Thursday, March 29, 2018

Young pecan trees need training

    It seems like we've been waiting for Spring to arrive for a long time now. But lets look on the positive side, a late spring gives more opportunity to get some dormant pruning done.  I've written extensively about pruning and training young pecan trees in this blog and I'll provide links to some of those posts at the end of this article.
   The photo at right shows a young pecan tree with a well structured canopy. But this didn't happen by accident. This tree was summer pruned each year to train the tree into a strong central leader form with well-spaced, wide-angle lateral branches.

    Left to grow un-pruned, a young, open-grown pecan tree will develop a bushy top with no clear central leader (photo at left). If this tree had received a little selective pruning during previous years, the tree would have grown taller and straighter. Fortunately for owner of this seedling pecan tree, removing most of the top of this tree to place a bark graft on top would give him the opportunity to train the scion into a well structured tree.

    Unfortunately, many folks never get around to training their young pecan trees. The seedling tree pictured at right could have been grafted 15 years ago and the tree trained into a central leader. However, the tree remained a seedling and was never pruned. As a result, this tree has developed numerous narrow branch angles and after 20+ years produces only a few small, native nuts.
   Training trees when they are young will ensure a strong trunk and a healthy branch framework (photo at left). I have posted numerous discussions of pruning to this blog. If you need pruning advice just type "pruning" into the search bar on this page to find these posts. However, I'd also like to point out 3 key posts. Since we are currently still in the dormant season you can start with "Pruning dormant trees".  Most of the basic principles and practices of tree training can be found in my 6 part series entitled "Training young trees". And finally, check out my discussion on training a successful graft. Grafted trees tend to grow fast and unruly so proper pruning is a must for developing a strong central leader tree. Click on the titles below to see these pages.

Pruning dormant trees

Training young trees (a six part series) 

Summer pruning a young grafted tree 

Tuesday, March 20, 2018

Spring fertilizer application

    Today, we made our spring fertilizer application. I like to time this application by carefully watching for the first sign of bud swell. With pecan, bud development starts when the outer scale splits open and the upper portion of that scale is shed (photo at right). It is almost like the bud is taking off its winter hat.
    The swelling of pecan buds is a good indication of when pecan roots are starting to grow. Actively growing roots aggressively mine the soil for nutrients so when fertilizers are applied at this time of year you can be certain your trees will get maximum benefit from applied fertilizer.
   As we have in the past, we applied a mix of Urea and Potash to our pecan grove (photo at left). Urea is white in color and we spread 150 lbs. of urea per acre. Potash is pink in color and it was spread at the rate of 100 lbs. per acre. In total, we spread 250 lbs./acre of fertilizer containing 69 units of nitrogen and 60 units of potassium.
    This fertilizer application follows the one we made last October when we applied 100 lbs. per acre of urea (46 lbs. N/acre).
    Folks often ask how we spread our fertilizer. We rent a fertilizer spreader from our local fertilizer dealer and use it to broadcast the fertilizer over the entire surface floor of the orchard (photo at right).  It took me about half a day to fertilize our 80 acre pecan grove.  

Wednesday, March 14, 2018

Big native pecan tree weakened by wood rot

    Last harvest season, I came across a tree (photo at right) that I was scared to shake. From a distance it just looks like is a big old native tree that bears the scars of the 2007 ice storm (numerous sprouts from chopped-off limbs). It was only when I went to clamp onto the tree that I noticed a large crack in the trunk. I carefully shook the tree in December  but made a mental note to remove the tree come late winter.

    The trunk of this native tree had a large crack running over eight feet in length (photo at left). I looked inside the crack and discovered a rotten cavity inside the core of the tree. This tree was a potential disaster waiting to happen so I decided to cut it down.

    Cutting down a hollow tree can be tricky. The structure of the tree is so weak that you can't predict when or how the tree will fall once you start cutting. I had cut only one quarter around the trunk, when I heard the sound of wood splintering and cracking. I pulled out my chainsaw and moved away from the tree to watch it come crashing down. It was not the prettiest way to fell a tree but at least this potentially hazardous tree was on the ground (photo at right).

    The way the tree split apart upon falling allowed me to photograph the internal structure of the wood. I've labeled the key portions of the tree trunk in the photo above. Starting at the far left is a very normal looking layer of bark. Inside the bark are multiple layers of white sapwood. The heartwood of this pecan tree is reddish brown. As I looked to the center of the tree I came across a portion of the heartwood that was riddled with the white hyphae of a wood-rotting fungus. Fungal decay of the heartwood caused it to become soft and lighter in color. The hollow core of the tree represents the portion of the wood that has been completely broken down by fungal activity.    

    Inside the hollow core of the tree, I found the fruiting body of the wood-rotting fungus (photo at right). This fungus is a member of a mushroom family commonly referred to as shelf fungi. The fruiting body of this mushroom is hard and feels woody. Rather than gills, the underside of the shelf fungus has numerous pores that release spores. The appearance of shelf fungi on a tree is sure sign of significant internal wood rot.