- Author: Annemiek Schilder
In this weekly blog, Dr. Annemiek Schilder, Director, UCCE Ventura County and Hansen Agricultural Research and Extension Center, shares her observations about the natural world across the seasons. As she says:
"Gently observing your surroundings with curiosity will teach you some amazing things. There are so many fascinating things happening under our noses, only wanting for an observant eye."
"What is wrong with my peach tree?"
Many people have probably asked this question as they have stared in concerned wonder at the distorted leaves of their peach trees. From a distance the striking color patterns may even look like peculiar flowers. Peach leaf curl is a disease of peach and nectarine trees caused by the fungus Taphrina deformans, an apt name for this fungus. Ornamental peach trees, grown for their beautiful blooms, are also susceptible to this disease.
Peach leaf curl is a common plant disease featured in many plant pathology textbooks. It may well have been the disease that convinced me to become a plant pathologist (a plant doctor) as I peered with increasing fascination at its structures under the microscope.
Allow me to digress a little to discuss that great invention: the microscope. In the late 1600's, Antonie van Leeuwenhoek, a self-taught Dutch scientist, developed a single lens microscope with up to 300 times magnification, allowing observation of bacteria for the first time. He called them “little animals”. However, it would take another 200 years before bacteria and fungi were officially recognized as causes of disease in animals and plants, laying the groundwork for modern-day medicine.
The name of this disease, peach leaf curl, is quite descriptive as the fungus causes leaves to curl and develop blister-like areas. Rainy, cool springs promote infection - as well as spore production - on infected leaves. Spores are spread by wind and rainsplash to other leaves, where they can cause new infections. The disease is not only unsightly –except to the eyes of a plant pathologist, of course - but also causes diseased leaves to drop prematurely, which weakens the tree and may lower fruit yield. In severe cases, repeated defoliations can kill a tree.
Taphrina deformans spores are produced in elongated structures called asci, a Latin word meaning “sacs”.
Have you noticed that Latin is used a lot for botanical descriptions? This is because Latin is a “dead” language and thus grammatically stable.
Taphrina's asci are lined up in layers on the leaf surface without any protective covering; therefore they are termed “naked asci”. So guess what name my Plant Pathology student volleyball team chose? Indeed, our t-shirts sported botanically correct drawings of Taphrina's asci, causing the other teams to think of us a bunch of weird science nerds. Nerds who played a pretty good game of volleyball mind you!
So what can you do to keep your trees healthy? Here are a few tips.
- If you are thinking of planting a peach or nectarine tree, investigate whether resistant varieties are available so you can avoid the problem altogether.
- For established trees, fall pruning of diseased shoots may help.
- Also for established trees, (organic) copper fungicide sprays in late fall after leaf drop and before budbreak in the spring may help.
- Addition of a horticultural oil may improve spray coverage. Be sure to follow the instructions on the label carefully.
If your tree got whacked by the disease, infected leaves will fall off and new leaves will develop but this requires the tree to expend additional energy. A foliar fertilizer application as well as fruit thinning can help the tree recover.
- Author: Cris L. Johnson
The Entomology Association of Southern California will be holding a quarterly meeting at the Los Angeles Arboretum. These meetings address a variety of entomological related subjects relevant to local and state pest issues and are a great way to meet and share information with other individuals who are interested in this area of science.
Presentations for this meeting will cover:
- California's invasive slugs, future threats & some novel approaches for their control
- Asian Citrus Psyllid research at California Polytechnic University
- County Reports
- Natural history and IPM practices for use against an atypical stink bug, the Bagrada bug
- GIS database of land gastropods of California - native and not
This association has an annual membership fee of $45. Memberships cover annual registration for all four quarterly meetings in December, March, June and September.
If you are interested in attending:
Date: March 4, 2014
Time: 8:15 am - 3:00 am (presentations start at 9:00 am
Los Angeles Arboretum
301 North Baldwin Ave.
Contact: Dr. Jim Downer, 805-645-1458 or firstname.lastname@example.org
See here for the agenda.
- Author: Cris L. Johnson
Support the agricultural community with the "Ventura Spray Safe" event. The Farm Bureau of Ventura County is seeking support for this event designed to educate agriculture industry workers and the general public about safe pesticide spraying practices.
While attendance is free of charge it also relies on donations to ensure its continuance. If you are interested in attending or contributing...
When: Thursday, March 6, 2014
Where: Ventura County Fairgrounds, Agriculture Building
Cost: No cost to attend, but contributions welcome
Contact: Brian Benchwick, 805-432-1182
Why: To promote practices to decrease pesticide-exposure incidents for sprayers.
For more details please see here.
- Author: Cris L. Johnson
The event was sponsored by the Santa Barbara County Flower and Nursery Growers Association and included a barbeque lunch as part of the registration fees.
The workshop was designed to assist greenhouse and nursery growers evaluate their water quality management practices (BMPs) and implement an Integrated Pest Management (IPM) Program. Information was provided to assist growers in conducting a self-audit of current water quality management practices, developing a farm water quality plan and implementing an IPM program to reduce impacts on water quality.
UC and ANR manuals and resources were used to supplement the presentations. Continuous education credits were also requested for participants.
- Author: Chris M. Webb
Many weed species commonly found in California can be found on the UC IPM website. The site is designed for easy identification.
The identification process is separated by type of weed – broadleaf, grass, sedge, and aquatic. Each of these sections includes: tutorials, high quality photos at multiple life stages, common and scientific names, and recommend management practices.
Resources for home gardeners and agricultural producers are available.
We also have our own website with all the local weeds that was compiled by Susan Latham, UCCE Master Gardener.