- Author: Michelle Leinfelder-Miles
- Author: Ben Faber
The drought has caused numerous conditions – physiological and pathological – that I have only seen in text books (see our newsletter article: http://ceventura.ucanr.edu/newsletters/Topics_in_Subtropics63007.pdf). But other phenomena are also occurring. Recently I saw a field of blackberries in full bloom and the other day a grower called in about a plum tree that was also in full bloom. What is going on? This is supposed to happen late winter/early spring. It turns out that often drought stress can supplant winter chill in some plant species. In this case, these two species are relatively low chill, meaning they don't require a lot of cold to break winter bud dormancy. The drought stress causes the buds to break dormancy.
This is similar to the “Verdelli” effect in lemons. This is a technique used to shift the period of optimum fruit production to a more profitable period, usually the summer when more lemons are used. In the case of plum and blackberry and other low chill deciduous tree crops, this would be pushing production into the coldest period of the year. It might work along the coast, but in the Central Valley it would probably just mean frozen fruit. But it's a possible method that we might play with.
Photo: October, 2016
![plum blooming in fall plum blooming in fall](/blogs/blogcore/blogfiles/39542.jpg)
- Author: Erin Mahaney
Last week, my husband came in from the sideyard where I store my unused plant pots and asked, “Did you know your amaryllis is blooming?” I responded, “What amaryllis?”
Sure enough—I have a beautiful amaryllis blooming in August! What a treat!
Each year I buy an amaryllis bulb for the holidays. Even though I know that amaryllis bulbs can bloom again, my approach to post-bloom care is haphazard at best. When the plant is done blooming, I put it outside and water it for a few weeks or months until it dies back completely. Sometimes I don’t water it at all. Either way, eventually I set the bulb aside and forget about it completely. Occasionally, a bulb will bloom again in late fall or around the holidays. But in August?! Apparently I started the dormant period a bit early this year. Anyway, it was a delightful surprise!
If you are interested in the correct way to make an amaryllis bloom again (including deciding when you want the plant to bloom) you can find a fact sheet on the United States National Arboretum’s website at http://www.usna.usda.gov/Gardens/faqs/AmaryllisBloom.html.
Now, I’m off to check on my other amaryllis bulbs!
![The August Amaryllis. (photo by Erin Mahaney) The August Amaryllis. (photo by Erin Mahaney)](/blogs/blogcore/blogfiles/12482.jpg)
- Author: Betty Victor
I went out to my backyard this morning to see if the rain and heavy winds we had did any damage to my plants. Everything look ok, soggy but maybe the sun will shine and dry things out some.
A pleasant surprise greeted me, my tree mallow (Lavatera spp.) is starting to bloom. I planted it last year from a cutting that I got at our plant exchange about two years ago. I took about 3 cuttings home and put them in some potting soil and waited to see if they would take. The larger one did, the smaller ones did not. Once it starting growing as was about 12 inches tall I transplanted it to the garden. I put the tree mallow in a spot where it would have room to grow, as I had seen one that looked like it would take over, and I didn’t want that to happen. But it looks like it has a mind of its own, and is taking over that spot and one nearby it.
This is the first time it has bloomed, but it has stayed green all year, which is nice when most things look doormat. Even with this Lavatera blossom in the picture showing white with light pink it is actually a very light pink, with a darker pink around the center and the stamen is light yellow.
Some tree mallows are suppose to be rose shaped mine grows face down and to me it looks more like the old fashion hollyhocks that our parents might have grown. All I know is that this plant seems to grow inches over night and soon will take over in height and width, so after it blooms I plan on pruning it down to an average height.
![Lavatera in my backyard. (photo by Betty Victor) Lavatera in my backyard. (photo by Betty Victor)](/blogs/blogcore/blogfiles/10944.jpg)
- Author: Franz J.A. Niederholzer
As I write this, early bloom is just beginning to show in some prune blocks in the Yuba City area. Even though it has been a relatively dry winter, there is rain predicted starting this weekend (Mar 10-11) or early next week, so growers should prepare to protect their crop from disease at bloom -- especially brown rot.
