Thanks for that explanation.

Does this only work on still air nights when the danger of frost is greatest?

I would think that with wind the inversion could not happen is that correct?

Wind machines are only beneficial during a radiational freeze where there is a thermal gradient over an orchard. However, I would think many growers now rely more on water spraying systems such as Stan has installed in his orchard, at least for the smaller sized trees. Millet (774-)

I'll be impressed if someone can identify the rootstock by looking at those pictures. can it be determined what type without any leaves?

gdbanks,

I will be VERY impressed indeed! There are (obviously) no suckers and never been any...

Thank you!

Actually, it looks like the tree came through the cold spell in pretty great shape. I doubt that the tree in the picture will have any trouble. - Millet (771-)

Millet,

thank you very much! Actually, it really seems so. The last flush is likely do die and leaves are falling... Some older leaves have signs of injury as well. I really hope the plant will not get more damage.

I agree with Millet.

The rootstock is Poncirus.
We have a guru on the french forum who knows how to recognize the rootstocks and is teaching us how to do.
Some are very easy:
- Bitter orange: nearly black
- Poncirus: light grey keeping a long time green stripes
- Macrophylla: very rough surface.
For others, I am still learning...

Our guru has also built a way to determine any Citrus by the taste of the leaves. Very interesting but needs a long training.

I stipped by a couple of days ago and there is no way to tell if the root stock is Trifoliata or one of the hybrids. Could be Carrizo or Swingle. The nursery it came from propagates on several different root stocks.

Some nurseries, W&N for example, use different stripes of color paint for each kind of stock that is used. I think this system is helpful in later determining what stock the tree is grafted upon. I agree with both Bonnie and Sylvain, in that the stock looks to be some form of Poncirus, but whether it is a pure stock, or a hybrid, who knows except the nursery that grew it. Most of the time a simple telephone call to the nursery clears up the situation. - Millet (770-)

I asked our guru. I am pretty sure he can differentiate PT, Swingle and Carrizo.

Sylvain, Bonnie,

thank you very-Very much! This is so impressive that you can differentiate rootstock types just by looking at a picture!!! Guess, I will hope that the roots are trifoliata and will be more cautious in the future. Thank you for the excellent suggestion, Millet!

If it was Saxon and Becnel from there, it is citrange rootstock. Shakleford at Brazos uses trifoliate as well as other rootstocks.

The sure way to tell is to let a shoot from below the graft grow out a few inches.

MrTexas,

yes, the plant came from Brazos Citrus Nursery... http://www.brazoscitrusnursery.com/

Thank you!