- Author: Elizabeth Mosqueda
- Author: Richard Smith
- Author: Steven Fennimore
- Posted by: Gale Perez
Elizabeth Mosqueda is an Assistant Professor at the California State University, Monterey Bay.
Richard Smith is a Vegetable Crop Production and Weed Science Farm Advisor with UC Cooperative Extension.
Steve Fennimore is a Cooperative Extension Weed...
- Author: Nelly Guerra
- Author: Steven Fennimore
Despite the tremendous need, there are currently no preemergence herbicides that are organic-compliant. Steam injected into the soil such that the soil temperatures reach >140°F for 15-20 minutes will kill weed seed in the soil. The effect of this reduction in the seedbank viability results weed control in the treated area that persists for several weeks or months, similar to the effects of a preemergence herbicide.
Two studies were conducted at the USDA Hartnell Farm at Salinas, CA during July to September 2020. Steam was applied to raised beds using a custom-built steam injector. Prior to seeding lettuce, steam was applied in a 4-inch wide band to a depth of 3 inches deep. The steam was supplied by a SF-20 Sioux steam...
- Author: Richard Smith
- Posted by: Gale Perez
Richard Smith is the Vegetable Crops and Weed Science Farm Advisor in Monterey County, California.
Impatiens Necrotic Spot Virus (INSV) in the Salinas Valley is a tospovirus that is spread primarily by western flower thrips (Frankliniella occidentalis). It has a wide host range of over 600 species of plants, including vegetables such as lettuce, tomatoes and peppers, ornamental such as fuchsias, dahlias and gazanias, and many weeds (see below). In the summer months when INSV is well established, lettuce production fields serve as the primary host of the virus, and thrips fly from infected fields that are being harvested to younger unharvested fields, and in that way, propagate and spread...
- Author: Richard Smith
- Posted by: Gale Perez
Weed control in lettuce and other crops is a key issue this time of year. Purslane is particularly problematic and is adapted to warm conditions and can grow very rapidly especially during July and August. At times growers and PCAs are disappointed with the efficacy of Kerb on this weed. Kerb is effective in controlling purslane but it is readily leached and, if applied at planting, it can be moved below the zone of germinating weed seeds with the germination water. For instance, 6-8 hours of sprinkler water (1.5 to 2.0 inches) are commonly applied in the first germination water which can move the Kerb below the upper 0.5 inch of soil which is the zone where the weed seeds germinate; the movement of Kerb with the germination water is...
- Author: Oleg Daugovish
- Posted by: Gale Perez
Over the years of Kerb use in lettuce (more like decades) there has been a lot of work on application methods. Our transplanted lettuce in southern California is usually grown on drip and when possible, we like to apply all things through it. Our fields are surrounded by four cities and folks there just don't seem to enjoy sprayer rigs that much.
At the UC Hansen Research & Extension Center (clay loam soil) we applied Kerb at 2.5 and 5 pints/A rate either via drip or bed spray. The herbicide was applied with second irrigation after transplanting of ‘Inferno' romaine (great name for green lettuce). The irrigation continued after Kerb application to assure moisture movement from drip tape past the plant...