Help for the Home Gardener from the
Help Desk of the Master Gardeners of Contra Costa County
Client's Question and Request: Hi, the pink fungus-like growth in the pictures below is spreading on my oak tree leaves. Can you advise? I have seen a little bit of this in the past, but this year it's really spreading fast; if you look at my tree from further away it is starting to have a pink cast, so there's a lot of this stuff! Thanks for any help you can give.
MGCC's Help Desk Response and Advice: Thank you for sending us the photos of your oak tree. What you are seeing are galls which are distorted, sometimes colorful swellings in plant tissue for which there are many causes such as wasps and other insects, fungi, nematodes, parasitic plants, etc.
The gall in your photos is one is one of the more spectacular galls seen in our oak woodlands and was recently observed in Hidden Lakes Park in Martinez. It is caused by an insect called a gall wasp which is about the size of a fruit fly. The wasp lays its eggs in the leaf. The developing larvae provide substances to induce the tree to form galls which provide shelter and food for the larvae. There are over 100 species of wasps associated with California oaks, and a species such as the Valley Oak or Blue Oak can have many different wasps associated with it. Each of these gall wasp species lays its eggs not only on specific parts of a tree, but also on certain species of oaks. For example, gall wasps associated with blue and valley oaks do not occur on coast and interior live oaks.
From your photo, it appears that your tree may be a Blue Oak (Quercus douglasi), in which case the Crystalline Gall Wasp (Andricus crystallinus) may be causing the galls you are seeing. The Iowa State University Bug Guide has photos of various galls, including that of the Chrystalline Gall Wasp which might help to confirm what you are seeing http://bugguide.net/node/view/145049/bgimage.
Your photo shows some galls which are fuzzy and some which are smooth. The UC publication "Oak Woodland Invertebrates" describes Chrystalline galls as pink to reddish, often densely covered with reddish or brownish hairs. And notes that if the larva of the gall fails to develop normally, possibly due to parasite attack, the fuzzy hairs are not produced and the galls remain bare. If you would like to bring a sample of your oak leaves with galls into our Help Desk office, we can look at them under the microscope and might be able to confirm which gall wasp species is on your tree.
While a few types of galls can cause limited leaf or twig die back by blocking the vascular tissue, most wasp galls cause little or no lasting damage to oaks. For more information on oaks and their insects and diseases, you might want to download a free pdf copy of the USDA publication titled "A Field Guide to Insects and Diseases of California Oaks" http://www.suddenoakdeath.org/pdf/psw_gtr197.pdf.
It is hard to believe that such a tiny insect is able to create so many galls on one tree! A recent issue of Bay Nature Magazine included an observation written by Ron Russo, retired Chief Naturalist for the East Bay Regional Park District, which highlights the magnitude and significance of such a tiny insect.
"On the east side of Briones Regional Park, in the late 1980s, I found a blue oak that stood about 30 feet high and looked quite healthy. But this tree supported a huge population of the cynipid wasp (Andricus kingi). Its red, cone-shaped galls covered every leaf that I could see–all the way up into the canopy, a dozen or more galls on each leaf. I calculated that a modest-size tree with 10,000 leaves could easily support 120,000 gall wasps of just this one species, excluding any other gall insects and their associates. Then by adding conservative ratios of gall parasites, hyperparasites (insects that attack parasites), and inquilines (insects that eat gall tissues, but will often kill any insects they confront inside the galls), I arrived at the astonishing number of just under 200,000 insects using one blue oak as a result of A. kingi galls and larvae. Even if these numbers are conservative and reached only during cycles when populations for a species are at their highest, perhaps once every five to 10 years, the ecological significance of a single blue oak–and blue oak woodlands–begins to come into focus."
You might want to monitor your oak tree and contact us again if you see significant twig die back. Otherwise, the galls are just part of nature.
Enjoy your tree.
Help Desk of the Master Gardeners of Contra Costa County
Note: The 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: email@example.com, or on the web at http://ccmg.ucanr.edu/Ask_Us//span>
- Author: MaryJo Smith
It is tempting to pamper our plants through frequent fertilizing and watering to ensure that they grow big and lush. It understandably gives us a lot of pleasure and sense of accomplishment to see our plants thrive and bloom, or produce a bounty of fresh juicy fruit and vegetables. But, with a drought situation, now is not the time to pamper your plants. Now, is the time for tough love. Your plants might not like it much. They might become "petulant" by withholding their lushness, not flowering like before or not producing as much. But, they will survive.
Most of us unknowingly over-irrigate our plants, so its ok to reduce the water you give them. In fact, the amount of water given to plants can often be reduced by 20-40%. Most established landscape trees, shrubs, and groundcovers, regardless of the species planted, perform acceptably well with 20-40% less irrigation than they are typically given.
