Thursday, August 22, 2013

Collecting pecan leaf samples for nutrient analysis

   Each summer we collect leaf samples to determine the nutritional status of our pecan trees. Only by analyzing leaves, can we discover how well our trees are mining each of the essential elements needed for plant growth from the soil. We can also determine if additional nutrients in the form of soil applied fertilizers need to be added to correct nutrient shortages.
   Collecting a leaf sample is simply an exercise in choosing leaf parts that can represent the "average" nutritional status of the tree. In sampling pecan, locate the middle leaf along this year's shoot growth (circled in red, at right). Then locate the middle pair of leaflets on that particular leaf (yellow arrow point to leaflet pair) and remove that pair of leaflets from the leaf.

    In the photo at left, the yellow arrow points to the location where I pulled off the leaflet pair. That pair of leaflets is shown within the red circle.
   When sampling a pecan grove a single leaf sample should contain at least 50 pairs of leaflets. Collect leaflets from a couple of locations on a single tree but then move on to other trees in the grove. Remember your goal to to collect an "average" sample for the entire sampling area.
   If a certain portion of your pecan grove seems to be struggling, collect a separate sample from the trees in that particular area.  As soils vary across the field, tree performance can vary. Leaf analysis is the best tool to identify possible nutritional problems at the root of poor tree performance.