Months, evidently; at least the ones near the surface, as the ground has been frozen in a similar manner here in zone 7 many Winters over the years.

I've seen those surface roots in ice for a month or two, and seen no damage to them after the thaw.

Have you seen them survive a deep freeze? One that might freeze the soil to the lowest root level?

We don't have freezes that deep around here, though I doubt it would bother the roots (just my opinion). I say that only because if the smaller feeder roots at the base of the tree (pencil-lead to pencil-size thickness) can withstand extended freezes, I think the larger roots can, too.

As far as root-depth is concerned, I have dug Figs in the beginning of their third year (two complete years inground), and found their "tap" root extending to 4 feet deep--MANY of them; and many others 3 feet and more deep.

How deep were they originally planted? I stuck 100 fig cuttings about 8-10 inches long, 4/5 of their length into the soil in early Spring, 2004, and 80 of them took root. I meant to dig them before they broke dormancy in early Spring, 2005, and pot them, but got called away, and they broke dormancy in my absence. After they broke dormancy in 2005, I decided to wait and dig them in early Spring of 2006 (which I did).

I could not believe the length of the tap root they put down in that period of time (two growing seasons). Needless to say, I had to cut all those "tap" roots to get them out of the ground and into 2' deep pots. Most lived.

I don't believe our soil in zone 7, Maryland, has ever frozen to that depth.

I sometimes wonder whether a pot grown Fig--which has lived in the confines of its container for a period of time--will ever establish such a tap root, if later transplanted into the ground.

I wonder, also, if a long taproot--some part of it always below the freeze line--imparts Winter hardiness to a Fig, as opposed to a more shallow-rooted Fig? Certainly it is more difficult (or impossible) for frozen roots to take up and distribute moisture to the tree (when needed), as opposed to deep roots that are not frozen.

Is this why Fig-growers say the dessicating effects of cold Winter wind is more harmful to Figs than cold, itself--because it removes the moisture from the exposed wood of the tree--and if the roots are also frozen and can't properly react to replace that moisture, the exposed wood surface dies--from dehydration??

My (hypothetical) point, therefore, would be that the most Winter-hardy Figs may be ones never confined to a pot, but allowed to grow straightaway into the ground, from a cutting, where their root structure (and "taproot" length) is never compromised. (Fig growers in cold climates, take note, should my (hyothetical) point have merit.) :-)

I don't know if a fig grown in site would be hardier or not, but the theory certainly sounds reasonable. I have only put previously potted figs in the ground. But they survived winter temperatures way below freezing without any protection. It was much colder around here then - we routinely got down to zero F.
I had planted a row of figs, to get bigger plants (more figs), but found that the area didn't heat up fast enough to get them going in time to ripen the figs. I did get more figs, but none that were edible. So I didn't protect the plants after that first season - they died back, but came up from the roots for a few years until I dug them up.
I don't think you'd have to worry about your figs unless they weren't completely dormant and got a big temperature fluctuation.
How cold did it get, and for how long? What had the temperatures previous to the freeze been like?

Fig roots can withstand THE freezing temp (32*F/0*C) for
'quite' a long time. A more realistic 'question' is what
is the absolute minimum temp, (and for what time?...) I
have heard a minimum as low as 5*F and as high as 20*F...

George, I don't know what absolute minimum would be. I've had potted trees in a garage go to below 15 degrees F, but I don't know how long it lasted.
In the ground, I think the roots would be more protected. I've had them go to at least zero F, for several winters as I said above, and the plants survived.
I'm sure variety is also a factor. I posted some excerpts yesterday from a Southern Fruit Fellowship newsletter, and the Celeste Fig mentioned had gone to zero and one degree F without top dieback! Impressive. It died back to the ground at -5 F, but grew back. Again, I don't know how long the cold lasted.
But I think figs are a lot tougher - when they are deeply dormant - than we generally give them credit for when it comes to surviving cold.

The origin of my question stemmed from reading a paper about Root-Knot Nematodes written by a gentleman from the Univ of Illinois. In my previous research into RKN, I discovered that there are several varieties of RKN (species Meloidogyne). The two that seem most likely to infect fig trees are M. incognita (southern RKN) and M. hapla (northern RKN). In Dr. Babadoost's paper, he indicated that many crops being brought into Illinois might be affected with M. icognita, however the spread and damage is minimal because M. incognita cannot tolerate freezing temperatures. So my thought was to soak bare-rooted trees in iced water for some period of time to kill the little bass turds.

I spoke with Dr. Babadoost earlier this afternoon. He indicated the exposure to cold had to be long-term (months) in order to effectively kill them. In the conversation he also told me that a more effective way of killing them was using a hot-water treatement. The goal is to use water as hot as the tree can tolerate for as long as it can tolerate (I've seen websites indicate anywhere from 110F to 125F for periods ranging from several minutes to hours depending on the plant).

I am assuming since my trees are in Houston, they are infected with M. incognita. I am going to try hot water treatements in Houston and NJ to see how it works. I will also try some in NJ without the hot-water treatment to see how well the cold alone works.

