Wood grain pattern at the graft union

    Back in 2007 we had an ice storm that caused a lot of damage to our pecan grove. In one of our cultivar trials, I found a tree that had suffered massive trunk injury caused by an adjacent tree falling completely over during that storm. Six years later that tree is still trying to heal over the wound (photo at right).
   Interestingly, this tree wound has revealed the wood growth patterns of the tree's graft union. In a previous post, I have shown you what a graft union looks like from the inside (a cross section through the wood). With the bark removed from one side of this tree, we can now see the wood of a graft union from the outside. Note the raised ridge of wood that runs horizontally across the trunk. The color of the exposed and weathered wood is lighter above the graft than below.

  The photo at left is a close up of the graft union. The grain of the wood has a distinctive swirl at the point where the scion meets the stock. I've see this swirl pattern in other grafted trees including apple and peach trees.  Why the swirl? I guess I could make up some fancy explanation, but this time I think it best just to sit back and enjoy looking at one the of nature's miracles. 

Mid-season pecan cultivars ripen in late September

   Today's weather was prefect for checking on the development of this year's pecan crop. I found that five more cultivars had split their shucks since last week. Here we are, the last week of September, and I'm seeing cultivars that usually ripen in mid-October fully shuck split today.

Lakota

    Lakota was shuck split today, one week after Pawnee and Kanza. USDA 63-16-182, a sister of Pawnee, was also shuck split today. Greenriver, Chetopa, and Jayhawk had split their shucks over the past week but Giles, which usually ripens at the same time as Chetopa,  was still not mature. Jayhawk, a Giles seedling, also matured before its parent cultivar.

USDA 63-16-182

Chetopa

Greenriver

Jayhawk

   

Snap! A young pecan tree breaks in the wind.

     Last week we had a few summer thunderstorms that packed some pretty good winds. Following the storm, I found a young trees snapped in half (photo above). How frustrating!

     My first thought was to see if I could discover why this tree, out of all the trees on the farm, broke in two.  I took a close look at the fractured stump (photo at right). I noted that much of the break was splintered except for two areas of smooth breaks on the southwest side of the tree (yellow arrows). From the appearance of the wood, these smooth breaks were probably present inside the tree even before the tree broke over in the wind. This observation was cause for further investigation.

     I used a chain saw to cut through the trunk of the tree just below the break (photo at left). I found discolored wood on the south by southwest side of the tree. The tree became prone to wind breakage because nearly 1/3 of the tree's supporting wood was dead and starting to rot. What caused this wood decay? The sun.
     This tree was a victim of  overzealous tree pruning. To get lower limbs out of the way of mowing or other tractor operations, too many low limbs were removed from this tree all at one time. This exposed a previously shaded trunk to intense heating by the midday and afternoon summer sun. This heat build up on the south and southwestern portions of the trunk killed the cambium halting all wood and bark growth. The resulting dead tissues attracted wood rotting fungi and the tree was unable to heal over the sun-scalded trunk.
   Now that we've lost the entire top of this young tree and the remaining stump is severely damaged by wood rot, I've decided to cut this tree off at ground level and allow a stump sprout to form a new trunk. In a couple of years, we'll need to re-graft the tree. With all the root energy this tree will have to push new growth, we should be back to nut production in no time.

New early ripening cultivars to watch

    Tuesday, I looked at a few of the newer pecan selections we are evaluating to see how they were ripening in comparison to many of our standard pecan cultivars. I found four selections with shucks split.

    USDA 61-1-X resulted from a cross between Barton and Starking Hardy Giant (photo at right). Ken Hunt had evaluated this clone in central Missouri for several years and recommended that it may be better suited a little farther south ( ie. in SE Kansas). This clone has a thin husk that pulls away from the nut at shuck split. This characteristic should mean the nuts will dry on the tree long before we get a killing frost.

    The "City Park" clone came about by planting a Giles seedling in the riverside park along the Neosho River in Chetopa (photo at left). Years ago, I donated several Giles pecan seedlings to the city in an effort to beautify the park. Over the years, I've kept my eyes on these seedlings just to see what happens. One tree produced nuts early and often. Based on the large nut size, the tree we have now called "City Park" looks to be a cross of Giles and Mohawk. We now have this clone grafted at the Experiment Field for advanced testing.

   USDA 75-8-5 is a hybrid of Osage and Creek (photo at right). Thus far, the tree has been very precocious. However, it has been difficult to judge the nut size of this clone because our trees are still quite young and nuts produced on young trees tend to be small. However, as our trees get larger, the nuts of 75-8-5 have gotten larger, ever in a drought year.

  USDA 75-8-9 is a sister to 75-8-5 and has the same parentage (photo at left). Today, 75-8-9 had about 10% of its shucks split indicating that it ripens slightly later than it sibling. 75-8-9 has been a little slower to come into production but heavy nut production on a 4 inch diameter tree is not always a good thing.