To reduce irrigation with the least harm to your plants, water infrequently and deeply. Do this by increasing irrigation runtimes and extending the number of days between irrigation events. I know this seems contrary to the idea that you should reduce the irrigation runtime and keep the same frequent irrigation interval, but this will work.
Schedule slightly longer irrigation runtimes so that the entire root zone of plants is rewetted at each irrigation; then gradually increase the interval between irrigation runtimes over a few weeks. This practice will allow you to save water while allowing your plants to adjust to a new watering regiment. After extending the interval between irrigations, the water budgeting or seasonal adjust feature found on many sprinkler controllers can be used to fine tune runtimes and achieve optimum water conservation.
When watering, consider the root systems of your trees, plants, shrubs and lawns:
- Tall fescue lawns normally have roots 6 to 12 inches deep
- Bermudagrass and other warm season grasses are normally at least 12 inches deep
- Trees, shrubs, and groundcovers are normally found within 12 to 24 inches of the soil surface
- Vegetables vary in depth from 6 to 48 inches (a chart that shows the root depths is linked below for you)
Adjust the runtimes in your irrigation controller every month to account for changes in the average weather conditions. This alone can reduce landscape water use by up to 10%.
It is important to gradually reduce the water over a few to several weeks so the plants can adjust to less water.
Try to irrigate during the very early morning hours (between 2:00 am and 6:00 am) because evaporation is lower and usually there is little, or no, wind to disrupt the pattern of sprinklers during these hours if you are watering lawns. In addition, water pressure is a little better for irrigation systems during this time.
To find out how deep the water is going into the soil, take a long screwdriver (or similarly shaped tool or soil probe) and probe the soil in several spots an hour or so after an irrigation. The depth that the screwdriver or tool can be easily pushed into the soil is the depth that the water has penetrated. If deeper wetting is needed to wet plant roots, then additional irrigation cycles are needed. If the soil is wet beyond plant roots, then the runtime should be reduced.
Checking the soil moisture each day during drought - or really hot, dry days - with this technique and watching the plants for signs of wilt or water stress will enable you to see how long it takes for soil to dry to the point where water must be replaced. This is the maximum interval between irrigations for the current season. Ideally, irrigation is applied just prior to the onset of plant stress, so schedule irrigation about one day shorter than the maximum interval.
Note: Established small shrubs or groundcover are those that have been in the ground for a period of one year or more. A tree or larger shrub must be in the ground for at least 3 years to be considered established.
To determine the root depth of your herbs & vegetables, go to: Herbs & Vegetables Root Depth Chart
- Author: Kathy Gage
This segment will discuss remaking our back yard. We also took on the project of replacing our front lawn once the backyard renovation was mostly complete, but more on that in the next post!
In late 1996, my husband, two children, and I moved from Montana to San Ramon. In Montana, we had tried to make a living in a rural setting, but “You can't eat the scenery", I learned too late. When we moved to San Ramon, for a variety of reasons, we needed to find an empty house read for immediate possession. The house we bought came with a big backyard pool. We certainly enjoyed having the pool for many years, but once the kids were out of the house, we didn't use it much. The solar panels used to heat the water meant the pool was only hot enough to swim in from mid-May through September. While the maintenance costs weren't astronomical, we spent plenty to keep it in good condition. Other swim venues were very close at hand – San Ramon's huge swim complex is right over the creek at California High School – and I belonged to 24 Hour Fitness so I could swim there in an indoor pool any time of day.
At the time of the pool's deconstruction (as I like to call it) I was in the midst of my Master Gardener training through Contra Costa County and University of California County Extension Program (UCCE).
I knew from my MG training I wanted to have raised vegetable beds and to plant easy-care plants and shrubs. Since we live near the entire spectrum of K-12 schools, we also decided to add lawn for salability purposes. Many parents would want to have a play space for their children.
Our house is a typical tri-level suburban house that sits on a 70' x 100' sf. lot. In my Soils class, I learned our house sits on clay soil with no nutritive value, suitable only for supporting a 1500 sf. house. I would have to bring in lots of good stuff if I expected anything to grow! Because of San Ramon permit requirements, we had to replace our pool, and concrete decking with the same type of soil our house sits on. We had a soils engineer overseeing the placement and compaction of soil trucked in from the East Bay Hills. Only the final 12 inches could be ‘living' soil we could plant ornamentals and trees in. We were assured the soil was decent, though we might want to add compost and other amendments to attract worms and the like.
The hillside at the back of the property was covered with mulch, which was easy to live with and easy to replenish as necessary. The landscaper first moved the mulch to the level surface around the grass and the raised beds, and then added soil to the hillside. I have since added a lime tree, two miniature agapanthus plants, and three pittosporum bushes to the hillside, and creeping rosemary and white yarrow against the date palm behind a stone wall barrier. The fourth side, along our other neighbor's fence, now has agapanthus, two rhododendrons someone gave me, a transplanted ornamental onion set, and in the corner, a leafy grape plant that so far does not bear fruit but turns a lovely red on the fall. My neighbor's vinca minor has been creeping into that corner as well, and I am doing my best to encourage it.
