- Author: Help Desk Team
This year was particularly bad for peach leaf curl and other fungal infections in fruit trees because of the wonderful rain we had last winter and spring. It looks like we might have another wet winter, so we are rerunning this post to remind you to think about a spray program for your trees.
Now that the leaves have fallen, or mostly fallen, from your backyard fruit trees, are you wondering whether you should apply dormant sprays?
“Dormant sprays” or “delayed dormant sprays” are terms used for the application of pesticides when the tree is dormant or just coming into bud swell. The pesticide could be a fungicide used to help manage fungal disease or a horticultural oil or oil in combination with insecticides to kill insects.
Don't assume that you need dormant spray. Before reaching for the spray, first determine whether your trees have previously had a disease or serious insect pest problem that can be managed with dormant sprays. Have you already tried all non-chemical recommendations for lessening the problem? Finally, evaluate the amount of damage from the disease or insect pest you experienced in the prior growing season to decide whether a pesticide is really needed.
Fruit tree diseases that can be managed by applying a fungicide dormant spray include peach leaf curl, brown rot, and shot hole disease.
Peach Leaf Curl
Peach leaf curl affects only peach and nectarine trees. It shows up in spring after the tree has leafed out. Leaves are thickened, curled, and colored red or yellow instead of normal green.
If your tree has had significant peach leaf curl in prior years, dormant spraying with a fixed copper spray just after all the leaves have fallen from the tree (usually December to January in our County) may prevent or reduce the severity of the disease. For information on managing peach leaf curl, see https://ipm.ucanr.edu/PMG/PESTNOTES/pn7426.html/
Brown Rot
Brown rot (Monilinia) is a fungal disease that can affect peaches, plum, cherries, apricots, and nectarines. In the spring blossoms on infected trees shrivel and die, often clinging to the twigs. Leaves at the base of infected twigs may also turn brown and die. Fungal spores attach themselves to developing fruit and show up as brown or tan spots on the surface of the fruit.
If your trees had significant fruit loss from brown rot in the prior growing season, a dormant spray of a copper-based fungicide may help. Apply it at the pink bud stage while flower buds are still tightly curled and pink in color. For more information on brown rot, see http://ipm.ucanr.edu/PMG/GARDEN/FRUIT/DISEASE/aprbrownrot.html.
Shot Hole
Shot hole (Coryneum blight) can affect plums, nectarines, peaches, cherries, and especially apricots. It shows up as small reddish holes on leaf surfaces. Often the holes turn brown and drop out. Fruits may also be infected. Where disease has been severe and cultural steps haven't helped, a fungicide spray following complete leaf drop may be needed. See http://ipm.ucanr.edu/PMG/GARDEN/FRUIT/DISEASE/shothole.html.
Brown Soft Scale
Insects that can be managed with dormant sprays of horticultural oils or oils mixed with insecticides include scale, aphids, and spider mites. Don't spray unless you have confirmed that the insects are present in damaging numbers and cannot be controlled by other means. Keep in mind that spraying may also kill beneficial insects which are the first line of defense against insect pests.
More information on controlling these insect pests can be found at these UC websites: https://ipm.ucanr.edu/QT/scalescard.html
https://ipm.ucanr.edu/QT/aphidscard.html
https://ipm.ucanr.edu/QT/spidermitescard.html
Caution: Before spraying, read and carefully follow the label instructions on the pesticides you use, including wearing recommended protective gear.
Help Desk of UC Master Gardener Program of Contra Costa County (TKL)
- Author: Help Desk Team
A poet once said, “A weed is but an unloved flower.” Sometimes though, a weed, an insect, or a four-legged critter can become a dangerous pest. In a state like California where so much of our economy is agriculturally based, these pests can wreak havoc. In our home gardens they threaten our landscape and ornamental plants and make the creation of natural areas a significant challenge when they displace native plants and wildlife.
Exotic and Invasive
California's native ecosystems were uniquely adapted to our Mediterranean climate, with its dry summers and wet winters. However, as the population changed and grew with immigration alongside increased international travel and commerce, new species of plants, many bringing insects and pathogens with them, were imported from Asia and Europe (often inadvertently) and introduced into the landscape. These exotic plants sometimes failed and sometimes flourished. Sometimes we move them unwittingly from state to state as we travel. The result is that some exotics have become invasive, spreading through the native ecosystem.
You might recognize some of these pests. The pathogen that causes sudden oak death was accidentally introduced on nursery stock and is estimated to have killed more than 1 million oak and tanoak trees over the last decade. In addition to disease, invasive plants can change the composition of soil as scotch broom does by adding nitrogen to the soil, or outcompete shallow rooted native species during dry summer months as the star thistle does with its deep root system.
