Well, the late freeze hit here in GA as expected last night, most of the trees were at petal fall stage, hit the low of 26 for 2 or 3 hours. I ran the sprinklers from midnight last night until this morning, I guess I will know in a few weeks if the ice provided any protection
According to MSU at that stage you can expect 10% kill at 28F and 90% kill at 25F. So you are borderline for severe damage. You might have made a crop without protection.
The sprinklers are pretty tricky. It’s possible to increase damage via evaporative cooling if windy, dew points are low, and water application inadequate. The ice itself provides no protection. It’s the heat released when water freezes that can hold temp above damaging levels.
You can tell as soon as the ice melts and things dry out a little how many survived.
Wow…yeah…who knows…i probably would have done without the sprinklers. Should have some old sets (non led) Christmas lights for occasions like this? Might not save them all, but maybe enough for a decent crop.
Fruitnut we had little to no wind and low humidity last night so hopefully the ice helped. It probably does not help that my peach trees are near the bottom of a hill and may be in a cold pocket. I was thinking about using christmas lights but my wife informed me that most of the newer type lights do not put off heat due to possible fire hazards. I had a very similar late freeze last spring and lost my entire peach and plum crop so I was pretty desperate to try something and figured if I was going down, that I would go down swinging.
Let us know if you think it helped and how much fruit is left.
I’m formulating plans to protect my Robada and Orangered apricots. They both have a good set outdoors, much better than in the greenhouse but that’s another story. My plan will involve tarps and heat. Around here it’s usually too dry and windy for sprinklers.
I used tarps last night on my pluots and it didn’t help at all.
I lost my whole crop and plums too, but the peaches survived
without any protection. This global warming crap is just that.
Where I live, it’s actually global cooling, not warming. Our
winters seem to last longer and longer. I’ve NEVER had a
freeze this late.
Ray, sorry to hear that!! I’ve found that a tarp without heat inside doesn’t help. My greenhouse doesn’t help much and it’s got two layers of inflated woven poly. That poly retains some IR radiation. This time of yr it’s at it’s best because I’m letting it warm to 80s by day. That provides at most 3-4F protection by morning. In winter it’s same inside as out by morning unless heated.
Fruitnut, after the ice melted there were a good amount of flowers at petal fall stage still on the peach trees. Does that mean the fruit buds likely survived the freeze?
You can tell which survived by cutting open or looking at the little fruitlet. If brown inside it’s dead. After a day or two the dead ones shrivel up. The big difference in hardiness is open vs closed flowers. Anything not yet opened should survive 26 easily.
Chris,
Sprinklers are a recognized method of protecting flowers from a damaging freeze event, but one thing to note is that the sprinklers should remain on, until temps are several degrees above freezing.
The reason for this is because, as Fruitnut mentioned, the ice provides no protection. What provides the protection is that when water changes phases from liquid to solid (i.e. ice forms) energy is actually released. For example, when you make ice cream in a “crank” style ice cream freezer, as the ice cream starts to solidify in the can, it releases heat into the outer ice (which in combination with the salt, actually melts the ice) which is why you have to keep adding ice.
When the ice continually forms on you peach trees, it continues releasing heat into the peach wood and flowers, which can protect them from cold damage.
However, the reverse is also true. As the ice melts, it absorbs heat from its environment. If the sprinklers are shut off too soon (like in the morning) the melting ice will draw heat out of the wood and flowers, making them colder than the outside temperature. That is why it is recommended to leave the sprinklers running until the temps are several degrees above freezing. Any melting ice will draw energy from the running water, rather than the wood/flowers.
2 Likes
Fruit how do you put heat inside of a tarp without melting the tarp or
burning the tree?
I use an electric heater, heat lamp, or light bulb depending on amount of heat needed. Have never burnt anything. With heat lamp in particular needs to be carefully placed. Usually pointed up near bottom of the tree. Pointed down near top might be better but that is harder to support.
The fact that ice formation releases heat just doesn’t seem right. Here’s the way I think about it that makes sense. We all know that it takes a lot of heat input to melt ice. So the same amount of heat has to be released when ice forms. We don’t notice the heat released because it’s so cold when ice forms.
Ray, I use C9 Christmas tree lights and tarp on my citrus and that works well. The new led lights are energy efficient and don’t produce any heat. You can find old used ones on ebay. They are a pain to put up so I switched to overhead irrigation this year but ended up doing more damage because of evaporation due to high winds. Water evaporating causes 7x more cold than freezing causes heat so it is easy to make things worse in the wrong conditions.
How low did your temp go? I actually have a few pluots on my tree this year and I think they are ok, we got down to 33 degrees.
It got down to 28 here and lasted for 4-5 hours. If this happens again next
year, I’m just going to chance it. I think I did more harm than good with
the tarp, and running that many heaters and or heat lamps just isn’t practical.
I use surplus cargo parachutes to protect my citrus trees. They are available from surplus outlets in various sizes. I believe the size is given as radius and not circumference, do keep that in mind. one I use on a pretty big orange tree is a breeze to handle with 2 people and long poles or 2x2’s. I can do it by myself, but it’s a little trickier. I water well under and around the trees and put buckets of water underneath. That has been sufficient in most cases for our area. I think it got down to about 19 degrees above once and got some leaf damage where they touched the fabric.The durability and ease of handling make them well worth while. However, I don’t know what their heat retention would be in sub zero temps.
Ice does indeed release heat as it freezes. 1.1 kcal per mole. There. That’s the extent of my retained knowledge from high school chemistry.
I’ve seen people on the old garden web talk up pool covers. Won’t need it this year, but that might be doable for some smaller trees.
Has anyone here ever tried KDL from Agro-K?
http://agro-k.com/news/kdl-frost/
When sprayed on 36 hrs before it can provide 5-6 degrees protection. I would like to hear some first hand experience and I’m also curious how much it costs.
Agro-K’s Potassium Dextro-Lac®, a foliar macronutrient, is derived from potassium carbonate.
The link above includes a testimonial from Bob Purvis, it sounds promising.
Thanks for the link to KDL, its a little pricey as expected but its great to have another option for freeze protection. As a follow up to my original post, running the sprinklers from midnight to 8am seemed to pretty much work. The trees that were covered with ice seem to have survived with around 10 to 20% fruit bud loss and the trees that did not get the ice protection seemed to have suffered about 80 to 100% % fruit bud loss. My plum trees that are also around the petal fall stage were not watered and are pretty much toast for the season, near a total fruit but loss.
Based on fruitnut’s comments, it sounds like the conditions were favorable for protection via the sprinklers - there was low wind, low humidity and the trees were getting hit with water about every 3 or 4 seconds.
Looks like I may get peaches this year after all, yippee!!!
1 Like
Good to hear you still have a crop!!
Low humidity isn’t favorable for using the sprinklers. Combined with wind it will increase evaporation which sucks away heat.
I just called Agripro and KDL is only $24/gallon, and you apply 3 oz/gallon
of spray. They will ship it directly from their plant in Minnesota, and it will
last 5 years in storage. I will definitely buy some next year. The heck with
using tarps and heaters. Idahomeboy thanks for the info.