From the UC Blogosphere...
By Leonard Cicerello UCCE Master Gardener
Why are my Cypress dying in my front yard? Joe B. Paso Robles
A study published in 2011 by UC Berkeley and Italian researchers may have solved a decades-long mystery behind the source of a tree-killing fungus that affected six of the world's seven continents. The pathogen, Seiridium cardinale, also known as Cypress Disease or Cypress Canker, was likely introduced from California either in the south of France or in central Italy 60 to 80 years ago. Its introduction devastated the region's iconic Italian cypress trees. Researchers found historical catalogues of large commercial nurseries in Italy and France and found records of mature Monterey cypress trees for sale during the late 1920s and 1930s. The records indicated significant imports of the California trees and their seeds during that time.
Seiridium cardinale was first identified in California's San Joaquin Valley in 1928. The fungus attacks trees in the cypress family by entering through cracks in their bark and producing toxins that wreak havoc with the flow of sap, limiting the supply of water and nutrients. The cracks in the bark could be caused by pruning cuts, boring insects, or weather damage. The spores spread by wind and water splash. Symptoms include dieback beginning from the top of the tree or branches browning and dying throughout the canopy. A branch can change color over a period of days.
You may see thin, elongated cankers on the stems and branches. These cankers cause twig and branch dieback. Most cankers are wounds, slightly sunken, with raised margins, and they may be discolored, dark brown to purple. An infected tree with cracked bark often has extensive resin that flows down the diseased branches and trunk. Once most of the canopy has turned brown, that limb or tree will almost certainly die. The whole limb or tree should be removed and properly disposed of.
The principal hosts for cypress canker are Monterey cypress, Italian cypress, Leyland cypress, Lusitania cypress, and Arizona cypress. It is best not to replant new cypress immediately following the removal of diseased trees. No specific cure exists. The best you can do is supply adequate water, minimize soil compaction, apply a thin layer of mulch, and avoid wounding the tree.
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UC Cooperative Extension is asking California farmers and landowners to help track the the state's wild pig population, reported Julia Mitric on Capitol Public Radio News. Signs of the pig's presence are hard to miss, UCCE advisor John Harper told the reporter.
"It looks like you came in with a rototiller and just uprooted everything," he says. "It's like ground squirrel mounds or gopher mounds on steroids because the pigs can go over such a large area."
California's wild pigs have a variety of origins. Harper says many are descended from domestic pigs who were released into the wild by humans or escaped on their own and bred with game hogs such as the Russian boar hog. Wild pigs root around in the soil for truffles and small plant roots with their sharp tusks tear, destroying plants and grasses that sheep and cattle like to graze on. They also open up the land for erosion and invasive species.
"So you might get something like 'medusahead,' an invasive grass that tends to crowd out other more desirable forage species," Harper said.
A team of UC Cooperative Extension scientists have created a GIS-based mobile app that works on Android and Apple devices to make it easy for landowners to participate in the study.
“Rangeland managers and farmers can enter data into the app from the field so that we can estimate the land area and economic impacts of feral pig damage over a longer time period,” said Roger Baldwin, UC Cooperative Extension wildlife specialist in the Department of Wildlife, Fish, and Conservation Biology at UC Davis.
Learn more and sign up to participate in the study on the UC Agriculture and Natural Resources news website.
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