Management of Cut Flowers & Ornamentals

James Gerik Project Leader
USDA-ARS Water Management Research Unit and San Joaquin Valley Agricultural Sciences Center, Parlier, CA

Collaborating Team Members:  Husein Ajwa, UC Davis; Mona Othman, UC Davis; Sadikshya Dangi, U. C. Davis; Susanne Klose, UC Davis.

Methyl bromide alternatives for cut flower and ornamental bulb production

Cut flowers, bulb and ornamental crops are a highly productive and valued component of California’s agriculture. In 2008, California growers produced cut flower crops with a wholesale value of more than 314 million dollars.  In the past, shank injected methyl bromide/chloropicrin (MB/PIC) combinations of 67:33 and 98:2 were the dominant soil disinfestations practice in cut flower and ornamental crops because of their ability to diffuse rapidly through the soil and effective and consistent control of a wide range of pathogens, nematodes, weeds, bulbs and seeds.

Because of the broad-spectrum pest control provided by this fumigant combination, hundreds of species and thousands of varieties of flowers can be grown on relatively few acres. Soil fumigated with MB/Pic generally can be planted in just a few days after removal of plastic covers.  Currently, only three MB alternative fumigants are commercially available for cut flower field production, and intensive research is being conducted to optimize application technologies to improve their performance and reduce application costs. Registered chemical alternatives are Pic, 1,3-dichloropropene, and methyl isothiocyanate generators such as metam sodium and metam potassium.   Although most alternative fumigants can be applied to the soil by shank injection, new technologies were developed to apply fumigants through drip irrigation systems. Drip and shank applied alternative fumigants for cut flowers and ornamental crops have been evaluated over the past few years.  Although these alternatives have shown potential to replace MB in some cut flower and bulb crops produced in the open field, the feasibility of their use in greenhouses using drip irrigation under gas-tight film and in the open field for each of the major species of ornamentals grown in California remains to be demonstrated, and none of these materials are currently registered for use in greenhouses.