Mowing Yellow Starthistle An Alternative to Chemical Treatment

Mowing yellow starthistle at precisely the right time provides effective non-chemical control of the noxious weed, according to results of a demonstration project on Mariposa County rangeland by UC Cooperative Extension County Director Wain Johnson and UC IPM weed ecologist Tim Prather. Control is better with the herbicide Transline. However, even though its low rate of application costs just $12 per acre, the $365-per-gallon price is prohibitive for some small-acreage landowners. "They might want to consider mowing," Prather said. "But mowing at the wrong time may be worse than not mowing at all." The weeds must be mowed when three to five percent of the yellow starthistle flowers have bloomed. "Using this technique, we're not adding to the seed bank," Prather said. "Over a few years, the plants will decrease in population." If the weeds are mowed too early, they may flower again; if too late, the mowed seeds may already be mature. The scientists are also studying the introduction of forages and grasses to compete with yellow starthistle, with limited success. The absence of a heavy rain season, which may be in the offing for 1999, could favor this approach. For more information, contact Prather at (559)646-6534, prather@uckac.edu, or Johnson at (209)966-2417, cdmariposa@ucdavis.edu.

Dried-on-the-Vine Raisins Becoming More Popular

Following a frustrating 1998 raisin season, marked by labor shortages and weather woes, UC Davis viticulture specialist Pete Christensen believes drying raisins "on-the-vine" and harvesting mechanically will gain popularity. The key to the system's long-term success, he says, is new varieties. In contrast to the traditional production system, where grapes are cut off the vine and laid on paper trays to dry in the sun, dried-on-the-vine (DOV) systems have workers simply clipping the stem that connects the grapes to the plant. The grapes dry to raisins while still hanging in the canopy. On the vine, grapes take twice as long to dry, but are not harmed by autumn rains, which cause mold and imbedded sand on raisins lying on the vineyard floor. But most importantly, the raisins and paper trays need not be laboriously collected. Rather a harvester drives amidst the vines automatically gathering the fruit in bins. Now in commercial production on only 3,000 acres of the San Joaquin Valley's 175,000 acres planted to raisins, Christensen's confidence in the system's potential drives studies at the UC Kearney Ag Center on four trellis systems and a number of varieties. "The dominance of late-maturing Thompson seedless grapes in the Valley is a challenge to DOV development," Christensen said. Earlier maturing Zante Current, Fiesta and DOVine grapes show more promise for DOV production. For more information contact Christensen at (559)646-6552, christen@uckac.edu.

Jeannette Warnert
Public Information Representative
Ag and Natural Resources
UC Center
550 E. Shaw Avenue
Fresno, CA 93710