Sherwood Stolt

Thanks for the inputs that helped me narrow the cause of what I was seeing enough to ask a local Master Gardener and get the following reply:

"The described raining droplets from blackberry leaves in sun are most likely a classic case of guttation, not a sign of disease or pest, and are normal for a well-watered, vigorous plant, especially under fluctuating temps and humidity. Just monitor for overall plant health and don’t worry unless additional stress symptoms appear.  

What Causes Guttation?    
Guttation occurs when plants expel excess water through specialized structures called hydathodes, typically at the leaf margins or tips, but can also occur on other parts of the leaf surface. This process is driven by root pressure, which develops when soil moisture is high (such as with diligent irrigation), the air is humid, and transpiration is relatively low (often overnight or early morning but can also occur with rapid temperature/humidity changes). In some cases, the droplets are seen “springing” due to the force of expulsion and local microclimate effects on the leaf surface.
 
Why the Droplets Spring or Arc    
While guttation usually presents as droplets forming at the leaf edge or tip, in some plants or under strong root pressure (which is likely during heavy irrigation and hot, sunny conditions), droplets can be forcefully ejected, creating an arcing effect as described. Since the plant is well-watered and temperatures fluctuate, water uptake at the root may exceed what the plant can release by transpiration alone, so guttation pressure pushes droplets visibly outward.  
 
Is This a Problem?    
Guttation is generally not harmful and does not indicate disease or pest infestation. It simply means the plant is taking up more water than is leaving via stomata. However, if guttation is extremely frequent or copious, it can indicate overwatering, and long-term, excess mineral residue from the droplets (especially if using hard water or fertilizer) may slightly irritate delicate leaf tissue. Additionally, on rare occasions, guttation droplets can harbor bacteria or fungal spores; if these are reabsorbed, leaf spots can develop, but this is uncommon.
 
What to Do  
• No action is usually needed if the plant appears otherwise healthy and is fruiting well.
• Maintain good soil drainage and monitor irrigation, especially in high temperatures.
• If large amounts of guttation persist, consider reducing watering frequency slightly and check for sticky, white, or crusty residues on leaves (this indicates mineral accumulation)."

I guess I hadn't noticed this before because the droplets are so fine and difficult to see and so probably do happen on other plants.  At least I know these plants are getting plenty of water.  

It was about 3:30PM so near the day's peak temp.  The irrigation system was scheduled to run that evening and has automatic ET adjustment.  I haven't check soil moisture with a meter in several weeks but it should be in a normal range.  

The tree is about 40 feet away and there was no wind.  I also looked to see if they were coming from above and just bouncing off the leaves, maybe coming from the evergreen or the cottonwood, but I couldn't see anything coming down from above.  If I see it again maybe I'll get a ladder out so I can get closer to the leaves to be sure they are not falling out of the sky.  The droplets were so small I didn't even feel them when they landed on my hand.  I suppose they could be solid like maybe pollen or spores but would have to be about as dense as water to fall that quickly.  Pollen counts have been low lately but the sword ferns are producing clouds of spores, maybe those are big enough to see.  I guess I could  put a glass slide out to collect some.  

I checked and the temperature at the time was 92F and humidity was 42%.  The sky was clear and the sun shining on the top surface of the leaves where the droplets were coming from and so I don't think it was some sort of condensation.  My difficult to see video is linked below.  In the first few seconds of the video look at the evergreen tree in the background to see the tiny light specks falling down.  These were springing up from the top surface of the leaves with enough velocity to travel up several inches then arc over and fall.  
https://www.facebook.com/share/v/1CtmKGyGYJ/

I recently saw something I don't understand.  I was standing next to a blackberry vine looking up on a hot sunny day with a dark evergreen tree in the background and saw some very small droplets of moisture springing up from the tops of the leaves a few inches and falling down.  A steady drizzle of them.  How/why would a plant do that?
The vine is growing and fruiting well.  There was nothing coming down from above the vine and no breeze.  I tried to take a video with my phone but the droplets were so fine they did not record well.  I'll try to get that posted later.

Maybe crimson clover.  It's an annual but reseeds well, can be contained by mowing around the edges and is a nitrogen fixer.  

I don't know what the requirements are for your area but in my Western Washington area any land development that disturbs more than 7000 sqft of land or involves removing vegetation form areas that disperse runoff from driveways or roofs would require a permit.  That would likely involve hiring an engineer to either meet the prescriptive requirements of an 1100 page design manual or do a detailed computer model analysis.  However, since your roof runoff is just aimed downhill it sounds like your property has never had to meet such requirements.  

Your roof drains seem to just end in an open area.  There should be some sort of splash block or rock pad at the end of those drains to disperse the flow and then to prevent downhill runoff that open area should be 100 to 200 feet of native vegetated flow path.  I suspect that is contributing to the wet area below.  The prescriptive method to fix that would be to break up the soil to an 18 inch depth; mix in a lot of compost; plant with native trees, shrubs and groundcover and cover with mulch following a down slope line from the drain ends.  

You didn't mention what the deeper soil conditions are.  The several feet of water that falls on your impervious areas each year has to end up somewhere.  Diverting it onto your neighbors property is usually not allowed.  If your soil can't infiltrate it then it will pool at the surface.  Is your road is acting like a berm to retain the water but occasionally spills over?  If so adding more soil might just make more mud and make the road worse.  Maybe you could turn the southern part of the wet area into a rain garden that would better infiltrate the water.  You might be able to shift some soil around while building that.  

You say that the incoming water temp is 8C in winter and 25C summer.  Seems like that is adding a big load just when you don't need it.  Maybe you can find an affordable way preheat the incoming water, maybe an uninsulated tank located indoors that would warm up to room temp.    I've also seen schemes for DIY flat panel collectors located on a south facing wall and so better optimized for winter use.  

We have power outages about once a month, mostly caused by trees falling on power lines, usually for less than a day but occasionally longer.  We got by for the first year without a generator.  We have a well and the 86 gallon captive air tank was originally set to vary from zero to 28 gallons of water in it and so did not provide a reasonable short term water supply.  I reduced the captive air pressure when empty from 40 psi to 30 psi.  That makes the pump cycle a little more often but makes sure there is at least 20 gallons still in the tank at the low pressure end.  

The septic system has both a fluid pump and an air pump.  The pump tank has about five days extra emergency capacity at typical usage but one time the circuit breaker popped and we didn't notice for a while.  The tanks flooded without backing up into the house and continued to drain to the leach field and so I guess we could get by for as long as we have water.  

It seems that the modern GFI/AFI circuit breakers occasionally trip on the power outages for no apparent reason.  Whole house surge protectors don't seem to prevent that.  I now have several UPSes and I've also learned to check all the circuits every power blink and make sure the light on the front of the freezers is on every night when I go to bed.  

So far our natural gas line has never lost pressure.  

We did get a generator.  It doesn't prevent the first 15 second power drop, doesn't power all the circuits like the air conditioning, dryer ...  and is only supposed to be run 200 hours between scheduled maintenance and so isn't an extended off grid solution.  

One frustrating issue is the that cable TV and internet goes down whenever the power goes out.  In fact the cable company's DVR refuses to run if there is no cable connection and so we can't even watch anything we have previously recorded.  At least the cell phones usually keep working.  

Interesting "essential guide".  However, I would have liked to see some discussion of the native beaked hazelnut, Corylus cornuta, that I have many of around my lot.  They are a variety of sizes from a medium shrub to 15 foot tall and 20 foot wide.  I have rarely seen a few hazelnuts but most years there aren't any.  I would like to know what if anything I could do to produce better yields.