I'll let you guys know how it works next year.
~james

James, Sorry for jumping to conclusions on the root freezing thing.
It's nice to know that if northern growers "buy in" the problem, it will take care of itself in time if the fig trees are allowed to freeze over the winter. Do you know if they would be killed quicker by even colder temperatures?
I saw a couple of references that made the claim that asparagus(plants grown near or juice used to water), or coffee ground mulch killed/repelled RKN.
Don't know if it's true. It seems that "miracle solutions" get hyped, a lot of people use them, and then the research finds they aren't as totally effective as advertised. But you never know. If you enjoy coffee and aspargus it might be worth a try:>)
Good Luck

James: I started my previous post hours ago, then was called away, and just returned to finish it, so it's off-topic regarding Nematodes (those little suckers).

I had someone send me a bare-toot Fig from the deep South, and it appeared to have Nematodes among the roots (little balls looking like Osmocote, attached to roots), also. First time I've had that happen; I isolated the plant out in my barn, while wondering how to cope with something I've rarely seen (in the North or South).

I contemplated dunking the roots in 1%Rotenone solution (in my mind), but don't know whether that would off the little suckers, or not. I'd better read up on the subject, also (or discard the tree I paid for). Be just my luck incognita would breed with hapla, and produce some super-nematodes that would take over the world.

Mojo, That tree sounds like a revolution in fig growing! When does it ripen it's figs?
(I don't think anyone is going mind going off topic on this particular subject!)

Ripens them from July to August. I've marveled at the tree for years, and wondered if anyone else has seen a comparable tree. I've actually stood watching it when the weather was a few degrees below zero F (-19 C) just to see if any green bud-tips (at the ends of branches) were damaged by the cold. None were, and all leafed out in Spring.

Fignut,

M. incognita (southern RKN) is susceptible to the cold. This is a combination of temperature and duration. I assume as the temperature drops the duration probably will decrease as well. M. hapla (and probably others) will survive the cold. The Ontario Ministry of Agriculture indicated that the infestation was worse in 2005 than it was in 2004.

I don't know how well asparagus or coffee work. Leon has posted before that hydrogen peroxide or sugar water may also be effective. UCD indicated 125F for 10 mins is 100% effective in grapes. Other sources seem to support this.

Marylandmojo,

M. incognita seems to be a big problem along the Gulf Coast... something about warmth and humidity that they like. Fortunately, in NJ, I have two properties (separated by 7 miles) to grow on. So when I bring my trees from Houston, they won't be so close to where I am keeping the clean trees and blueberries. RKN is a slow migrating bug without help. Some things that help it move along is wind when digging in RKN infest soil and rain runoff. The biggest factor is people. Dirty soil on the bottom of shoes, equipment, tires, etc. help it move along from one area to another.

One more thing to consider. I remember reading on the forum (I think it was tapla who discussed it) on young fig trees, you can remove a significant portion of the roots and the tree will reproduce them.

Anyway, its getting late. I'm getting tired and I'm rambling. I'll try to proof read this tomorrow. LOL.

~james

Most marigolds are prolific nice flowering annuals with
an additional BONUS of keeping (them nasty) RKN in check...

Here is a link that might be useful: French Marigold Nema-Gone

George from what I've read about Marigolds (and other nematode repelling plants), they don't actually keep RKN away from other plants, they just kill the bugs that enter their own roots. I've attached an article from LSU about this.

"Although planting marigolds as companion plants for susceptible crops sounds like a good idea, it just doesn't work. The nematodes that enter the marigolds are killed but not the ones that enter the susceptible crops. Eventually they will build up on the suitable host and cause problems."

~james

Here is a link that might be useful: lsu article

James,

Yes, marigolds do act as a DEAD-TRAP for them RKNs.

ANYONE,
(forgot WHO!) but mentioned that he/she detected
RKN in a recently bought bare-rooted fig. My advise is
NOT to contaminate your 'garden' even if you bought it
for a $1000 premium price! Ask for a refund, salvage it as
(top) cuttings or just dump in the garbage (not compost).

George (NJ).

Clarification the RKN (marigold) dead-trap:
Mother RKN is not affected. Offsprings lurk around
for new roots hosts. If they enter a marigold root, they
are dead. If they entera fig root (or many others), they
just got lucky, live and reproduce more RKNs...

IÂve been lurking for a while now, lots of good stuff here, thanks for all the info. Happened to notice this in the current Park Seed catalog.

Here is a link that might be useful: Marigold Golden Guardian

George, the idea of not introducing them is a good one on paper, but as I remember reading about the gulf coast (I think it was BigEasyJock who said it) you either have nematodes or you are going to get them. Its quite a significant problem in a hot and humid environment. I have them on all of my figs grown in-ground. Even on the roots of new cuttings grown in a raised bed that is far from the other trees and has not had anything grown in it for many years.

Marigolds may be good for reducing their numbers in the ground when it is the only thing planted. However, the article from LSU indicates it is not a long-term solution nor does it prevent the nematodes from attacking susceptible crops in the vicinity. If my reading is correct, Marigold roots kill nematodes that enter it, but do not actively repel the buggers. Given this and the issue that Marigolds prefer full sun and figs shade most things underneath, I will try them in a pot with a fig known to have RKN and see what kind of results I get next year.