Of special concern currently is the Asian Citrus Psyllid (Diaphorina citri), a tiny insect that attacks all varieties of citrus, and is a vector for the bacterium that causes Huanglongbing (HLB) disease. An infestation can spread quickly and there is no cure for HLB. Although the psyllid is rarely seen in Northern California, it has become a serious problem in Southern California where it arrived from Mexico in 2008 and is slowly spreading north. The USDA notes that HLB “has devastated millions of acres of citrus production around the world, including in the United States.” http://ipm.ucanr.edu/PMG/PESTNOTES/pn74155.html
Steps to Take to Stop the Spread
We can all have an impact on the spread of invasive species into our ecosystem.
1. Become familiar with invasive pests, how to identify them, and where to find information. The UC IPM website is a good source of information about managing exotic and invasive pests. https://ipm.ucanr.edu/Invasive-and-Exotic-Pests/
2. When you see suspicious organisms, get help identifying them. Contact your local UC Master Gardener Program Help Desk or Agricultural Commission to report invasive species and to get help with managing them. https://www.cdfa.ca.gov/plant/
3. Inspect new plants carefully before planting them. When possible, plant native species — they are better adapted to our climate, support butterflies and other pollinators, and are less likely to have pest problems! https://plantright.org/
4. Don't bring plants into California from outside the state, and don't purchase invasive plant species. This includes planting gifts from friends across the country into your garden, and ordering online from nurseries that are outside of California. https://www.cal-ipc.org/
5. Buy your firewood where you burn it. Many pest insects and pathogens move with firewood. Don't move it far from its source. http://www.firewood.ca.gov/
To learn more about the invasive species prevalent in California, their impact and how to address them, the UC IPM website is a wealth of important information. We can all make a difference in protecting our beautiful state.
Help Desk of the UC Master Gardeners of Contra Costa County (RDH)
- Author: Help Desk Team
Prune Apricot and Cherry Trees in August
If you have apricot, cherry, or related hybrid tree varieties such as aprium and pluot in your yard, plan to prune them before the end of August. This timing will help prevent infection by a deadly fungal disease called Eutypa Dieback that can kill these trees as well as grape vines.
When infected by Eutypa, branches or entire trees wilt and die suddenly, often with the leaves still attached.
Apricot tree with branch killed by Eutypa
Signs that your tree may be infected by Eutypa include darkly discolored cankers on the branches and oozing of amber colored gummy sap.
Eutypa cankers on apricot branch
Oozing Sap on Cherry Tree from Eutypa Infection
[Editorial Note: apricot photos downloaded from UC Repository. Cherry tree photocopied from UC ANR blog article by Chuck Ingels, UCCE Sacramento, https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=16014 ]
Many other varieties of trees and shrubs can become infected with the Eutypa fungus without showing disease symptoms or progressing to the dieback stage. These other tree and shrub varieties can serve as store houses for the Eutypa pathogens that could potentially spread to your grape vines and apricot, cherry, aprium and pluot trees. Trees and shrubs that can serve as reservoirs for the disease include almond, apple, blueberry, crabapple, honeysuckle, kiwi, oleander, pear, and certain native plants such as big leaf maple, California buckeye, ceanothus, and willow.
Eutypa disease is spread from an infected tree, shrub or vine to uninfected trees by splashing water from sprinklers or rain. The splashing water allows the fungal spores to enter through pruning or other wounds. Pruning vulnerable tree varieties by the end of August allows pruning wounds to heal and close before the typical start of the rainy season in Contra Costa County in late October. Also, avoid using sprinklers near recently pruned trees since water from sprinklers can also spread infections. Using these precautions will reduce the risk of infection for your trees.
Studies have shown that the Eutypa pathogens can also be spread on pruning tools that have been used to prune infected trees and shrubs. To prevent such transmission, be sure to disinfect your pruning tools before and after pruning.
To disinfect tools, soak them for thirty minutes in a 10% bleach solution (nine parts water to one part bleach). Bleach is corrosive so be sure to rinse the tools thoroughly with water after soaking. Then oil them. The bleach solution loses 50% of its effectiveness after two hours, so be sure to use a freshly mixed batch.
As an alternative to bleach, you can disinfect pruning tools with 70% isopropyl alcohol. Just spray it on your tools and it will kill any pathogens almost immediately. Alcohol is not corrosive, so you don't need to rinse it off tools.
An internet search for “how to prune apricot [or cherry, aprium or pluot] trees” will help you find videos that demonstrate good pruning techniques. Just be aware that most pruning videos are filmed when the trees are dormant. With no leaves, the branches can be more easily shown in the video to demonstrate pruning techniques. In California, you don't want to wait until the dormant season to prune these vulnerable trees because that increases the risk of an Eutypa infection. So, you'll need to adapt the pruning techniques to a tree that still has leaves.
