Calag Archive

This year, U.S. growers planted 45 million acres of genetically engineered crops, primarily corn, soybeans, cotton and potatoes (Pollan 1998). These transgenic “smart crops” can produce their own insecticides, or withstand broad-spectrum herbicides such as Roundup or Liberty. Some say these developments signal the coming of age of the most profound technological revolution since the advent of computer technology. But while transgenic crops promise new options for California farmers, they raise questions as well. For instance, a series of laws, legal judgments and Patent Office decisions during the last two decades have transformed property rights and incentives in the seed industry. Today genetic materials ranging from DNA sequences to whole plants, as well as essential biotechnology tools and techniques, are being patented by private and public research entitles. At the same time, a series of mergers and acquisitions in the agrochemical and seed industries have led to increasing dominance by a small number of transnational corporations in these fields. Such industrywide changes signal a profound shift in the ownership of life forms and the recombinant DNA tools needed to manipulate them. How will the existing options for assigning “ownership” change the way in which germplasm development will occur? How will those changes affect farmers?

More than 10 million acres of transgenic insect-resistant crops, including cotton, corn and potatoes, were planted in the United States in 1998 — and growers are on the verge of much more extensive plantings. Genetically engineered to produce insecticidal proteins of the bacterium Bacillus thuringiensis, these plants provide effective, environmentally safe pest control. However, current transgenic crops may lead to insect resistance, partly because they have been engineered to produce only single Bt insecticidal proteins, and partly because plant senescence can result in lower production of Bt proteins as crop plants age. Australia cotton growers, for instance, found they had good control for the first half of the season in 1997, but required insecticide treatments in the latter half. Resistance avoidance strategies and crop varieties in the pipeline that produce two or more insecticidal proteins are planned to provide long-term resistance management. This is crucial not only to growers using the transformed crops, but to organic growers who rely on traditional Bt insecticides. If successful, this new technology promises high crop yields as well as benefits to most nontarget arthropods and biological control insects by reducing the use of broad-spectrum chemical insecticides.

Wine grapes in the Central Valley serve as hosts for several species of mites. Because these species have radically different economic effects, their correct identification is essential. Field trials revealed that some management practices were far more successful than others. For instance, treatments with dicofol (a miticide) and car-baryl (for leafhoppers) produced resurgences of mite populations to damaging levels. Releases of predaceous mites provided inconsistent control of herbivorous mites, and cover crops did not provide any clear advantages for mite management, although they may have other benefits. However, releases of Willamette mites at low densities early in the growing season consistently reduced chronically high populations of Pacific mites throughout the season. (Willamette mites, though they can become pests, are not damaging at low densities.) Scientists do not fully understand how Willamette mite releases confer plant protection, but evidence suggests they stimulate the host plant to reduce fecundity and survival of Pacific mites. Manipulations of host plant resistance offer new possibilities for control of pests such as spider mites.

The effectiveness of resident insect predators as biological control agents of peach twig borer was tested in a series of field experiments. Results showed that the native gray ant was the most common and effective generalist predator. Treatments with native gray ant present had significantly lower peach twig borer abundance and peach shoot damage. Ant population densities were studied in seven commercial orchards. Results showed that although this ant is found in most peach and nectarine orchards, its abundance was not clearly associated with any single cultural practice and may be difficult to manipulate.

Pear growers and packers continue to need profitable market channels for fruit that is not packed for fresh market or canned. Off-grade fruit that is designated for the juicing market frequently gives growers and packers poor returns unless there are significant shortages of fruit juice concentrates in the marketplace. Finding a use for these fruit in the creation of a higher priced, value-added premium product could greatly strengthen the performance of this segment of the pear market and at the same time use the off-season production capacity of sparkling wineries. Our experiments demonstrate that an ultrapremium-quality cider can be made from juice grade Bartlett pears. Pear fruit should be ripe for optimum flavors and aromas.

Commercial production of pear cider could greatly improve the demand for pears that are not packed for fresh market or canned. Bringing pear cider, also called perry, to the marketplace will involve careful planning and market knowledge. The cost of producing pear still wine by custom crush is $275 per ton of pears. The cost of finishing the cider varies with the approach. The classic sparkling wine method champenoise, involving a secondary fermentation in the bottle, was the most expensive, but yielded the highest-quality beverage. Bottling and packaging the value-added product also varied in price. The retail costs would be $3 for a 22-ounce bottle of pear cider and $6 for a 750-milliliter bottle of sparkling pear wine.