Category Archives: Pecans

Pecan Budbreak & Cold Weather

It’s been about two weeks since we observes some budbreak in young pecan trees. We had a day of rain across much of the county this week, and it then dropped to 31 degrees Thursday morning. The picture above is an orchard with frost on the ground. What will happen to our trees now? UGA Extension Horticulturalist Dr. Lenny Wells has this to say:

Those areas with forecasts for 30 degrees or more should be ok. Other areas (North GA) that reach temperatures of 28 degrees or less could see damage to any foliage that may already be out. Fortunately, there is very little of this. I have seen and heard of a little sporadic budbreak here and there—mostly on newly planted or very young trees. Those on which the outer scale has split – and you only see a little green peeking through or the buds are just swollen – should be ok. But, any new growth that has started to lengthen and expand will be most susceptible if temperatures stay at 28 degrees or less for a few hours.

Most mature trees still have buds closed or are barely showing some green (most of this is deep into south Georgia). Those trees on which the buds are still closed should be fine. The level of damage a tree receives in this type of situation is completely dependent upon its level of dormancy.

March 3rd, 2017 – Photo by Mat Thompson

Developing foliage exposed to 28 degrees or less for several hours (usually 3 hours or more) will be burnt off by the freeze. The trees will bud out again, but that will probably wipe out any crop on a mature tree for the year. Since there are not many trees out this far yet, we should be ok. Even those on which we see budbreak only have a small percentage of the shoots breaking bud, so this will help.

The biggest danger will come in the form of cold injury, mostly to younger trees. This damage is usually expressed as longitudinal bark splitting, separation of bark from wood, and sunken areas on trunks, browning of the cambium (the normally bright green tissue normally observed just under the surface of the bark when scraping with a pocket knife), and sparse canopy development. Much of this may not be readily obvious until temperatures heat up in May/June and the water demand increases. The freezing temperatures destroy the cambium cells and the tree then can’t get the water and nutrients it needs. Sometimes the trees may have enough healthy tissue to keep it going for a year or more before it collapses. The more dormant the tree is, the less susceptible it will be. If the sap is rising, there is a risk for cold injury. Trees in low elevation areas will be most susceptible. Any damaged trees will then become more attractive and susceptible to ambrosia beetles, so be vigilant for these as well.

Young Elliot – Photo by Mat Thompson

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Warm Winter And Pecans

UGA Extension Pecan Specialist Dr. Lenny Wells has an update on pecans:

We haven’t had much of a winter this year. We’ve only had 4 days where temperatures dipped below freezing in Tifton and the average temperature since November has been 57 degrees as opposed to 55 degrees last winter. We’ve also accumulated only 368 chill hours as opposed to the 559 chill hours we had by this time last year.

Nursery tree leafing out on 2/21/17 - Photo by Dr. Lenny Wells

Nursery tree leafing out on 2/21/17 – Photo by Dr. Lenny Wells

For many fruit trees, once buds have entered dormancy, they will be tolerant to temperatures below freezing and will not grow in response to mid-winter warm spells. These buds remain dormant until they have accumulated sufficient chilling units (CU) of cold weather. When enough chilling accumulates, the buds are ready to grow in response to warm temperatures. As long as there have been enough CUs the flower and leaf buds develop normally. If the buds do not receive sufficient chilling temperatures during winter to completely release dormancy, trees will develop various physiological symptoms associated with insufficient chilling.

Its really not clear how many chill hours pecans need, probably because there is so much variation from one variety to the next. It is reported that 300 -500 chill hours are required for Desirable, Mahan, Success, and Schley, while Stuart reportedly requires from 600-1000 (I think that’s a little high, myself). Interestingly, Terminal buds have lower chill requirements than lateral buds. So, after a cold winter you may have heavier crop loads because more lateral buds flower and get pollinated at the right time.

In general, pecans don’t need a lot of chill hours. At the southern end of its range in Mexico, you can have trees that receive less than 100 chill hours, and still produce nuts. The actual chilling requirement for pecans also varies with fall temperatures. If trees are exposed to cooler fall temps (less than 34 degrees F) the intensity of the bud’s rest is greater and the number of chill hours required for budbreak increases.   But, the colder the winter, the fewer the heat units in spring required to start budbreak. Heat units in spring strongly influence budbreak and drive the progression of the crop’s maturity. So, with a cold winter and warm spring you can actually get a pretty early budbreak.

