying the efficacy of potential biological control agents.
Objective 3. To disseminate information about the results of these studies and other practical information about organic symphylan management to the organic farming community.