All Issues

Over the next 7 years, all agricultural uses of methyl bromide (MBr) will be phased out, in compliance with mandates from the US. Environmental Protection Agency and the UN Environment Programmed. This compound has been widely applied as a soil fumigant, and its loss will be felt throughout the state, though more in some crops and regions than in others. Research shows that the heaviest economic loss will be sustained by strawberry growers in the Central and South Coast regions and by nursery operations statewide. A phase-out beginning with the low-value uses of MBr would avert some of the inefficiencies implied by canceling all agricultural uses at once.

The economic impacts of methyl bromide's (MBr) phaseout for postharvest fumigation vary widely among growers and, in the case of fumigation to meet quarantine restrictions, may vary widely from year to year. For walnuts, if processors use an alternative pest control strategy with a longer treatment time, a smaller supply of walnuts will be ready on November 7, a target date for shipping to Europe for the holidays. Cancellation of MBr could effectively eliminate access to export markets for cherries, peaches and nectarines until alternative quarantine treatments are approved by trade officials.

Since the 1950s growers have routinely used soil fumigants such as methyl bromide (MBr) and 1,3-dichloropropene (1,3-D) before replanting orchards and vineyards. Fumigants double plant growth in the early years after replanting and provide several years of nematode relief when resistant rootstocks are unavailable. However, the recent suspension of 1,3-D and the mandated phase-out of methyl bromide by 2001 have clouded the future of fumigant use. To develop alternatives, we must first document the pest control value and plant growth benefit of fumigation. Over the last decade, we have initiated several 2-year field trials in replant sites in the San Joaquin Valley. Our results quantify fumigation benefits and point to the feasibility of some alternatives, including a portable soil drencher.

Southern California growers raise artichokes from seed as annuals for a winter harvest to take advantage of the favorable winter market prices. However, this method of production ties up fields for 9 months because the plants mature at different times. Now trials have revealed that multiple applications of gibberellic acid produce an earlier and more uniform first harvest in annual artichokes.

Cutting off irrigation two weeks before harvest substantially reduced the damage caused by hull rot in a Kern County almond orchard trial. The extent of leaf death was affected by the stage of hull split at which the fruit were inoculated, but not by the concentration of inoculum.

Screens can exclude certain pests from greenhouses and therefore reduce the need for pesticides on greenhouse crops. They can perhaps also be used to create a small production area for biological control organisms within the greenhouse. When selecting a screen for either use, the pore size in the material is an important factor.