Survey of Lettuce Downy Mildew to Identify Race and Fungicide Resistance

The Michelmore lab at the University of California, Davis routinely monitors isolates of Bremia lactucae, the pathogen that causes lettuce downy mildew for their ability to overcome disease resistance genes and for insensitivity to fungicides. In 2023 they characterized 96 samples from California lettuce growers and breeders. They welcome submission of additional samples and now samples can be dropped off at UCCE Monterey County in Salinas where they will be collected and shipped directly to the lab. Please see below for instructions on sending samples. 

Please fill in as completely as possible.  This will help entry into the database but do not worry if some of this information is not available. 

Please include this datasheet when sending isolates.

Date Collected: ____/____/_____                                                          (UC Lab ID: _________________)

Collector: __________________________________________________

Collector email or other contract info: ________________________­­­­­­­­­­­­­­­­­___________________________________  

Location: _____________________________________________________________________________________________

GPS coordinates if known: ____________________________

Disease Intensity / Level of infection (circle one):   

                        Low (Few infected plants),

                        Intermediate (Infected plants scattered throughout field). 

                        Severe (Many infected plants)

Please comment whether collected from a single plant or from several plants and whether from multiple locations in the field.

Comments: __________________________________________________________________________________________________________________________________________________________________________________________________________________

Fungicide treatment:  Yes     No       Not known

If yes: Alliete          Ridomil          Orondis               Other:__________________

Type:   Crisphead       Romaine      Looseleaf       Butterhead       Babyleaf     Other:______________

            Cultivar/Variety: ____________________________________________________________________________

            Approximate planting/water date ________________________________________________________

Other Comments: _________________________________________________________________________________________________________

Thank you for your help.  Please address questions to Charlotte Acharya (cacharya@ucdavis.edu), and/or Richard Michelmore, rwmichelmore@ucdavis.edu.  

Results will be available from https://bremia.ucdavis.edu/bremia_database_main.php.

Collection and Shipping Instructions:

Drop-off in Salinas:

• University of California Cooperative Extension (1432 Abbott Street, Salinas CA 93901)
• For sample drop-off, open Monday through Thursday, 8:00 a.m. through 4:00 p.m. Closed daily 12:00 to 1:00 p.m. Closed weekends and holidays.
• Contact Yu-Chen Wang with Salinas drop-off questions, yckwang@ucanr.edu or 831-201-9689

Or ship directly to lab:

Please send overnight by Fed Ex (Account # 2630-4693-5) in a box rather than an envelope (to prevent samples being crushed) along with the datasheet and the words “Refrigerate upon arrival” on the outermost packaging to:

Attn: Charlotte Acharya

The Genome Center

Genome and Biomedical Sciences Facility

451 East Health Sciences Drive

University of California

Davis, CA 95616

Tel. 607-227-3471

Please notify Charlotte Acharya (cacharya@ucdavis.edu) with the tracking number when sent.

Please time the sending so that the isolate is not in the Fed Ex system over a weekend (i.e. do not send on a Friday).  Isolates can be kept in a fridge at 5^oC for a few days before sending if necessary, although sending samples immediately after collection is best.