My two planter boxes hold a mishmash of plants. Last year's crop of heirloom tomatoes, tomatillos, various peppers and artichokes were a wash-out due to the lack of enough hours of sun. Now I am using the beds as a nursery of sorts, to grow small plants and seedlings for re-planting elsewhere. I also have one artichoke that is blooming, and some red onions and garlic that I expect will make it and be edible
I have barely touched the surface of my efforts, but I am happy to know that every plant is there because of me. It's okay if some die, because I know where I can get more. I have to admit I did not enjoy the work initially because I had so little confidence. I thought I had a ‘black thumb.' Now I know that is not true. Although I have a long way to go to become a ‘master' master gardener, I know I can accomplish what I set my mind to achieve. And boy, oh boy, is that a great feeling!
Next chapter: My front yard conversion: a lot more work that continues to this day!
Client's Question and Request:
I'm in central county and growing Zinfindel Grapes in my backyard garden. The vines are now several years old and producing fruit this year. The grape leaves have now developed “blotches” and the grapes look “cloudy” and not very healthy. What's the problem and what can I do about it? The pictures below show the leaf damage and what the grape bunches look like.
MGCC Help Desk Response and Advice:
Based on the grape samples and the photos you provided, the problem with the grapes appears to be powdery mildew.
Powdery mildew is a common fungal disease on grapes. It first shows up as faint white powder on the grapes but later can progress to cause brown russeting on the developing grapes. That russeting was somewhat apparent on the grape samples you brought in. Affected fruit cannot ripen normally and may crack as it grows.
Shady conditions and lack of good air circulation favors the development of the disease on grapes. When the vines are pruned iduring dormancy so that shoots are positioned in the next growing season, try to prune so that the plants will allow exposure of the developing fruit to sunlight and good air circulation. Avoid overhead watering of the vines which can spread the fungal spores to new locations.
Next growing season, watch closely for the appearance of powdery mildew. Early signs of a developing problem include young emerging leaves being deformed or showing a puckered condition. Prune out such areas as soon as they appear and it may help to prevent new infections.
If you lose a large percentage of the grapes this season, you may also want to consider the use of fungicides to prevent a recurrence next year. Take a close look at this UC website which gives detailed information about different types of fungicide that can be used and includes directions on how and when they should be applied: http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7494.html
We hope this information is helpful. You're welcome to contact us again with any further questions
Help Desk of the Master Gardeners of Contra Costa
Note: The 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: firstname.lastname@example.org, or on the web at http://ccmg.ucanr.edu/Ask_Us/
- Author: Molly K Weden
One day recently, a client at the nursery where I work brought in a sprig of Salvia mellifera, Black Sage. She said it was all over her sages, all of them! The plants seem otherwise healthy. They are in a sunny spot, receive drip irrigation not too often, and were fine for years up until now.
Looking closely, I guessed it might be some kind of gall. We picked and poked at the protuberances and put it under our low power microscope, which revealed that the growths were tubular.
What is all over her Black Sage?
It is a midge - Rhopalomyia audibertae - that creates a gall on sages.
The plants affected by this little gallfly are Salvia melllifera - Black Sage, and Salvia apiana - White Sage. Many creatures spend part of their life cycles in a gall. Mites, certain aphids, moths, flies, and wasps are just a few. Their eggs are deposited on the plant, and when they hatch, the larvae start to eat.
It is not clear how the larva affects the plant tissue, whether it is secretions from the mouth or the other end! The plant tissue changes in weeks or months to envelope the little creature. It becomes a protective enclosure for the larva while it grows. Fortunately, it doesn't harm the plants. It just looks ugly.
In this case, the gall is a member of the Dipteral order of insects, a tiny fly – or midge - that borrows the leaf tissue of a couple familiar sages. There is another midge, of the genus Rhopalomyia, that looks similar, but it employs the Baccharis group of Chaparral plants, such as coyote bush, as its host. The midge on the Black Sage is Rhopalomyia californica, the Baccharis gall fly.
These creatures don't hurt the plant, and the distorted leaves can be cut back if desired.
For further information on galls, see:
UC_IPM Managing Pests in Gardens: Gall Makers, http://www.ipm.ucdavis.edu/PMG/GARDEN/PLANTS/INVERT/gallmakers.html
Bugguide (Hosted by Iowa State University Dept of Entomology), http://bugguide.net/node/view/376111
The Gall Midges of California Essig Museum of Entomology,essig.berkeley.edu/documents/cis/cis02_2.pdf