When crop stage and weather indicate there is a need to protect a crop, make sure to rotate between different pesticide classes to reduce the risk of fungicide resistance developing in a disease population in your orchard. Using different FRAC (Fungicide Resistance Action Committee) group pesticides -- pesticides that use different modes of actio on disease organisims -- is the best way to manage fungicide resistance in your orchard. See the tables below for details on timing, relative resistance risk, and efficacy of many pesticides registered for prunes. The FRAC group or groups in a particular fungicide product are listed on the first page of the label.
In wet bloom weather, UC recommends a two spray program for blossom brown rot control -- once at green bud and once at full bloom. The full bloom spray is the most important, although the green bud spray should be included as well. At full bloom, include a captan or chlorothanil (Bravo, etc.) material for russet scab control. As stated above, alternate between FRAC classes with each application. For example, for blossom brown rot control, you could use Vangard (FRAC Group 9) at green bud and Tilt/Bumper (FRAC Group 3) at full bloom. In a wet year at full bloom, combining two fungicides in the tank -- one for brown rot and one for scab management (for example, Tilt + captan) -- is the best approach. Captan and chorothanil are effective for scab control, but only mediocre brown rot materials.
In a dry bloom season, research by Dr. Jim Adaskaveg, UC Professor of Plant Pathology at UC Riverside, has shown that effective brown rot control can be acheived with a single bloom spray at 50-70% bloom. This year is not shaping up to be a dry bloom. Hopefully that will help with fruit set!
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Table 1. Examples of general effective timing, resistance risk, relative efficacy, and target diseases of different FRAC group fungicides (alone or as mixtures) available to prune growers in California at the beginning of bloom, 2012. Low, medium, and high resistance risk groups are listed under “Low RR”, “Med RR”, and “High RR”, respectively. Stars after each mixture indicate relative efficacy of the product(s) – limited and erratic (*),moderate and variable (**), good and reliable (***), and excellent and consistent (****). See Table 2 for product names to match with FRAC numbers listed here. Consult with your PCA for specific fungicide application rates and timing(s) for disease control in your orchard. The information in this table is drawn from Efficacy and Timing of Fungicides, Bactericides and Biologicals for Deciduous Tree Fruit, Nut, Strawberry and Vine Crops, 2011.
Disease |
Green bud |
White bud |
Full bloom |
May |
June |
July |
Brown rot |
Low RR 2(+oil)**** Med RR 3/9**** High RR 3**** |
Low RR 2(+oil)**** Med RR 3/9**** High RR 3**** |
Low RR 2(+oil)**** Med RR 3/9**** High RR 3**** |
|
Med RR 3/11**** High RR 3****
|
Med RR 3/11**** High RR 3****
|
Lacy scab |
|
|
M4*** |
|
|
|
Rust |
|
|
|
Low RR M2** Med RR 3/9*** 3*** |
Low RR M2** Med RR 3/9*** 3*** |
Low RR M2** Med RR 3/9*** 3*** |
Table 2. Examples of FRAC groups (2, 2, 9, etc.) and FRAC group combinations (3/9, 3/11, etc.) available to prune growers in California at bloom, 2012. Always read the label before applying pesticides. Consult with your PCA regarding spray timing, rates, etc. Not all generic products available in the market are listed in this table.
2 |
3 |
3/9 |
3/11 |
7/11 |
9 |
11 |
17 |
M2 |
M4 |
M5 |
Rovral |
Tilt/Bumper |
Inspire Super |
Adament |
Pristine |
Scala |
Gem |
Elevate |
Sulfur |
captan |
chlorothanil |
|
Elite/Tebuzol |
|
Quadris Top |
|
Vangard |
Abound |
|
|
|
|
|
Indar |
|
Quilt Xcel |
|
|
|
|
|
|
|
|
Quash |
|
|
|
|
|
|
|
|
|
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The best single source for information on disease management tool efficacy and timing in California deciduous tree and vine crops is Efficacy and Timing of Fungicides, Bactericides and Biologicals for Deciduous Tree Fruit, Nut, Strawberry and Vine Crops, 2011 written by UC researchers/advisors J. Adaskaveg, D. Gubler, T. Michailides, and B. Holtz. Please follow the hyperlink in the title above to view this excellent, free document.
BloomFungcides.2012