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FOR IMMEDIATE RELEASE Jeannette Warnert
Almond leaf scorch taking a toll on San Joaquin Valley almond crops FRESNO – UC Cooperative Extension farm advisors invite San Joaquin Valley almond farmers to a Merced County orchard at 10 a.m. Monday, Oct. 20, to view examples of trees suffering from almond leaf scorch, a plant disease caused by the same bacterium that causes Pierce's disease in grapes. "Growers need to be able to recognize the symptoms of almond leaf scorch in their orchards early so that they can take precautionary measures against its spread," said Brent Holtz, Madera County UC Cooperative Extension farm advisor. The orchard viewing is on Orchard Drive between Gerard and Mission avenues in southeast Merced County. The orchard is wheelchair accessible and there is no charge. Holtz and Merced County UCCE farm advisor Maxwell Norton will point out the tell-tale symptoms of almond leaf scorch: a golden yellow band between a brown leaf tip and green leaf base. The yellow band sets the symptoms apart from salt burn and water stress, conditions for which almond leaf scorch is often confused. "The disease spreads relatively slowly and may not be noticed for several years," Holtz said. "If growers are aware of the disease and its symptoms, early infections can be removed by pruning." Almond leaf scorch has wreaked havoc on California almonds. In the 1950s it wiped out the almond industry in Lancaster, and in the 1970s it destroyed almonds growing in the Brentwood area. It has appeared sporadically in the San Joaquin Valley, but now farm advisors say the incidence is on the rise from Kern to Sacramento counties. California produces 99 percent of U.S. almonds, amounting to 700 million pounds in 2000 with a value of $680 million. Almond leaf scorch is caused by the bacterium Xylella fastidiosa, which is found in many common weeds and riparian plants, such as Bermuda, rye, fescue and water grasses, blackberry, elderberry, cocklebur and nettle without causing disease symptoms. The pests that most commonly spread the bacterium are spittlebugs and sharpshooter leafhoppers. In addition to Pierce's disease in grapes and almond leaf scorch, X. fastidiosa can cause alfalfa dwarf, phony peach disease, periwinkle wilt, citrus variegated chlorosis and leaf scorch of coffee, plum, pear, mulberry, elm, oak, sycamore, maple, oleander and pecan. For more information, contact Brent Holtz at (559) 675-7879, Ext. 209; or Maxwell Norton at (209) 385-7403. # # #
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