Posts Tagged: California

Summer—it’s a time for swimming, BBQs, camping, and eating invasive species.

Last week during California Invasive Species Action Week (June 2 – June 10), we highlighted several pests, but there are many more invasive species out there. Now that you know about them, share your knowledge of invasive species with others. And no matter what your summer plans, here are some things YOU can do about invasive species from the California Department of Fish and Wildlife and California Department of Food and Agriculture.

YOU:  I'M TRAVELLING TO AMAZING PLACES

• Learn what plants and animals you can bring into California.
• Don't pack a pest! Declare all food and agricultural items from other states or countries.
• Find out which species are threats to California.
• Learn about California's invasive plants.
• Avoid spreading forest pests: buy your firewood where you burn it.

YOU:  I'LL BE WORKING IN MY GARDEN

• Remove invasive plants from your property.
• Select native or non-invasive plants for your garden.
• Use only certified weed-free forage, hay, seed, mulch, soil, and gravel.
• Learn alternatives to releasing unwanted fish, aquatic plants, and other pets.
• Monitor plants and trees for symptoms of infestations and disease.
• Learn about California's invasive plants.
• Have you spotted an invasive species? Tell us where by reporting your sighting.

YOU:  I'LL BE NEAR THE WATER OR ON A BOAT

• Join the statewide citizen science effort to monitor for quagga mussels.
• Join the iNaturalist project, California Nerodia Watch, and help us find Nerodia watersnakes.
• Make sure to Clean, Drain, and Dry (PDF) your boat after each outing.
• Learn alternatives to releasing unwanted fish, aquatic plants, and other pets.
• Visit your favorite local, state, or national park, ecological reserve, recreational area, or nature center and ask about their volunteer programs.
• Learn about California's invasive plants.
• Have you spotted an invasive species? Tell us where by reporting your sighting.

YOU:  I'LL BE OUT AND ABOUT CAMPING, HIKING, OR RIDING HORSES

• Use only certified weed-free forage, hay, seed, mulch, soil, and gravel.
• Avoid spreading forest pests: buy your firewood where you burn it.
• Prevent the spread of plant pathogens that damage and kill California's native plants and trees.
• Learn about California's invasive plants.
• Visit your favorite local, state, or national park, ecological reserve, recreational area, or nature center and ask about their volunteer programs.
• Have you spotted an invasive species? Tell us where by reporting your sighting.

YOU:  I'LL DEFINITELY CONTINUE TO LEARN ABOUT INVASIVES

• Get to know your local invaders.
• Learn about California's invasive plants.
• Find out which species are threats to California.
• Learn alternatives to releasing unwanted fish, aquatic plants, and other pets.
• Eat them. Yum. Check out these websites to find out who is edible and how to prepare them.

• Invasive-eats.com (California-specific)
• Invasivore.org (under construction but hopefully back soon)
• EatTheWeeds.com
• EatTheInvaders.org

If you missed it this year, help in the fight next year by learning and participating during California Invasive Species Action Week.

If you've got a great recipe for wild fennel, the website Eat the Invaders wants to know. Wild fennel is listed as moderately invasive by the California Invasive Plant Council (CAL-IPC). It came from southern Europe and the Mediterranean where it is used as a spice. (Photo: Joseph M. DiTomaso, UC Davis Dept. of Plant Sciences)

If you've got a great recipe for invasive brown garden snail, the website Eat the Inbaders wants to know. Don't bring snails and other animals into California for food! That's how the brown garden snail ended up here in the 1850's. (Photo: Jack Kelly Clark, UC IPM)

Bacterial canker and blast damage appearing.

Prunes are just past petal fall, but I've been shown several examples of bacterial canker and/or blast in the last week (see pictures below). 

These symptoms are caused by infections of Pseudomonas syringae pv. syringe, a common bacteria found throughout orchards.  Particularly in years with cold wet winters/springs, the bacteria enter prune trees -- and other stone fruit and almonds -- damaging scaffolds (bacterial canker) and buds (bacterial blast).  The bacterial blast generally is not a major economic issue for growers.  However, canker can spread rapidly and kill trees from the top down.  Strangely enough, the rootstock is not affected by the bacteria, and damaged trees often show vigorous sucker growth.   

Once the symptoms appear, there is little to be done.  Don't remove damaged trees when symptoms first show.  The trees may recover.

Bacterial canker is associated with:

• Soil related stress such as acid soils, shallow soils over hardpan, or coarse texture (sandy) soils with nematode (specifically ring nematode) pressure.  The bacteria don’t enter the plant through the soil – at least they don’t harm the rootstock, but soil stresses predispose the tree to above ground infection.
• Low soil nitrogen availability
• Pruning during wet, cool weather.
• Rootstock selection.  M2624 is most sensitive to bacterial canker, although M29C is susceptible as well.  M40 is reported to be the rootstock that is least susceptible to bacterial canker.

What can be done to avoid bacterial canker?

• Avoid soil stresses listed above, wherever possible.
• Spot fumigate to control nematodes in coarse texture (sandy) soils
• Maintain adequate soil nitrogen levels
• Prune in late summer/early fall  or late spring
• Plant on M40 rootstock

Also, Jack Dibble, retired UCCE entomology specialist, told me that, in his experience, trees with bacterial canker pressure showed dormant oil burn more readily than trees not under pressure from bacterial canker.  If your block is at risk from bacterial canker (sandy soils, low N levels, nematodes, etc.), consider avoiding high dormant oil rates.

Prune trees showing bacterial canker symptoms (scaffold collapse, gumming).  Sutter Co.  April 8, 2011

 Prune buds damaged by bacterial blast.