For more information on Eutypa disease, visit this University of California IPM website: http://ipm.ucanr.edu/PMG/GARDEN/FRUIT/DISEASE/eutypadieback.html
Advice from the Help Desk of the
UC Master Gardener Program of Contra Costa County
i confess ... I'm a garden blog junkie.
As an avid gardener, I'm also looking to the (many) blogs I subscribe to for ideas on how to enjoy my gardening even more. While I hope you find this blog interesting, there are many other UCANR blogs that you might be interested in as well. Many of the most informative are posted quite frequently, while most are only posted occasionally. You can find the full list of UCANR blogs at http://ucanr.edu/blogs/blogcore/blogroll.cfm?sort=a. You will probably have to do some looking around to find blogs you will be interested in… but you can easily change your subscriptions at any time.
A recent blog I subscribe to -- UC WEED SCIENCE had some great advice on getting rid of garden weeds:
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Control garden weeds in early spring
Posted by: Gale Perez
Published on: April 14, 2016....From the UCANR News Blog...
UC Cooperative Extension IPM advisor Cheryl Wilen recommends swivel hoes over herbicides for weed control.
Wilen recommends home gardeners use a swivel (or hula) hoe to scrape the surface and decapitate weeds. “It's a bit of exercise,” she said, "but you can do it so quickly, it's not a problem.”
Another weed control strategy is a thick layer of mulch, with does double-duty by reducing water evaporation from the soil surface, thereby conserving water.
Wilen suggests a three- to four-inch layer of mulch be spread in garden beds and landscape borders before the weed seeds have a chance to germinate. Mulch blocks the sunlight weeds need to push through the ground.
Fabric weed barriers are useful for controlling particularly challenging weeds, like nutsedge. Wilen suggests covering the fabric with mulch for an esthetically pleasing weed-free garden.
Though the common herbicide glyphosate (such as Roundup) kills weeds and is safe if used correctly, Wilen prefers using the swivel hoe. "It's just quicker and easier than pulling out the spray equipment," she said.
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No use re-inventing the wheel for this blog with this advice… time to get out my hula hoe… and I found the link to the LA Times article informative as well.
So… for all you garden junkies out there… you might consider perusing and subscribing to some UCANR blogs to get your full daily “garden fix”.
UC Master Gardener Program's Help Desk
Note: The UC Master Gardeners Program of Contra Costa's Help Desk is available year-round to answer your gardening questions. Except for a few holidays, we're open every week, Monday through Thursday for walk-ins from 9:00 am to Noon at 75 Santa Barbara Road, 2d Floor, Pleasant Hill, CA 94523. We can also be reached via telephone: (925) 646-6586, email: ccmg@ucanr.edu, or on the web at http://ccmg.ucanr.edu/Ask_Us/ MGCC Blogs can be found at http://ccmg.ucanr.edu/HortCoCo/ You can also subscribe to the Blog (http://ucanr.edu/blogs/CCMGBlog/).
Advice from the Help Desk of the Master Gardeners of Contra Costa County
various life stages
photo: www.doyourownpestcontrol.com
I found this "bug" in my kitchen sink. Could you tell me what it is and what I should do about it?
Help Desk Response:
Thank you for contacting the Contra Costa Master Gardener Help Desk. I have inspected your insect sample, and suspect that it is a young (nymph stage) of an Oriental cockroach. This variety of roach prefer damp areas and cooler temperatures. They are most commonly found in single family homes surrounded by vegetation, and will come into homes in search of food. They are more slow moving than other roaches, and do not fly. Because of this, they will often be found trapped in sinks or bathtubs. Because Oriental cockroaches will take one to two years to grow to their adult size, you may be seeing only the nymph stage from a recent hatching.
photo: UCANR
I have included a link below from the UC Davis Integrated Pest Management website that will provide you with more information about roaches, including the most effective methods of control. A combination of baits, traps, sanitation, and exclusion methods are discussed.
http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7467.html
In the event that you decide to consult a professional exterminator company, I have also included this link providing information on how to choose a pest control company:
http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn74125.html
I hope you find this information helpful. Please do not hesitate to call us again if we can be of assistance.
Help Desk of the UC Master Gardeners of Contra Costa County
Note: The UC Master Gardeners of Contra Costa's Help Desk is available year-round to answer your gardening questions. Except for a few holidays, we're open every week, Monday through Thursday for walk-ins from 9:00 am to Noon at 75 Santa Barbara Road, 2d Floor, Pleasant Hill, CA 94523. We can also be reached via telephone: (925) 646-6586, email: ccmg@ucanr.edu, or on the web at http://ccmg.ucanr.edu/Ask_Us/
