Wednesday, October 18, 2017

That one pecan that doesn't open

   Over the past several weeks I've be photographing pecan shuck-split and collecting nut samples. If you look at enough nut clusters like I do, you will usually come across a cluster that has one nut that doesn't seem to split at the same time as all the others (yellow arrow, photo at right). In fact, the shuck stays green and tight all the way until first Fall freeze and never opens. Whats going on here?

   The cluster pictured above yielded four nuts (photo at left). Three of the nuts were easily removed from split shucks. The forth was tightly held inside a green shuck. 

    I cut each nut in half to inspect the kernel within (photo at left). The three normal pecans were fully packed with kernel. The nut with the tight green shuck had the remnants of a kernel that stopped growing at the water stage (early August). Judging from the color of the unfilled seed coat, this kernel was aborted by the tree for some unknown physiological reason.  If the seed coat had been colored jet black, the nut would have been the victim of stinkbug feeding. If the nut had been hollowed out by pecan weevil, I would have found worms inside the green stick-tight. In each case, lack of kernel fill prevents the pecan shuck from opening properly.

Tuesday, October 17, 2017

Pecan germination in the shuck

   Vivipary: A ten dollar word that describes the premature germination of a pecan in the shuck during the Fall of the year.  Normally, pecan seeds are fully dormant in October and require a 90-day chilling period to stimulate germination. However, a heavy nut crop and unusually warm, moist, weather conditions during shucksplit can trigger vivipary. In the photo at right, the yellow arrow points to a pecan root emerging from a recently harvested pecan. When a sprouted pecan is harvested and dried under normal harvest conditions, the little root dies and the embryo inside the shell decays. Ultimately, embryo rot totally destroys the value of the kernel.
    Fortunately vivipary is a rather rare phenomenon in northern pecan areas. This year I've found only 2 sprouted nuts among the thousand of nuts I've collected for evaluation this winter. Most years I never see vivipary at all.

Monday, October 16, 2017

Pecan cultivars ripening by Oct 16

Lakota, 16 Oct. 2017
   Today, I took another tour of the grove to look for ripe pecans and enjoy the crisp Fall air and beautiful sunshine. I found five more pecan cultivars with split shucks (at right and below). This year, Giles and Lakota appear to be ripening a little later than normal while Caddo and Maramec have split earlier than normal. Caddo definately appears to have a scab problem even after 3 fungicide applications. Lakota is scab resisitant. The good news is that our spray program gave acceptible scab control on Giles, Maramec, and Mohawk.
Giles, 16 Oct 2017
Caddo, 16 Oct 2017
Maramec, 16 Oct. 2017
Mohawk, 16 Oct 2017

Tuesday, October 10, 2017

Pecan cultivars ripening in early October

Kanza, 7 Oct. 2017
    This week I found 7 more cultivars with split shucks. Many of these cultivars are scab resistant including; Kanza, Greenriver, Hark, Oswego, and USDA 64-4-2. It is so nice to find pecans with clean healthy shucks at the end of the season. In addition, our disease prevention spray program did a pretty good job on limiting the spread of scab on disease susceptible cultivars, Chetopa and Niblack.

Chetopa, 9 Oct. 2017
Greenriver, 9 Oct 2017
Hark, 7 Oct. 2017
Niblack, 9 Oct 2017
Oswego, 9 Oct. 2017
USDA 64-4-2, 9 Oct 2017

Monday, October 9, 2017

Time for Fall fertilization

    If you can believe the National Weather Service we have a 80% chance of receiving a light Fall shower tonight. So today, I thought it wold be the perfect time to make our annual fall fertilizer application (photo above). We spread 100 lbs of urea per acre using conventional fertilizer spreading equipment. With this urea application, we added 46 lbs of nitrogen to each acre of pecan trees.
    As pecan trees prepare to move into winter dormancy, they produce a flush of new root growth. These actively growing roots aggressively take up the added nitrogen and store it in woody tissues to be mobilized next spring. With a ready supply of nitrogen, the tree will make vigorous new shoots and ample pistillate flowers next year.
   We have been making a Fall fertilizer application in addition to the regular Spring application for over a decade and have seen an overall increase in nut production and a decrease in alternate bearing.

Monday, October 2, 2017

Pecan cultivar shuck-split: October 2, 2017

Faith, 2 Oct. 2017
    The weather man is predicting an extended wet period starting in a couple of days. So today, I thought it would be a good idea to take advantage of the sunshine and check pecan cultivars for shuck-split. I found 13 cultivars with newly split shucks (photos at right and below).  As you look over the photos, keep these observations in mind.
Gardner, 2 Oct. 2017
 1) Peruque and USDA 75-8-9 should have shuck split last week but serious scab infections delayed shuck opening. Both cultivars are almost completely black with scab lesions.
 2) I couldn't resist taking a photo of a very large Pawnee nut cluster. There are 9 nuts in the photo below. The average Pawnee nut cluster has 4 pecans this year.
Pawnee, 2 Oct. 2017
 3) Jayhawk has a very heavy nut set this year. The photo below shows 3 Jayhawk clusters all hanging from a single limb. With this much nut set in 2017, the 2018 Jayhawk crop will be light or non-existent.

