General Comments

Dr. Parrella has retired from UC Davis as of January 2016.  Themes from his research program have continued in studies conducted by the Nansen Lab Group in the Department of Entomology and Nematology.

The Parrella Laboratory Group focuses on developing and implementing IPM strategies with an emphasis on biological control for the Environmental Horticulture industry.  This includes floriculture, nursery and bedding production operations and landscape plants in the urban environment.  Major pests including western flower thrips, silverleaf and greenhouse whiteflies, Liriomyza leafminers, green peach and melon aphids, psyllids, and spider mites.

There are unique aspects associated with developing IPM programs for aesthetic value crops and these must always be taken into consideration if programs are to be eventually adopted by the industry. We focus on understanding the relationship of the pest to the crop (including its unique production practices), to the environment and to its natural enemies.  Simply stated, investigating the basic biology and ecology of a pest at the individual and population level is the core of the program.

Status and Needs of the Industry and Research Outreach Directions

Cash income generated by the production of nursery, greenhouse and floriculture crops in California exceeded more than $3.795 billion in 2006, accounting for more than 11% of total agricultural production in the state (USDA 2007).   This was the second leading agricultural commodity in California, exceeded only by milk and cream ($4.492 billion).  Although the value of agricultural crops in California dropped 4% from 2005-2006, the value of nursery, greenhouse and floriculture crops actually increased by 0.5%. Examining data from the California Department of Pesticide Regulation reveals the following amounts of pesticide active ingredient were applied by the environmental horticulture industry in 2005: Landscape maintenance = 1,751,475 lbs; greenhouse floriculture = 51,820 lbs; greenhouse nursery crops in containers = 60,599 lbs;  greenhouse transplants = 10,361 lbs; nursery outdoor plants in containers = 1,292,942 lbs; nursery outdoor floriculture = 338,785 lbs; and nursery outdoor transplants = 981,621 lbs.  When taken in total, the environmental horticulture industry applied  4,493,603 lbs of pesticide active ingredient in 2005.   While this is much less than many of our major agricultural commodities in California, this statistic for environmental horticulture would be ranked much higher if pounds of pesticides per acre rather than total pesticides used was the measurement variable.  We have already seen that the adoption of IPM and biological control by these growers will reduce the amount of pesticides used and will improve detection of exotic pests and reduce the spread of biotypes resistant to one or more pesticides.

While inroads have been made, there is still a long way to go.   In particular, there is a real need to reduce pesticide use in the landscape, and in outdoor nursery floriculture and container grown plants.