Tuesday, October 27, 2015

Waiting for harvest

    Over the past week I've noticed a major change in our pecan grove--the trees have taken on their fall colors (photo at right). Pecan trees never develop flashy fall color but, as the trees prepare for winter dormancy, leaves will yellow then turn quickly to brown before falling from the tree.

   The trees pictured above are grafted to the Gardner cultivar. I walked up to the nearest tree to check on the condition of the nut crop. Even though Gardner nuts has been shuck split for about a month now, the shucks were still green, almost completely covering the nut inside. Sure I could shake the tree at this stage, but that would force me into dealing with green shucks on the cleaning table and a bin full of wet nuts.

  With green shucks still covering the shell, pecans don't dry well. I harvested a couple of nuts and pulled back the shuck to reveal free moisture on the outside of the shell (Photo at left). A quick taste of the kernels inside these damp shells revealed that the nut meat was rubbery and "green" tasting (both indications of high moisture content).
   Harvesting pecans with high moisture content runs the same risks a harvesting grain before fully dry. Wet nuts can mold, heat up, and destroy pecan kernel quality.  If pecans are harvested with high moisture content, they must be dried using a forced air system to remove kernel moisture as fast a possible.
   At the Pecan Experiment Field, we don't have the time or resources to dry large quantities of early-harvested pecans. So we wait for nature to dry the crop. What usually happens is that a killing freeze in early November will kill green shucks. This allows the shucks to finally dry, pull back away from the nuts, and the nuts will dry on the tree.  So for now, we'll wait.

Friday, October 23, 2015

Mid and late October ripening pecans

Chetopa, 19 Oct. 2015
     I've been so busy collecting nut samples in our pecan breeding block that I almost forgot to record photos of some mid and late October ripening cultivars. I completely missed the actual date when Giles and Chetopa ripened but from the photos I took on 19 Oct. 2015 it looks like they had split at least 7 days earlier (photos at right and below). In comparison, Maramec, Oconee, and Stuart have split during the third week of October (photos below).
   In looking over these nut photos, note that Giles, Chetopa, and especially Maramec have scab-infected shucks. Fortunately, the level of scab infection on these shucks did not prevent shuck-split. Oconee and Stuart nuts were free of scab.

Giles, 19 Oct. 2015

Maramec, 19 Oct. 2015
Oconee, 19 Oct. 2015
Stuart, 19 Oct. 2015

Tuesday, October 20, 2015

Hand harvesting nut samples

    Over the past week, I've been harvesting nut samples from each of the trees in our pecan breeding block. This is a slow but exciting process. Because the trees in the breeding block are planted fairly close together, I harvest samples before nuts start to drop to make certain I collect the right nuts for each tree. This means getting up in our hydraulic lift and pulling off nuts still inside their green but split-open shucks. By harvesting nuts this way I have the opportunity to take important notes on scab resistance.
    As I harvest each nut sample and remove the nuts from the shucks, I think about the potential for that tree to become a new pecan cultivar. In selecting nuts for future testing, my priority is to find new pecan cultivars that have good resistance to scab and excellent kernel quality. Nut size is important but if we have learned anything from our experience with Kanza, customers can appreciate a good tasting medium-sized pecan over a large nut that tastes like cardboard.
     The photo above shows some of the nuts I collected late last week. In the top row I have two Pawnee nuts followed by two Kanza nuts. Pawnee and Kanza are the standards by which I measure all potential new cultivars. Nuts from ten different trees in the breeding block are shown in the middle and bottom rows. These ten were among the numerous trees that showed good scab resistance in a year with heavy scab pressure. As you can see the nuts come in all sizes and shapes. Still to be determined is how well these nuts shell out and the quality of the kernel inside the shell.

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.