UC Gardening Blogs
Pollinator Habitat: Important Part of Solar Energy Study
Solar energy should not only be used to benefit global sustainability, but to protect our global...
Solar energy can be used to protect pollinator habitat, according to a research paper published July 9 in the journal Nature. This is Anthophora urbana, a ground-nesting solitary bee which has a broad distribution including the Mojave Desert. It is a floral generalist collecting pollen and nectar from many species of plants, says UC Davis entomologist Leslie Saul-Gershenz. (Photo by Leslie Saul-Gershenz)
Native bee Megachile sp. on Mentzelia flower in the Mojave Desert. (Photo by Leslie Saul-Gershenz)
Fire blight (Erwinia amylovora)
When I first inherited this pear tree it was hemmed in between two structures and restricted to a 3-foot diameter opening in the concrete. I had noticed that several of the branches growing straight up were blacken and appeared dead. I assumed that the recent drought had caused the problem. No problem I said to myself. I repeated the dead, dying or diseased tree mantra and remove the branches. I cut the branches and thought problem solved and that was that. Since then, one of the buildings has been removed as well as all the concrete. The tree has done better and produced a number of pears. When it was hemmed in it only had a few inedible pears.
Later that year Sally Thompson a classmate in my Master Gardeners Class said what are you going to do with that fire blight on your pear tree. She continued, “I know what fire blight looks like I have it on several ornamental pears growing next to my house.” Really fire blight? I realized that she was right after all she's a Master Gardener. I did a little research and confirmed her diagnosis. It was more than just dealing with dead wood but a serious disease that could be transmitted throughout the entire tree, maybe killing it and even spread to my newly acquire apple trees.
Fire blight is named because of the appearance of the limbs, leaves and fruit look like they got hit and blacken with a blow torch. It's caused by a bacterium, Erwinia amylovora, and there is no cure for it, but control and prevention are possible.
At the outset choosing the right tree is Important. According to the UC IPM article on Fire Blight, certain varieties are susceptible: Asian Pear (except Shinko) and red pear varieties are just a few. An ornamental pear tree to avoid is the Aristocrat. Fire blight can also infect other pome fruit trees such as several apple varieties: Fuji, Gaia, Golden Delicious. Granny Smith, Jonathan, Mutsu, Pink Lady, and Yellow Newton are more susceptible than other apple varieties. The disease starts in the flowers so trees that bloom late in the spring or throughout the seasons can have severe fire blight damage. In my case, however, I had to deal with the tree I inherited or cut it down entirely.
Even though I pruned the damaged limbs from the tree, it was still infected. E.amylovaora winters over in cankers and in twigs and branches and even the trunk of diseased trees. You have to wait for the symptoms of the disease to appear before you can do preventive maintenance. I had removed several infected limbs last year using a 10% bleach solution between the cuts. You should cut at least -12” below the infected area. Check for discoloration at the cut, the inside of the cut should show clean heartwood with a definite dark layer of bark. Just below the bark, there is a layer of cambium. This is living tissue of the tree and where E. amylovora invades. The cambium should be distinct and be uniform all around if there is some discoloration and or irregular growth in one area you may have to cut further back.
But this summer I noticed more infected twigs and branches with the disease. I got out my pruning shears dipped them in bleach and disposed of the twigs branches and leaves into the Green Recycling bin. Never put the infected tree parts in the compost, you'll just spread it around even more effectively than the wind or rain could ever do. The best time to prune the tree is after the spring growth and when there is less moisture in the air. Summer or late Fall would be the best times for pruning.
Over-fertilization is another no-no. The bacterium takes advantage of new growth from the additional nitrogen in the soil and spreads rapidly.
Weather is an important factor in the spread of fire blight temperatures between 75 – 85 F daytime with 55 F at night accompanied by rain are ideal conditions for disease spread. If those conditions exist, be on the lookout for signs of infestation. The disease spreads from the flowers to the shoots invading the cambium a thin layer just below the bark.
I probably will be fighting fire blight on my pear tree as long as it lives. It has survived many years with the disease so it probably won't die soon. Without management, the situation may become worse. My other concern is keeping the disease in check because I don't want it to spread to the new pome apple trees I have planted. Because the disease is not systematic on my tree, I am just pruning as needed and disposing of the infected limbs and leaves in the green waste. Hopefully and this will work and I will have several years of fruitful rewards.
