What is the science behind the zince fertilizer? I hope the
horticulturist mentioned it.
Tom,
Here's some info on Zn for pecans, from TAMU's webpage on pecan production
in the home landscape:
Zinc
"Frequent zinc sprays are essential for rapid tree growth. Trees deficient
in zinc usually have small, weak leaves, highly branched (rosetted) twigs
at shoot tips and, in severe cases, dieback of twigs and branches. During
the first 7 years, trees grow best if foliar sprays of zinc are applied at
least every 2 weeks throughout the growing season of April through early
August. If the trees are not growing, reduce the spray frequency. Spray
mature trees with zinc at least three times between bud break in late March
or early April and early June. Zinc is needed primarily by young expanding
leaflets. Leaflet expansion on mature trees usually stops by mid-June. Two
of several choices of zinc materials to spray are:
Zinc nitrate is formulated as a liquid. Use 2 to 4 teaspoons per gallon or
1 to 2 quarts per 100 gallons of water.
Zinc sulfate is formulated as a powder. Use 2 teaspoons per gallon or 2
pounds per 100 gallons of water. UAN liquid fertilizer (32-0-0) can be
added at a rate of 1 quart per 100 gallons of the zinc sulfate solution to
improve penetration of zinc into the foliage. Zinc sulfate spray can cause
leaf burn on other trees in the home landscape, especially peaches, plums
and other stone fruits. Zinc sprays are most effective if applied early or
late in the day with little or no wind. The higher humidity under these
conditions allows longer wetting and more zinc absorption. Zinc sprays pose
a minimal hazard to man and animals, yet care should be taken not to
contact the spray directly. Zinc sprays are not likely to stain sidewalks,
houses, cars, etc.
These zinc materials can be mixed and sprayed in combination with most
chemicals labeled for insect and disease control. Consult Texas
Agricultural Extension Service publication L-1140 Homeowner's Fruit and Nut
Spray Schedule for recommended combinations."
My dad is a big proponent of using Red Devil Lye to promote better nut
production on pecans, though he just sprinkles a box on top of the ground,
all around the drip line. I pooh-poohed the idea initially, but maybe I
need to re-think it.