We had a warm fall, therefore the intensity of the bud’s rest is weak and the number of winter chill hours required for budbreak will be lower. Indeed if you look around at the edges of fields and in the woods you will see red maples, red buds, and oaks budding out. Azaleas are blooming in the yards. And yes, some pecans are even budding out already as you can see from the pictures above. Unless we have a cool spell to slow things down I expect to see a lot of buds breaking within 2 weeks. What will this mean for the crop?

Well, the main thing is we have to hope and pray for a warm spring with no late freeze. Any late freeze down into the 20’s for any significant length of time after the shoots begin expanding, putting on catkins and female flowers will cause serious problems. The tissue would be burnt off by the freeze. The trees would shoot back out, and grow. We would lose that flower crop and some varieties would try to put on more flowers but most of those secondary flowers either wouldn’t develop into nuts or the nuts would be of very poor quality (because pollination would be off).

Beyond a late freeze, the most likely problem will be poor pollination. Because budbreak tends to be so sporadic, staggered, and non-uniform when you have low chill hours, the synchronization of female flowers with male flowers from the pollinators is usually off, leading to poor nut set and poor quality. The more cold snaps we have from here on out, the more non-uniform budbreak and flower development will be. So, from this point on we need it to stay warm.

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2017 Pecan Spray Guides

2017pecansprayguideUGA Pecan Specialists Dr. Lenny Wells and Jason Brock gave their first of the season program for us in Thomasville yesterday. Dr. Wells updated us on hedging, spacing, and storm damaged trees. Mr. Brock talked to us about our fungicides and resistance issues.

Dr. Wells announced the newest pecan spray guides are now in. Lenny will not have them printed this year, but if you need us to print one for you, we can do that at the office.

Here is the link to the 2017 Commercial Pecan Spray Guide.

UGA Extension Specialist Dr. Lenny Wells presents at the 2017 Pecan Production Update

UGA Extension Specialist Dr. Lenny Wells presents at the 2017 Pecan Production Update

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Ambrosia Beetles: First Flight

Cook County Ag Agent, Tucker Price, called me this week to report seeing the first flight of ambrosia beetles. For us in deep South GA, the first flight is usually late February. UGA Extension Pecan Horticulturalist Dr. Lenny Wells has this information:

Ambrosia Beetle - Photo by Dr. Lenny Wells

Ambrosia Beetle – Photo by Dr. Lenny Wells

We’ve had reports of ambrosia beetles attacking young trees in south GA recently. This is no surprise with the very dry late summer/fall and very mild winter we’ve had.  The severe weather lately will likely make trees more vulnerable than usual where flooding rains and wind have really stressed some orchards. Trees that stand in water for long periods, especially when they are breaking bud and trying to leaf out, are very attractive to the beetles.  Growers should be checking young trees regularly for frass toothpicks that indicate ambrosia beetle attack. It is also a good idea to have some traps out around those young orchards so you will know when the beetles are active. Cold weather will slow or stop the beetle flight temporarily, but we can probably expect to see activity pick back up as soon as warmer temperatures return. See link here for description of management.

Anyone planning to plant trees this year should try to get the trees in the ground no later than mid-February to aid in recovery from transplant shock before budbreak and warm weather arrives. Trees planted late become more stressed and have a harder time recovering from transplant shock.

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Pecan Pruning Clinic – Brooks County

YoungPecans (3)The Brooks County office is going to host a pecan pruning clinic on Thursday, January 19th beginning at 10:00 am. The meeting will cover information related to the pruning of young pecan trees and planting demonstrations.

Dr. Lenny Wells, UGA Pecan specialist will be demonstrating pruning techniques and available to answer questions related to pecan planting &/or production. For additional references & resource, they will have educational material related to program topics.

Location

This meeting will be held in orchard at Mr. Jim Loar’s orchard, 1677 Adel Highway (Hwy. 76), Quitman.  This meeting is sponsored by Cool Planet and will end with lunch at noon.  So that we may plan for program and meal, please RSVP to our office (229-263-4103) by Tuesday, January 17th.

