News Stories

. . inside the November-December issue of California Agriculture:

Since recombinant DNA techniques were first developed by University of California, San Francisco, and Stanford University scientists in 1973, biotechnology has found commercial application in medicine, food processing and, more recently, agriculture. This year U.S. growers planted 45 million acres of transgenic crops, including herbicide-tolerant, insect- and disease-resistant varieties. But while transgenic crops offer new options for California farmers, they raise questions as well. This issue of California Agriculture explores two of them: how privatization of proprietary rights to key biotechnology will affect public germplasm development, and how the problems of pest resistance may affect the long-term success of larvae-killing transgenic cotton.

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 entities. At the same time, a series of mergers and acquisitions in the agrochemical and seed industries has led to increasing dominance by a small number of 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. These changes present problems both for growers of major crops, who find they have an increasingly limited number of suppliers, and growers of minor crops, who may find that transgenic research useful to them is never developed because the potential market is too small.

Plants genetically engineered to produce insecticidal proteins of the bacterium Bacillus thuringiensis provide effective, environmentally safe pest control. However, current transgenic crops have in some cases encountered insect resistance, partly because they have been engineered to produce only a single type of Bt insecticidal protein, and partly because as crop plants age they may produce lower amounts of the Bt protein.

Minor failures have occurred over the past three growing seasons. In Texas, corn earworms with high tolerance to the Bt toxin Cry1Ac invaded some fields of Bt-cotton, virtually destroying the crop. In Australia, the principal cotton pests are bollworms, which are also quite tolerant to this toxin. This year the Bt-cotton held off the bollworms for only half the season, then growers had to apply pesticides to control them.

Sparkling pear wine could provide alternative market for pears. UC scientists have found a use for blemished pears that cannot be packed for fresh market or canned. The scientists suggest that making pear cider could greatly improve the demand for pears and enable vintners to make use of wineries during the off-season. Their experiments demonstrate that an ultrapremium-quality cider can be made from ripe Bartlett pears.

The cost of producing pear still wine (before secondary fermentation adds the bubbles) by custom crush is $275 per ton of pears. The cost of finishing the cider varies with the approach. Making a beer-like beverage was the least expensive. The classic sparkling wine mŽthod champenoise, involving a secondary fermentation in the bottle as in champagne making, was the most expensive, but yielded the highest quality beverage. Bottling and packaging the value-added product also varied. 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.

Early season release of Willamette mites confers plant resistance. Wine grapes serve as hosts for several species of mites. Field trials in the Central Valley revealed that some mite management practices were far more successful than others. For instance, miticide and insecticide treatments led to resurgences of mite populations to damaging levels. Releases of predaceous mites provided inconsistent control of leaf-chewing mites. However, releases of Willamette mites at low densities early in the growing season consistently reduced high populations of Pacific mites throughout the season. Willamette mites can become pests, but 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 the fecundity and survival of Pacific mites.