Big Problem for “Water Throwers” Tonight (9:26am, Tue., 3/14/17)
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Fig. 1. If you are doing sprinkler irrigation alone, a digital thermometer can tell you when the blossoms are too cold. And, a reading of 29.6 would tell me you are getting pretty darn close to a serious problem!
My friend and colleague, Bob Rouse, has been encouraging me to think about maybe writing a chapter on Strawberry Frost and Freeze Protection. Here is something we might want to add to that chapter Bob: “If you are 100% reliant on sprinkler irrigation, and do not have any interest in using a row cover, be prepared for days and nights when you may have to run sprinklers without interruption for up to 37 hours.”
Wow, what a spring so far. Big night coming up tomorrow night. As you know, Danny and I are water throwers. Worked ok so far this year. Worried a little about the winds tomorrow night. Accuweather says 13 mph winds all night with a low of 22. Just about the worst case I can think of. I have seen what it can do to plants with winds keeping water off plants for a time during overhead protection. Wondering, if it gets real windy should I just not run water, lose the blooms there and press reset or risk throwing water and burning plants? I really hate to lose the hours and money already invested in these berries up to this point but don’t want to perminetely damage the plants. Your thoughts?
Here is what I wrote to a “water thrower” over in Durham area this morning:
- Biggest problem for water throwers is continuous pumping from about midnight tonight through noon on Thurday – 37 straight hours without a break
- The coldest morning is Thursday ( 22 F)
- Precipitation rate for 22 F and winds of 2 mph on Thur is 0.18 inch
- Tonight, your precipitation rate is closer to 3/10th of an inch because of these winds
Here is the AWIS Hourly pdf for Ral-Durham showing the rather unbelievable situation “water throwers” are facing: Durham Grower – 9
I don’t have a secretary, and I am not much of a typist, so I took a photo on my iPad of precipitation rates you need for dealing with these winds.
This table is available in this document as a pdf: StrawberryPlasticulureAdvisoryApril1505
I am not aware of anyone who has ever run a sprinkler irrigation system for this many hours? You would surely need to be thinking about back-up systems in case of breakdowns occurring. As I related in an advisory last night, I just learned of a grower in western piedmont who had done an amazing job keeping his strawberry blossoms out of danger until yesterday morning.
“Spent the last two weeks babysitting blooms. 7 nights sleeping in my truck. Had to run OHIRR 3 of those nights. Last night fired up for frost protection and blew a hyd seal on tractor. Heavy frost by the time I switched tractors. 2 weeks worth of work down the tubes.”
Winds and Sprinkler Irrigation
You would be really doing yourself a favor this morning to take a few minutes to read this: StrawberryPlasticulureAdvisoryApril1505
Winds and sprinkling just don’t go well together! And, then add record low dew points to the mix. Check this out, we are seeing NEGATIVE DEWPOINTS in Raleigh Durham starting at 4 p.m. (1600) tomorrow, and then they stay in single digits all the way through 6 a.m. Thursday morning. So, we have what I call the TRIPLE WHAMMY for Water Throwers: 1) Very cold temperatures; 2) High winds, and 3) Low atmospheric humidity as indicated by negative dew points!
You would need an irrigation system designed for EXTREME WIND AND COLD. Do you know for sure what the precipitation rate is for your system? Are you able to “nozzle up” (switch to larger sprinkler nozzles)? Do you have the pumping capacity to handle this? Remember, there is one more morning to go –> Friday morning has a low of 26. Another question is “who will be helping you?” This is a pretty long stretch with little or no sleep. I am especially concerned about the horrendous conditions you may encounter early Wed morning with 9 mph sustained winds and dew points of 10-17, there is going to be a lot of ice freezing up on nozzles — you may wish to spray a white lithium grease on nozzles…
A grower friend in Fort Mill, SC, told me of a trick to get frozen nozzles unfrozen, just put a gallon bucket over the frozen up nozzle and let some of the liquid water do the melting for you!
In the final analysis, I did not say to the Durham grower that “it could not be done.” Actually, it is doable. But, your system cannot fail. As they say, Failure is not an option.”
Assuming you have an excellent sprinkling system, and that you can achieve sprinkler rates shown in the table, AND keep the nozzles from freezing up, AND achieve uniform enough coverage all through the night on Tue/Wed, AND be able to run 37 continuous hours, AND the forecast doesn’t get any worse than this, then you have a shot!
This bears repeating: Your sprinkling system must be in tip-top shape, and you will need plenty of labor on hand tonight for knocking ice off of sprinklers when they “freeze up” due to conditions tonight that favor evaporative cooling problems (low dew points and high winds after sunset).
Regarding the uniform coverage idea, it is important to remember that each blossom needs to get a fresh coating of “liquid water” every minute. So, on a night like tonight, with winds starting out at maybe 15 mph at 6 p.m. (Ral-Dur AWIS), it would be excellent to be able to move irrigation lines CLOSER. I have a friend over in Richmond area who doubles up his lines and goes with 30×30 spacing for occasions like this one.
On this very subject, Tom Baker had these very helpful remarks:
RE: This morning’s advisory, tightening irrigation to 30 x 30’, and nozzling up…
We use HUNTER sprinkler heads on 30’ x 30’. Always have. Use the continuous-turning 360-degree heads (round and round and round without reversing). These sprinkler heads come packaged with many sizes of nozzles for a big selection of irrigation rates. I think the Hunter stuff is most commonly used in the landscape irrigation industry. Here in the Virginia Beach area, they are available at Turf and Garden.
We have NEVER had a Hunter 360 freeze up. Ever! Other parts of the system might freeze, but our heads/nozzles have never frozen up.
p.s. I believe the last we bought were “PGS-360” model.
The goal is to keep the ice clear!
Ultimately, though the best way to handle these incredible winds coming later today (Tuesday) is to throw on a row cover!
I know some growers are trying to get hold of some extra row covers today, and these are some of the suppliers to growers in our region of the country. I know there are others, and this is not a complete list. I am happy to list anyone who is a supplier. Just send me your info asap
Row Cover Suppliers:
*Berry Hill Irrigation
Row covers (Atmore Gro-Guard, Dupont Typar), hold-downs, row cover hoops, sprinkler systems 3744 Hwy 58
Buffalo Junction, VA 24529
*Coor Farm Supply Service, Inc.
Row covers (DuPont/ Typar and WinterBlanket) sprinkler systems, thermometers, frost alarms
O. Box 525 Smithfield, NC 27577
Crop Tunnels USA
334 Weeping Cherry Columbia, SC 29212
Eastfield Farms/Peter Perina
Row cover hold-downs
P.O. Box 275 Mathews, VA 23109 804-725-3948