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Will Stuarts Open?

A big concern right now for pecan growers is the delay in ‘Stuart’ shuck split. UGA Extension Pecan Specialist Dr. Lenny Wells has answered calls on this subject. He says, for the most part, they will. The delay in Stuart shuck split should not really come as a surprise. Stuart always has a prolonged shuck split. Stuarts never all open at once as they do for some varieties.

Pecans-ShuckSplit 003Dr. Wells says this characteristic of Stuart is well documented. Dr. Darrell Sparks’ 1992 book, Pecan Cultivars has this to say regarding Stuart shuck split: “”.

It should be no surprise that not all Stuart nuts are still not open. A couple of things have made this seem like a greater problem than normal:

  1.  This year’s nut maturity has been running behind last year’s all season and many growers have been anxious and under the gun to fill mid-November contract orders due to the early Chinese New Year. This has led to many growers shaking Stuarts before they were really ready. Obviously in that situation you only get a few nuts down and especially on the first early shake you get a lot of green nuts out. Many growers have shaken Stuarts twice already and because the shuck split is so drawn out they get the same results on the second shake and this generates alarm but I believe the rest of these nuts will open, although obviously not for mid November contracts.
  2. We are in a severe drought. Many areas of Georgia’s pecan belt have had no rain since early September. Even with irrigation this has delayed shuck split on Stuart even more. Also, many growers turned their irrigation systems off too early or never turned them back on after harvesting individual orchards for the first time. With a heavy crop load, this will create additional stress and you will see a further delay in shuck split, sprouting, and shuck decline or stick-tights. Trees at the extreme of this situation will likely have nuts that may not open but the only real chance to get them open (outside of a good rain) is to turn the irrigation back on. It sounds crazy for us in the SE to irrigate pecans into November but when it is this dry it becomes necessary. You don’t have to water much but irrigate for 4-6 hours a couple of times a week—or every other day if you have trees in the situation described above.

Don’t expect to get all of your Stuart crop in until at least December or until we have a good rain and/or some cold weather. I think if growers look back at their records they will see that, for the most part, this is normally the case.

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2016 Pecan Market Prices & Harvest Update

We have some very good reports of pecan grades coming in from last week, at least in Pawnee’s and nuts which have been harvested. Click this link to check Current Pecan Market Price. You take the price per point and multiply by the kernel percentage to get price. They are updated throughout the season at this link. UGA Extension Pecan Specialist Dr. Lenny Wells gave us this update today:

The pecan harvest picked up momentum this week as many growers began harvesting Desirable, Stuart, and other mid-harvest season varieties. Desirables seem to be shaking out well while Stuart is probably not quite ready to really come out as we would like. I expect they won’t really shake well in most orchards for another couple of weeks. However, many growers with mid-November contracts are now under the gun and have to proceed and sacrifice a few green nuts to meet their contracts. Growers in East Georgia are still dealing with cleanup from the last storm and are trying to harvest around the debris in some cases. Prices remain very strong.

The most common question I have regards the drought throughout most of the state, not impacted by the Hurricane. Most of these areas have not seen rain since early September, and conditions are terribly dry. It makes for good harvest weather, but many growers are concerned about the tree’s water needs at this time. For mature trees, Continue irrigation at about 40% until shuck split is advanced enough to shake, then turn irrigation off 4-5 days prior to shaking to allow shucks to dry. My observation has been that this helps them to shake out better. After going over the orchard, turn water back on for about 6-8 hours a couple of times a week until we get a 1″ rain.

In many cases, hot weather like we are seeing puts some varieties that tend to spread out their shuck split, like Stuart, at risk for sprouting. So, that is a possibility under our current conditions.

Immature trees may benefit from irrigation once a week for 4-5 hours until rain arrives or until they lose their leaves. Don’t over-water young trees at this time of year because you don’t want to delay them going into dormancy and put them at a greater risk for cold damage when the cold weather arrives.

We do have a newly published extension bulletin on Pecan Water Requirements and Irrigation Scheduling. This is for mature trees only.

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