November 20, 2013

Many Topics Discussed in Salinas

By Patrick Cavanaugh, Editor

Steve Koike
Steve Koike, UC Cooperative Extension Farm Advisor, plant pathologist, opened up University of California Cooperative Extension—Monterey County 2013 Plant Disease Seminar talking about new soil born diseases affecting strawberries.

Koike said the new soil born disease problems surfaced in 2006 in Ventura and Orange Counties where they stopped using the traditional Methyl Bromide/Chloropicrin fumigation application. That’s when the problems arose, such as Charcoal Rot, or Macrophomina, as well as Fusarium.
Koike noted that Macropomina and Fusarium are bad news for the industry because they are so damaging to strawberries, easily spread from field to field and may be a long-term challenge. There are no truly resistant strawberry cultivars, alternate fumigants are not completely effective, bed fumigations are insufficient and post-plant fungicides do not work.

Breeders are trying to produce cultivars with resistance to these diseases.

Krishna Subbarao
Krishna Subbarao, a UC Davis Plant Pathologist reported that Verticillium wilt is spreading throughout Monterey County. It was discovered in 1995 on lettuce in the Watsonville area and made its way to Salinas Valley 6 years later, and eventually to Kings City.

Plant Disease Crowd
Infestation has reached new highs, new areas, and with increased losses. Subbarao and his team are trying both to identify all the different species of Verticillium through DNA testing and to breed Verticillium resistance into lettuce cultivars.

Trevor Suslow, UC Extension Research Specialist with statewide responsibilities in food quality and safety, spoke about emerging produce safety issues regarding human parasites and viruses.

New equipment at UC Davis can help eliminate false positives of pathogenic toxigenic E. Coli possibly eliminate a recall on products.

Trevor Suslow and Drew Mather
On the subject of Listeria, Suslow reported that the more likely point of entry for Listeria is the processing and handling environment and not really the product. It is seen in product tested after its use-by date, as Listeria has the ability of to grow in refrigerated storage over long periods of time.

Research has shown that Listeria numbers fall off very quickly, 32 days, after a field is inoculated.

Alec Gerry
Alec Gerry, Associate Professor and Extension Specialist UC Riverside discussed protecting leafy greens from contamination with Filth Flies, also known as bottle, blow or garbage flies.

Filth flies carry E. Coli from a manure source such as a dairy into a lush field of lettuce and contaminate the crop. Desiring sugar (carbohydrates), the insect seeks to find it in a field where honeydew secretion has been left by other insects.

Gerry suggested growers plant a tree line barrier, place stinking bottle traps on the fence line, improve fly attraction with better odors and develop screens to deter, catch or kill the Filth flies.

Tatiana Simkova and Steve Klosterman
Steve Klosterman, USDA Research Molecular Biologist, spoke about the spinach’s primary disease, Downy Mildew (DM). Fungicides effectively control DM in conventional fields; organic growers rely on resistant varieties, but the breeders may not be able to keep up.

Klosterman’s lab is working on specific detection and quantification of DM. Knowing what DM races are present may prevent spraying, thus avoiding resistance.

For extended coverage on this meeting, see upcoming issues of Vegetables West Magazine.