- Author: Richard Smith
- Author: Steven T. Koike
Clubroot disease can be a serious production issue for broccoli, cauliflower, and other brassicas in the Salinas Valley. The disease is caused by a unique organism (Plasmodiophora brassicae) that is closely related to ciliate protozoans but is classified in its own taxonomic group. It survives over 20 years as resting spores in the soil that are released as the clubbed root tissue decays. At temperatures above 65 °F, the resting spores release zoospores that swim to host plant roots and infect through root hairs. Once inside the plant, the organism grows into a large multinucleate plasmodium (a multinucleate mass of protoplasm) which stimulates changes in the plant hormones, resulting in enlarged root cells and...
- Author: Richard Smith
- Author: Michael D Cahn
During the past two years acreage of season-long drip in lettuce has increased rapidly in the Salinas and adjacent valleys. Using drip for the entire crop cycle allows growers to germinate seeded crops with buried tape (Photo 1), and eliminates labor needed for installing and removing sprinklers. The rapid expansion of this irrigation practice is due to 1) reliable thin-walled single-use drip tape which assures high application uniformity for less cost than thick walled tape; 2) Better injection equipment that can uniformly place drip tape 2-3 inches below the soil surface allowing cultivation without damaging the tape (Photo 2), and 3) development of tape removal equipment that saves labor and efficiently bundles the tape for...
- Author: Richard Smith
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 PCA's 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: Richard Smith
Onions is a challenging crop in which to achieve good weed control. They are planted in high density configurations that preclude the effective use of cultivation. Cultural practices such as locating plantings in fields have low weed populations, as well as preirrigating up a flush of weeds followed by killing them with shallow cultivation can be effective in minimizing the population of weeds that emerge during the crop cycle.
In general, excellent weed control for many of the common cool and warm season vegetables can be accomplished by a combination of the registered pre- and post-emergence herbicides. The weed control challenges in onions occur with weeds that are not well controlled by currently registered herbicides. It is...
