Freeze Watches/Warnings

Freezing cold weather is set to wash over the state of Florida tonight into tomorrow night, so please be prepared!

A few comments about freeze protection in orchards:

  1. Be sure that your orchard is well-watered – we will be getting sun each day, and wet soil has a greater capacity to absorb heat, and also release it during the night, offering a few degrees of protection.
  2. Watch the weather – and keep your coffee pot going.  For those in Central Florida and to the south, it looks like the temperature will drop to a critical period around 2 a.m. on Friday morning.  However, if the wind is too high, you may induce evaporative cooling rather than protect the fruit, which can do more severe damage.
  3. Know what your irrigation system capabilities are to be able to meet the appropriate water output.
    1. See: http://edis.ifas.ufl.edu/ch182 – this is for citrus, but the principles that they go over, like reading a sling psychrometer are useful to understand.
  4. Hold off on any orchard related activities, like thinning fruit – the cold weather may do a good job of that for you!

Weather Related Resources:

  • The National Weather Service – http://www.noaa.gov/ – just put in your city or zip.  I find that the best resource is a graph like this which gives you the temperature and wind speed which is important:

CitraNOAA_2-20

 

 

 

 

 

 

 

 

For those of you that might be stressed – have heart!  It won’t be as cold as it will be in Citra, FL at our research plots for peaches and blueberries!

As always, if you have any questions, please contact me – mercy1@ufl.edu.

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Cold Weather Knocking on the Door…

I hope that everyone had a FANTASTIC Christmas vacation (ala Clark Kent style) and is having a great start to their new year.  As we start off this new year, cold weather comes knocking on our door in north central Florida, a normal occurrence.

Freeze warnings/wind chill advisories (1/7/15)

There maybe some of you in north central Florida that are closely watching the weather tonight.  For the following counties, there is a hard freeze warning:

  • Alachua
  • Gilchrist
  • Bradford
  • Union
  • Baker
  • Columbia
  • Suwannee
  • Hamilton

The good news is that hopefully, the peach trees are still resting are not in full bloom.  For a guide to bud stages and their tolerance to cold temperatures – click here.

For counties to the south and east, it’s a freeze warning:

  • Clay
  • Putnum
  • Marion

Again – I don’t think it’s anything to be concerned about unless the wind speed drops down.  However, NOAA is forecasting a blustery night with wind speeds sustained at over 15 mph.  In most cases, frost protection would not be turned on with these advective conditions.   Most all others in the peach growing region of Central Florida will have mid to upper 30s so stay warm!

 

Freeze Warning and Watches

Well, here we go with the rollercoaster of temperatures in central and south central Florida. So what is going on with the peach trees right now?

Don’t worry!  The peach trees are headed into dormancy, and although the buds have the possibility of suffering a minor amount of damage (<10%), we don’t anticipate any major issues with flower bud damage.  There is NO need to turn on irrigation for frost protection tonight and it is expected to warm slightly tomorrow night, so no frost protection for the next night as well.

The UF Stone Fruit Research/Extension team has a new project in cooperation with Georgia (UGA) for both blueberries and peaches and we will be tracking bud damage as a result of the expected freeze event tonight at our research plots in Citra, FL.  We be looking at flower buds in TropicBeauty peach and Emerald and Jewel blueberry varieties.  When we have the information, we will be posting it here on the blog, as well as on our website, http://hos.ufl.edu/extension/stonefruit.

Freeze Watch/Warning Information:

For a list of current freeze warnings and watches:  http://alerts.weather.gov/cap/fl.php?x=1.

11-18-14

Another Round of Cold Weather!

In January and early February, we all deal with the waves of cold fronts that dip down from the Canadian Arctic.  However, as many growers are in full swing with bloom or have just started, these cold waves keep us all up at night.

At Citra in one of our plots that has some bloom occurring, we have turned on the water on the following dates:

  • Tuesday, January 7th
  • Friday, January 17th
  • Saturday, January 18th
  • Sunday, January 19th
  • Wednesday, January 22nd

We will continue to monitor tonight (Friday, January 24th) for cold weather, since it looks like the wind will be dying down.  The graph below details the actual temperatures for the Gainesville Regional Airport (KGNV) which is a few degrees colder than what we observe in our research plots at Citra.

This graph shows the minimum temperatures for January for Citra – and you can find out this type of information for a FAWN station near you with this link: http://agroclimate.org/tools/climate-risk/.

2014 Citra Minimums

Tools

What are some tools that you can use to help decide when to turn the water on?  One thing I can offer – the wind will almost always kick the temperature up a degree, so be on the lookout and carry a good thermometer with you as you are driving around the orchard.  Your car thermometer may not be the most accurate, so don’t count on that.

Good luck tonight, and stay warm!

Mother Nature Strikes with a Freezing Touch

March 1, 2012

Well, this year has been a tough one already for those in Northern and North Central Florida in the peach business.  On the night of February 12th, our orchard at the Plant Sciences Research and Education Unit in Citra, FL experienced an advective freeze.  Remember those?  We haven’t had a windy freeze in a while – definitely in over 3 years.  The final temperature was about 25°F, with steady 15 mph gusts.  The water was turned on about 3 am, as a break came in the wind; however the wind picked back up in the morning, effectively destroying any protection that we tried to put out with our ice loads.

We had pretty good ice formation, with much of our wood covered in ice.  Our irrigation for frost protection is set up on 20 x 20 spacing with 8 foot PVC pipes and brass impact overhead sprinklers.

A few heartbreaking pictures:

Freeze Damage, Citra, FL
February, 2012

These were ‘Flordaprince’ on the left, and ‘UFSun’ on the right.  The only difference is that the ‘Flordaprince’ was pruned, while the ‘UFSun’ had not been pruned .  This resulted in severe limb breakage, with some of the trees only having one remaining scaffold.  We  had to pull two younger ‘UFSun’ trees.

After the ice melted off, we noticed that many of the flower petals were brown and freeze damaged; even the flowers that were at a “pink bud” stage had started to brown.  When we cut through the flower, the pistil on many of these flowers were dead.

As the picture shows, during the night we had enough ice formation to fully encase the flowers and the buds – and the ice was fairly clear, meaning that the ice formed quickly without any air bubbles.  Air bubbles could potentially affect the insulation factor of the ice, and reduce the effectiveness of the ice formation.

This tree on the left ended up with some of the ice that had air bubbles in it, but the full effect of the ice formation was hampered by the steady winds over 10 mph, gusting to 15 mph throughout the night.

About five days after the freeze, I went through to check what fruit was alive or dead.  Fruit where the embryo was alive were green throughout, with a clear pit forming, while those fruit that were dead were brown, including the surrounding pit tissue (see below).  While most of the time our freezes are radiative, we had a one-two punch here in Northern Central Florida, with an advective freeze on the night of the 12th, and a radiative freeze on the night of the 13th.

Viable and Dead Peach Fruit
Alive Fruit (on left), Dead Fruit (on right)

A number of researchers and growers around the country are looking at alternatives to combat these freeze situations, including using tunnels during the frost season and even wind machines.  Although wind machines were once used unsuccessfully in the citrus industry during the major freezes in the 80s, the technology has advanced with better engines, blade design, and greater effective area, reducing the number required per farm.  In addition, the use of a wind machine or other frost protection method like tunnels can reduce the water utlized during freeze events.

Here’s to hoping for a better year next year for our research and breeding program!