Jayhawk, 2 Oct. 2017
Eclipse, 2 Oct. 2017
Major, 2 Oct 2017

Mandan, 2 Oct. 2017
Peruque, 2 Oct. 2017

USDA 61-1-15, 2 Oct 2017

USDA 61-1-X, 2 Oct. 2017
USDA 75-8-9, 2 Oct. 2017
Waccamaw, 2 Oct. 2017
Yates 68, 2 Oct. 2017

Thursday, September 28, 2017

Pecan cultivars that split shucks in late September

Osage, 28 Sept. 2017
   I spent a sunny afternoon looking over our pecan crop and photographing pecan cultivars that have split open their shucks since last week. I found 12 cultivars fully ripe (photo as right and below).
    As you look over the photos you can spot the cultivars that are susceptible to pecan scab. The 12 pecan cultivars that ripened this week can be broken down into three categories when it comes to pecan scab; resistant, susceptible but clean, and susceptible with scab lesions. The "susceptible but clean" cultivars are mildly susceptible to scab allowing our fungicide spray program to completely control the disease. The "susceptible with scab lesions" have a greater degree of susceptibility to scab infection and our spray program did not provide perfect control. Below is a list of the cultivars that ripened this week divided into the three scab susceptibility categories.

Resistant:   Norton, Osage, Shepherd

Susceptible but clean:  City Park, James, Posey, Surecrop, USDA 75-8-5

Susceptible with scab lesions: Canton, Colby, Witte, USDA 64-11-17

Norton, 28 Sept. 2017

James, 28 Sept. 2017

Colby, 28 Sept. 2017
City Park, 28 Sept. 2017

Canton, 28 Sept. 2017

Posey, 28 Sept. 2017

Shepherd, 28 Oct. 2017
Surecrop, 28 Sept. 2017

Witte, 28 Sept. 2017

USDA 64-11-17, 28 Sept. 2017

USDA 75-8-5, 28 Sept. 2017

Tuesday, September 26, 2017

More early ripening pecans split shuck

KT143 (Pawnee x Major)
    Yesterday, I spent the day in a hydraulic lift evaluating the nuts of pecan trees in our pecan breeding trial. I found 14 pecan hybrids that had split shuck since my last trip thru the orchard (Sept. 20)  As I traveled down the row of pecan crosses, I came to tree KT143. This tree has a special place in the history of our pecan breeding project. KT143 was the very first tree in the planting to start bearing pecans and has produced a crop every year since. KT143 is the result of a cross between Pawnee and Major. The nut appears to be scab resistant and the shucks opened before either parent this year (photo above).

    Of course, its whats inside the shell that counts when evaluating pecan hybrids. My records from previous years tell me that KT143 averages 7.52 g/nut and produces 54.8% kernel. From a practical point of view, I measured the 2017 crop and found it would drop out of a pecan sizer as a number 15 (15/16 inch).  As you can see from the photo above, the kernels have wide dorsal grooves meaning the kernels will drop free of all shell fragments when cracked. We currently have this clone under advanced testing in a new planting at the Pecan Experiment Field.

Thursday, September 21, 2017

Early ripening pecan cultivars split shucks

   Yesterday, I found that the earliest ripening cross in our pecan breeding plot had split shuck. So today, I inspected all of our pecan cultivar trials at the Pecan Experiment Field to discover which early ripening pecans had split shucks.
Henning, 21 Sept. 2017
   I found three pecan cultivars with split shucks (photos at right and below). Henning and Mullahy are northern pecan cultivars first discovered as native trees. SWB617 is a chance Giles seedling we have at the research station. I expected Warren 346 be be ripe at this time but our trees of this cultivar do not have a nut crop this year.
Mullahy, 21 Sept. 2017

SWB617, 21 Sept. 2017

Wednesday, September 20, 2017

First pecan to shuck-split

   I spent some time today looking at trees in our pecan breeding plot. I was especially interested to see if our earliest ripening hybrid had split their shucks yet. Using our hydraulic lift, I climbed up into the canopy of the tree to find limbs loaded with fully ripen pecans (photo at right). This is a tree labeled as KT337, a cross between Pawnee and Greenriver. So far, this tree has demonstrated good scab resistance and is bearing annually.

   The nuts of KT337 are small in comparison to many modern pecan cultivars but are large enough to produce very attractive kernels (photo above).  The few nuts I pulled from the tree averaged 13/16 inch in diameter (21mm) and were 1.5 inches long (38mm).  The kernel was well packed inside the shell and the dorsal grooves were wide and "v" shaped (indicating the nut meat will fall free from all shell and packing material). I'll be keeping my eye on this one.

    To give you a better idea about nut size, I collected a few Pawnee nuts and peeled the nuts out of the shuck (Pawnee has not split shuck yet that's why the shell color is white). The photo above gives you a good visual reference as to the size of KT337.  The nuts are obviously smaller than Pawnee but not  unacceptably small.