There are chemical (liquid copper) and biological management (organic sprays) tools available. Check with the UC IPM (Integrated Pest Management) Program for the latest and safe use of pest control products for fire blight.
Fire blight blasted end of branch. (photos by Brenda Altman)
fireblight brenda altman 2019
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Here's Why Your Workplace Needs a Water Balloon Battle
The posters displayed at the Bruce Hammock Alumni Lab Reunion last August in the UC Davis...
This is researcher Christophe Morisseau's water balloon battle poster, now on display in the Briggs Hall basement, outside his office. (Photo by Kathy Keatley Garvey)
Water warrior Bruce Hammock gets doused. (Photo by Kathy Keatley Garvey)
Research posters at the Bruce Hammock Alumni Lab Reunion were mostly scientific--except for several fun ones, including a water balloon battle poster. (Photo by Kathy Keatley Garvey)
Researcher Christophe Morisseau (right) of the Hammock lab shows photos of previous water balloon battles to two colleagues. In the center is Kin Sing Stephen Lee of Michigan State University, an alumnus of the Hammock lab, and Bruce Graham Hammock (son of Distinguished Professor Bruce Dupree Hammock) of the UC Davis School of Veterinary Medicine. (Photo by Kathy Keatley Garvey)
Cindy McReynolds (left) of the Bruce Hammock lab talks about her scientfic poster at the Bruce Hammock Alumni Lab Reunion, held last August at the UC Davis Conference Center. (Photo by Kathy Keatley Garvey)
Fun at the lab reunion: Karen Wagner, Hammock lab alumnus, takes a selfie with Jim Sanborn, retired from UC Davis; researcher Christophe Morisseau of the Hammock lab, and Kin Sing Stephen Lee of Michigan State University, an alumnus of the Hammock lab. (Photo by Kathy Keatley Garvey)
Ugni Molinae
In early June on the way home from a trip to Bodega Bay, my husband and I stopped in at the Luther Burbank Gold Ridge Experiment Farm. Luther Burbank, the famous American plantsman, had purchased the farm in 1885 and used it as a base for his long successful career. He is credited with developing over 800 varieties of plants, the most famous probably being the Santa Rosa Plum and the Shasta Daisy. The site has a self-guided tour and a nursery! If volunteers are not present, there is an honor system for purchasing plants. The address is 7777 Bodega Avenue, Sebastopol, CA.
One treasure we discovered at the farm is Ugni Molinae also known as strawberry myrtle or Chilean guava. According to the Plants for a Future website, this plant is native to Chile and southern Argentina. It has wonderful, small, fragrant flowers and berries, that are described as smelling and tasting like wild strawberries. It is used in making jams, desserts and a liqueur called murtado.
This plant is in the Myrtle family and can grow in USDA zones 7-11. It can get as tall as 6 feet and 3 feet wide and can be used as an ornamental hedge. It tolerates most soils as long as they are well drained. It prefers sun and can tolerate wind. It has both male and female flowers on the same plant and thus is self-fertile, but is pollinated by bees. Established plants are reported to be drought tolerant.
Another intriguing fact about this plant is that it was introduced to Britain in 1844. Queen Victoria was said to have adored its berries made into a jam. Apparently, she really liked eating, and this was one of her favorite foods.
Ugni molinae
Water Warriors Bracing for Bruce Hammock Lab Water Balloon Battle
They're baking in France. The village of Villevieille recorded an historical high temperature of...
Undergraduate biological sciences major Andrew Kisin of the Aldrin Gomes lab, UC Davis Department of Neurbiology, PHysiology and Behavior, tosses a container of water at Bruce Hammock, UC Davis distinguished professor. (Photo by Kathy Keatley Garvey)
In this 2017 photo, Bruce Hammock douses Louisa Lol, who served as his executive administrative assistant before moving to Michigan. Her husband, Kin Sing Stephen Lee, formerly of the Hammock lab, is on the faculty of Michigan State University's Pharmacology and Toxicology. She serves as an administrative assistant at the university. (Photo by Kathy Keatley Garvey)
In this 2012 photo, Hammock lab researcher Christophe Morisseau chases a fellow water warrior, postdoctoral scholar Pingxi Xu of the Walter Leal lab. (Photo by Kathy Keatley Garvey)
In this 2018 photo, "splash brothers" Bruce Hammock (left) and Christophe Morisseau go at it. (Photo by Kathy Keatley Garvey)