In the mean time, I'm growing my trees in containers and giving up on putting them in the ground.

~james

Your original question was regarding cold-hardiness/tolerance. Commonly, each species of plant has a general range of cold-hardiness, but we know this does not apply to F. carica. Within species and cultivar, cold-hardiness is genetically determined. That is to say that a plant that is propagated from cuttings or tissue culture will have the same ability to resist cold as the parent plant. Plants cannot "develop" a greater degree of cold-hardiness by repeated or prolonged exposure to cold, even after 100 years (trees).
If we pick any plant at random, it may or may not be able to withstand freezing temperatures. The determining factor is the plants ability to prevent freezing of bound water. Bound water is the water inside of cells.

There are actually three kinds of water to consider when we discuss "freezing". The water held in soil - When this water freezes, and it can freeze the soil mass solid, it doesn't necessarily kill the plant or tissues. Then there is free or unbound water, also called inter-cellular water. This is water that is found in plant tissues, but is outside of living cells cells. This water can also freeze solid and not kill the plant. The final type of water is bound water or intra-cellular water. If temperatures drop low enough to freeze this water, the cell/tissue/plant dies. This is the freeze damage that kills plants.

Fortunately, nature has an antifreeze. Even though temperatures drop well below freezing, all plants don't die. In hardy plants, physiological changes occur as temperatures drop. The plant moves solutes (sugars, salts, starches) into cells and moves water out of cells to inter-cellular spaces in tissues. These solutes act as antifreeze, allowing water in cells to remain liquid to sometimes extremely low temperatures. The above is a description of super-cooling in plants. Some plants even take advantage of another process to withstand very low temps called intra-cellular dehydration.

The roots of your trees can stay frozen for extended periods or go through multiple freeze/thaw cycles w/o damage, so long as the temperature does not fall below that required to freeze intra-cellular water. If roots remain frozen, but temperatures remain above killing lows, dessication is the primary concern. If the tree is able to take up water, but temperatures are too low for the tree to grow and make food, stored energy becomes the critical issue. Dormant and quiescent trees are still using energy from their reserves (like a drain on a battery). If those reserves are depleted before the tree can produce photosynthesizing mass, the organism dies.

There are a number of factors that have some affect on the cold-hardiness of individual plants, some of which are length of exposure to seasonal cold, water availability (drought stressed plants are more cold tolerant), how recently planted/repotted, etc.

Al

Morus...the group of related plants which contain figs also contains another relative, mulberries where cold hardiness seems to be on a clone by clone basis as well

There are some mulberries (both alba and supposedly nigra) where the plants hardiness only extends into the upper 20's F. There are other clones which are hardy down to -25F. Pakistan, a morus alba variety can't take much in the way of freezing temperatures it seems, but Illinios Everbearing (another alba) takes temperatures well below zero without losing a bud.

I've got a fig that was due to be destroyed. A friend of my wife was selling her house (here in Mi) and the realtor told her that the property would be more likly to sell if the big overgrown yard was cleared. She had a fig which had never been protected, yet it fruited yearly (I don't know if it died back or not). I dug up a couple pieces (and broke 3 shovels). I didn't take any chances though, I protected it this winter (it spent last winter in a pot as I dug it in Late Oct). The darn thing is 7 feet tall, though.

~Chills

Are mulberries susceptable to root knot nematode? Can fig be grafted onto mulberry?

Mulberries are susceptible to RKN. Apparently they infect a wide variety of crops. Perhaps there is a way to cross Fig DNA with Marigold DNA. LOL

~james (aka Dr. Figenstien)

Yes fig and grapes can be grafted to mulberries.I know that grapes for sure,as my father had a grape grafted to a mulberry,long time ago,and fig i was reading somwhere in the literature that it can be done but i do not have experience with.God bless

I guess this is getting off topic (which is my fault, sorry) but I was hoping that if figs could be grafted to mulberries, and mulberries were resistant to RKN, then maybe there was a potential solution.

SO - an even wierder thought here is that maybe grapes are not susceptable to RKN? Maybe we could graft a fig to a grape? Maybe I should try that.....

Back on topic, more or less, I guess that grafting onto a hardier rootstock would not have an advantage, because the top would be killed by the freeze, just leaving the rootstock?

RKN atacks grape as well.Only a few grape rootstock as SO4,and one more i think is Resistant to it.

eukofios,

You bring up a good topic. Some of the LSU varieties are suppose to be resistant to RKN. Perhaps other varieties can be grafted onto one of these varieties. I can tell you that LSU Purple has one of the more vigorous root system I've seen. I received a small rooted plant last year from George. In one season its roots filled a 2 gallon container and wrapped around a few times to boot.

I don't think I have time right now, but perhaps later this year I will be able to root a bunch of LSU Purple for the roots. I'll let you guys know when they're ready if anyone wants to play around with them.

Should be fun.
~james

marylandmojo - is there any chance that the unusually cold hardy fig tree that you posted about could be provided as cuttings?