- Author: Tunyalee Martin
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 could 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.
- Author: Ben Faber
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- Author: Joey Mayorquin, Mohamed Nouris, Akif Eskalen and Florent Trouillas
Figure 1: Citrus shoot dieback (top) and gummosis (bottom) caused by Colletrotrichum. |
A new disease of citrus has been found in the main growing regions of the Central Valley of California. The causal agents of this disease were identified as species of Colletotrichum, which are well-known pathogens of citrus and other crops causing anthracnose diseases. Several growers and nurserymen in various orchards in the Central Valley first noticed the disease in 2013. Symptoms include leaf chlorosis, crown thinning, gumming on twigs and shoots dieback, and in severe cases, death of young trees. The most characteristic symptoms of this disease are the gum pockets, which appear on young shoots either alone or in clusters and the dieback of twigs and shoots (Fig.1). Field observations indicate that symptoms initially appear during the early summer months and continue to express until the early fall. These symptoms were primarily reported from clementine, mandarin, and navel orange varieties. In order to determine the main cause of this disease, field surveys were conducted in several orchards throughout the Central Valley. Isolations from symptomatic plant samples frequently yielded Colletotrichum species. Morphological and molecular phylogenetic studies allowed the identification of two distinct species of Colletotrichum (Colletotrichum karstii and Colletotrichum gloeosporioides) associated with twig and shoot dieback. Interestingly, these Colletotrichum species were also isolated from cankers in larger branches. Although C. gloeosporioides is known to cause anthracnose on citrus, a post-harvest disease causing fruit decay, it has not been reported to cause shoot dieback of citrus. C. karstii however has not been reported previously from citrus in California and our research team is currently conducting field and green house studies to determine the pathogenicity of this species in citrus. At present, it is unclear how widespread this disease is in California orchards or how many citrus varieties are susceptible to this disease. Pest control advisors are monitoring citrus trees for the presence of the disease in the Central Valley (particularly clementine, mandarin, and navel varieties) during the early summer months. Continuing research led by Dr. Akif Eskalen in collaboration with Dr. Florent Trouillas is focused on further understanding the biology of the fungal pathogens as well as factors influencing disease expression in order to develop management strategies against this emerging disease.
- Author: Tunnyalee Martin and Cheryl Wilen
Sometimes an invasive pest takes a while to become invasive. The Invasive Species Council of California defines an invasive species as “non-native organisms which cause economic or environmental harm.” So, until a species not originally from the area actually causes harm, it doesn't get the title of invasive.
Take the Italian white snail, also known as the white garden snail. In San Diego, it caused extensive damage to agricultural plants in the early 1900s but was considered eradicated after a massive control program in the 1920s. However, it was found again in San Diego County in the 1980s but it did not damage agricultural crops or gardens. Instead the snails lived off of weeds in neglected fields. Now it appears to be moving slowly from these fields to fruit tree orchards and avocado groves as well as landscapes. The Italian white snail feeds on decaying organic matter and living plants, damaging leaves, flowers, and fruit. Another fear is it being found in cut flower growing areas or in nurseries where it could become an export issue.
White or light tan, the Italian white snail is about the size of a dime or nickel when fully grown. It may or may not have brown markings on the outside of the shell. The inside shell color near the opening is light colored (compared to the milk snail, which looks similar but has a dark inside shell). Italian white snails are most noticeable during the day and when it is hot, because the snails climb up on fence posts, walls, weeds and other vegetation and congregate in large numbers.
In California, the Italian white snail is only officially found in San Diego County. However, it could easily move to new areas because of its small size, which makes it hard to detect, and tendency to attach to many kinds of surfaces such as truck beds. Also, because land snails are hermaphroditic—each snail has both male and female reproductive organs—it only takes any two snails to reproduce!
Californians can help in the fight against invasive species by learning and participating during California Invasive Species Action Week, June 2–10.
- Author: Ben Faber
The Irrigation Training & Research Center (ITRC) of Cal Poly San Luis Obispo tested 28 different pressure-compensating models of microirrigation emitting devices from a total of nine manufacturers in order to compare independent laboratory testing with manufacturer specifications.
The test results indicate that:
The majority of ~0.5 gallon-per-hour emitters (drippers), regardless of manufacturer exhibited:
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Good uniformity of manufacturer
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Had excellent response to pressure variation
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Had consistent flow rates within the nominal operating pressure range
But that the percentage of well-performing products decreased as the designed flow rate increased. Many of the emitters designated as microsprinklers or sprayers, although pressure compensating did not compensate at the normal operating pressures. Often the pressure compensating feature did not start performing until much higher pressures were achieved. Often this occurred when clogging occurred and this clogging often occurred where the pressure diaphragm was located and was not performing. Sediment would get in back of the diaphragm. Effectively the emitters were not pressure compensating. The testing procedure of numerous medium and high flow models also found individual pieces were found to be defective. These faulty emitters had a measurable effect on the evaluation for those models.
Read more at: http://www.itrc.org/reports/pdf/emitters.pdf
An example of the comparisons that ITRC canbee seen here of their results, compared to the manufacturers' values: