Thursday, October 31, 2019

Cold wave freezes pecan tissues

   The weather this week has been miserable; Rain, drizzle, and cold temperatures. A late night cold front finally pushed through SE Kansas early this morning and cleared the clouds away (at least for a few days) but ushered in sub-freezing temperatures.  The thermometer read 27 degrees F this morning at dawn, so I was curious to see if the leaves and shucks of my pecan trees would display signs of cold injury.
   This afternoon I walked out to some Kanza trees and found that many leaves looked freeze dried but were still hanging onto the tree (photo at right). Frozen pecan shucks typically appear water soaked after a hard freeze but this morning the shucks looked just like they had last week.

   During previous fall seasons, a morning low temperature of 25 degrees F would cause the leaves to drop off the trees by noon and the shucks to become water-soaked and dark immediately. However, it appears that 27F is just not cold enough to cause total vegetative tissue destruction.
    I'll be interested to see how my trees react over the next few days as temperatures climb back up into the 50's. I expect to see partial defoliation but I'm afraid the shucks will continue to hang tight around the nuts preventing them from falling freely.
    With the soil under my trees rain soaked, it looks like it will be some time before I can start shaking trees and harvesting nuts. But, gosh darn,  its hard being patient. 

Wednesday, October 16, 2019

Making a Fall fertilizer application

    The soil on my farm has finally dried out enough to allow me to make a Fall application of fertilizer to my pecan orchard (photo at right). I like to fertilize in October for two reasons. First, pecan tree roots are making their Fall flush of new growth and fertilizer is most rapidly taken up by new roots. Secondly, adding additional soil nutrients at this time of year helps the tree recover from the stress of nut production before the start of winter cold (helping to avoid possible winter die-back).
  Today, I applied 53 lbs/ac nitrogen, 38 lbs/ac phosphorus, and 50 lbs/ac potassium.  Including the cost of spreader rent, I invested about $64 per  acre for this fertilizer application. That sounds like a lot of money but making regular fertilizer applications is the best way to build tree health and ensure regular nut production.
   I plan to spread additional fertilizer in the early spring of 2020. In my experience, twice-a-year fertilizer application has proven to help reduce alternate bearing and increased overall yield.

Monday, October 14, 2019

Fall pecan tree planting

    Last week, during a spell of rainy weather, I drove across the state of Missouri to pick up a load of container-grown trees from my friends at Forrest Keeling Nursery. Once the weather warmed up a bit, I started planting trees.
    The trees I purchased were grown in 3 gallon pots and had tops that were three to four feet tall (photo at right). I prefer planting trees at this time of year to take advantage of the natural flush of root growth that occurs as trees prepare for dormancy.
    When I plant container trees, the first thing I do is remove the container and inspect the root system (photo at left). The fine white roots you see growing in the potting media are the new roots the tree is creating as the top of the tree starts shutting down for winter.
   You should also note the large, circling roots that have developed along the bottom of the pot. Before planting, I like to prune off circling roots to prevent any possible root girdling that may occur as the tree grows larger.

    The photo at right presents a bottom-side view of the root system. Note how the roots circle around the bottom edge of the pot. At this point, I unwind the circling roots and prune them off at the point they begin their circular growth pattern. From past experience with container trees, I know that new roots will be stimulated to grow from the pruned roots creating several new tap roots.
    After root pruning, the tree has plenty of fibrous roots left to absorb water from the soil to help get this tree established in its new site (photo at left). In the past, I've dug up a fall-planted trees the following spring to find that new roots had grown out into the surrounding soil. Emerging from that large root, just behind the pruning cut will be new tap roots. New lateral roots will develop from the current mass of fibrous roots.
    Before planting a container tree, I like to shake off all the loose potting soil from the root ball (photo at right). This helps force the tree to grow into the surrounding soil as soon as possible. Removing the loose potting media will also mean that I can completely cover the root system with soil to help prevent the root ball from drying out too quickly.
     When digging a hole for the tree, I use a shovel to dig a hole just large enough to fit the root ball. The tree should sit deep enough so that when you back fill in with soil you will cover the root ball with about two inches of soil (photo at left). It is important to note that depth of the soil I  use to cover the root ball is basically just replacing the potting soil I shook off.
     I do not recommend using a post hole digger to dig holes for container-grown pecans. Post hole diggers have two major drawbacks. First they tend to dig a hole that is too deep. If a too-deep hole is back filled and a tree is planted on top of the fill, the entire planting hole will settle over the winter and the tree will end up drowning in a puddle of trapped water. The second disadvantage of using a post hole digger is that the spinning action of the auger acts to compact the inside surface of the hole making it difficult for tree roots to grow out into the surrounding soil.

    When back filling soil around the tree, I start by carefully packing soil in around the outer edges of the root ball. Then, I place a layer of soil over the top of the root system. I pack the soil in firmly making sure not to leave any air pockets. Finally, I firm the soil down around the tree with a little foot pressure (photo at right).

   One thing I've learned about planting container-grown pecan trees is that deer will chomp and pull up any newly planted trees. So, before planting another tree, I always protect the tree with a cage made of welded wire (photo at left). These cages are roughly two feet in diameter and four feet tall. I tie the cage to a single steel fence post to hold it in place.

Tuesday, October 8, 2019

Pecan cultivars ripening in early October

Oswego, 7 Oct. 2019
    During early October more pecan cultivars ripened. On my Monday-Wednesday-Friday trips through the orchard, I recorded more shuck split dates for several cultivars and selections in my breeding program. Once again, I present photos of recently ripened cultivars and a few photos of selections from my breeding project. The date of ripening is given in each photo's caption.

Lakota, 7 Oct. 2019

USDA 64-4-2, 4 Oct. 2019
KT334,  4 Oct. 2019
KT158, 7 Oct. 2019

KT201, 7 Oct. 2019

Wednesday, October 2, 2019

Pecan foliage diseases

    While driving into Chetopa, I've noticed a native pecan tree that has already shed most of its leaves (photo at right). I stopped the truck and walked down into the grove to investigate. Turns out, this native tree was especially susceptible to pecan anthracnose and the disease has prematurely defoliated the tree.
    The combination of a wet summer and no fungicide applications has allowed pecan diseases to run wild in many native pecan groves this summer. I spent some time today taking some photos of some common pecan diseases.
   First up is Brown Spot (photo at left) caused by the fungus Sirosporium diffusum. This is a fairly common late season leaf disease during years of high late summer rainfall. I have only seen this disease in orchards that do not receive regular fungicide applications during the growing season.

    The photo at right shows a pecan leaf with several diseases. The dark black lesions along the midrib of the leaflets is cause by Vein Spot (Gnomonia nerviseda). The  brown leaf scorching of the leaflets is caused by Pecan Anthracnose (Glomerella cingulata) and the brown spots on the leaf blade were caused by the brown spot fungus.
     Pecan anthracnose infected nuts are often confused with pecan scab infects nuts. Nuts infected by anthracnose in mid-summer will turn dark brown, stay small in size and often partially split shuck (photo at left). However, the shucks on the small nut pictured at left with never release from the shell. Nuts infected later in the summer will gain full size but the brown shuck will be slow to open in the fall.
     I also found Powdery Mildew on some nuts. The fungus, Microsphaera penicillata, causes a white powdery substance to form on the surface of pecan shucks. The disease seems to have little impact on nut fill or shuck opening.
    I started this discussion on pecan diseases all because I saw a native tree completely defoliated by the middle of September. The photo at left shows a pecan terminal that has already lost a significant number of leaflets due to anthracnose. As leaves loose their ability to photosynthesize due to disease infection, the tree sheds the damaged foliage. If disease induced defoliation is severe enough, the tree will simply shut down for the season and go into early dormancy. Trees suffering from early defoliation produce few or no nuts the following growing season.