Saturday, October 10, 2015

Dooley and Hirschi crops destroyed by scab

    Thirty years ago, the Dooley pecan cultivar was the nut prized for home consumption by all the workers at the Pecan Experiment Field. Although not a large nut, Dooley shells out in halves producing a beautiful light colored kernel with outstanding flavor. However, over the years this cultivar has become increasingly susceptible to pecan scab. In 2015, our Dooley trees received the same three applications of fungicide that we sprayed on all of our pecan cultivars. Somehow, Dooley nuts still became covered with black scab lesions (photo at right).  This year, the Dooley crop will be 100% stick-tights and we'll suffer a total crop loss on this cultivar.

  Hirschi was another cultivar that suffered from extreme scab infection in 2015.When I inspected the crop on our Hirschi trees, I found that some shucks had split in spite of a 100% scab infection. The photo at right gives you a good idea of how scab effects nut production. The Hirschi nut cluster on the left side of the photo was photographed in Illinois and was largely free of scab infection. The scab covered Hirschi cluster came from our trials in Kansas. Nut size is significantly smaller for the Kansas grown Hirschi pecans where shucks are covered in scab.
    The difficultly we've experienced controlling scab on Dooley and Hirschi in 2015 has also occurred in previous growing seasons. Our inability to control scab on these two cultivars means that I definitely won't be grafting any more Dooley and Hirschi in the future.

Friday, October 9, 2015

Pecan cultivars ripening during first week of October

Caddo, 8 Oct. 2015
  Yesterday, I took a quick tour of our research trials to find pecan cultivars that ripened during the first week of October. I found that Caddo, Chickasaw, Greenriver, Jayhawk, Lakota, Niblack, and Oswego had split shuck since the last time I checked our cultivar trials on September 29th (photos at right and below) . Judging from the crop loads I'm seeing on all trees, both improved and native, 2015 will be an excellent harvest year.

Chickasaw, 8 Oct. 2015

Greenriver, 8 Oct. 2015

Jayhawk, 8 Oct. 2015

Lakota, 8 Oct. 2015

Niblack, 8 Oct. 2015

Oswego, 8 Oct. 2015

Thursday, October 8, 2015

Fall nitrogen fertilization

Since the weather forecast calls for a 60% change of light rain tonight, we decided to apply our fall fertilizer today (photo at right). Hopefully, a light rain will fall over night, melting the fertilizer pellets  and washing the nitrogen into the soil.
    Our fall fertilizer program calls for the application of 100 lbs./acre of urea, which amounts to 46 lbs./acre of actual nitrogen. We broadcast this fertilizer over the entire orchard using a standard buggy we rent from our local fertilizer dealer.
   This fertilizer application is timed to coinside with the fall flush of pecan root growth that occurs as the trees start to prepare for dormancy. Actively growing roots are far more efficient at taking up soil nutrients than roots that are quienscent.

Wednesday, September 30, 2015

Nut shape defines kernel characteristics

   The other day I was cutting pecans in half to check on kernel quality when I made a simple observation. Nut shape has a huge impact of a couple of important pecan kernel characteristics.
    As I walked down one of our tree rows, I came across three early-ripening cultivars; Faith, Gardner, and USDA 75-8-5. In cross-section,  Faith and Gardner have a similar nut shape--nuts are wide and seem flattened on the suture side (photo above). In contrast, nuts of USDA 75-8-5 appear narrow when viewing the nut from the suture side but are wide in the opposite direction.
    When kernels are extracted from these nuts Faith and Gardner kernels will appear much larger than the 75-8-5 kernels simply because they will be much wider. Now, look at the shell packing material that fills the space in the dorsal grooves of each kernel half. Note that the packing material forms a wide "V" shape in the Faith and Gardner nuts. In comparison, the USDA 75-8-5 nut has narrow fingers of packing material inside deep dorsal grooves.  Narrow dorsal groves often trap bits of packing material in kernel halves making the shelling process more difficult. The "V" shape of the dorsal grooves inside Faith and Gardner nuts will mean that all fragments of packing material will fall free from the kernels during nut cracking.