Jacarandas and June Gloom

Jacaranda in bloom.

Jacaranda in bloom.

As the growing season kicks in, two things happen in stark juxtaposition: The days get gloomy, and at times balmy. At the same time, one of my favorite trees, the Jacaranda, comes into bloom in vibrant light purple flowers.

Unfortunately, this is no time to revel in my oasis of bucolic bliss (not that I could, because one slight turn of the head and I see the bustling freeway…).

Evil is afoot: Powdery Mildew’s insidious and often rapid advance, requires vigilance and quick action.

Powdery hit my Aglianico hard in 2010 and 2011. The Montepulciano seemed more resilient. Until this year….

So on my birthday, I left my baby son with my parents, mixed up some sulfur, filled up the backpack sprayer and huffed up the hill to fight the year’s first battle with PM.

This is not a difficult task, but it gets messy and does leave a lingering stink on clothing and skin.

I use Bonide elemental sulfur with an agricultural surfactant. It takes two trips with my 4-gallon backpack sprayer to cover the 10 rows of wines.

Sulfuring the vines.

Sulfuring the vines.

You get what you pay for. My sprayer works fine, but when I have it filled to capacity, the solution overflows through the top and runs down my back.

It really does not smell too bad until I get in the shower. The clothing worn for the task needs a few cycles in the washer and a day out on the clothesline. But it must be done. An infected vineyard can take a big hit to its crop.

(A similar capacity sprayer would cost close to $100 at a hardware supply retailer, instead of the $40 I paid for mine on eBay. I have learned to stick to my budget. I’m not looking to make a small fortune, but I don’t want to sink one into this project, either). 

I’ll be brief in discussing PM here and refer to the full online resource.

Powdery mildew and its spread are driven by heat and not so much moisture. For every day the temperature stays above 70°F, the disease pressure goes up. And the mold spreads. Of course, moisture and humidity are a factor, but second to the heat. June Gloom, then is like jet fuel for PM in Southern California.

The UC Davis site, linked above, provides some useful tools to calculating the PMI (Powdery Mildew Index) and offers some interventions as well as a helpful spray schedule. I have not started to calculate the PMI and have been going by what I seen in the vines. because I still need to get an updated weather station in the vineyard.

Powdery Mildew spray schedule.

Powdery Mildew spray schedule (UCD IPM site).

My next post will detail the extent of damage PM can inflict. It will illustrate why I will be lugging that tank up the hill more often.

Ultimately, though, I cannot spray more often than once a week – event when there is a full-blown epidemic. When temperatures exceed 85°F, caution is advised so as to not burn the vines. While not a fatal injury, it is to be avoided. My approach has been to pick a day when two or more subsequent days are forecast to be under 85°F, and spray in the afternoon – around 4 or 5 pm. This buys some extra time without excessive heat.


June 8, 2012:

I have uploaded a video illustrating one thing that can help improve canopy ventilation:



Father, husband, physician, amateur guitarist, wine lover, wine writer, wine grower and wine maker trying to do it all within eye shot of downtown Los Angeles. http://www.shutupandmakewine.com http://twitter.com/Dr_Arthur_P
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8 Responses to Jacarandas and June Gloom

  1. Frightened Turtle says:

    Have you tried oils as an alternative to sulfur? I noticed PM rapidly advancing in my two year old vines (doesn’t seem to bother the one year olds). I applied a sesame/fish oil mix I got from Home Depot (2 tablespoons per gallon water) and it seems to be working very well. Also sprayed my one year old’s for good measure. The plan is reapply every two weeks. I would be interested in any recipes for oils that can be made from kitchen ingredients (rather than pay the $14/quart for the Home Depot variety).

  2. Frightened Turtle says:

    Yep, you don’t necessarily want to go back and forth between sulfur and oil. I use a systemic treatment for GWSS (obtained the dose/100 vines from a friend in the business and recalculated for dilution in two gallon/vine doses applied to recently watered vineyard – all mixed and applied by hand). So no issues with foliar application of oils interfering with GWSS control. Not sure what oils are best but a google search suggests it is a good strategy in general.

    • SUAMW says:

      Yeah. I have a mazzi injector that I need to install. Then inject imicloprid into irrigation. I looked at the concentration of the stuff sold as systemic and the stuff sold as foliar and I can basically just use a bigger volume of the foliar (and save a few bucks, but more importantly, I can buy the foliar stuff but not the systemic stuff).

      The oils I found at OSH are not what is on the IPM site (linked in this post). I have an ongoing discussion about alternatives on Facebook. Look me up if you’d like.

  3. SUAMW says:

    I uploaded a related video to my YouTube Channel and embedded it in the bottom of this post.
    Direct link: http://youtu.be/I7AyEqmDRHE

  4. Mel Ellis says:

    I’d be interested in your opinion on two things.
    Now that the growing season is with us, you can see the problem that allowing tendrils to grow means that the canopy becomes an entangled mass. I therefore normally cut them off and from your video I would think you agree?

    Secondly, also to tidy up the canopy and allow air to circulate, I normally cut off any flowerless canes at 2 or 3 nodes (leaving only the flowering canes to grow fully). This doesn’t seem to have any effect of the grapes but I am worried that the stumps of the “blind” canes will not produce flower bunches in the following year. Have you any experience of this? Would I be better off removing any flowerless canes completely?

    • SUAMW says:

      Depending on the trellis type and the number of vines you have, cutting tendrils is a good idea – ** especially if you are not in your vineyard daily**. If your vines get overgrown, evaluate your watering schedule. Nothing drives growth like early season over-watering.

      Shoot thinning is also appropriate, and varies with training style. I pull or cut them at their bases.
      To my understanding, each bud has some precursor cells that will give shoots. I do not know if cutting shoots down to 2 or 3 buds affects flowering in the subsequent season.

      I recommend checking AJEV for that.

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