Horticulture: November 1996

Mercy! It scares me to realize that pokeweed Phytolacca americana berries are considered poisonous. This tall perennial herb flourished on our homestead in the woods of eastern Oklahoma and was usually loaded with red to purplish berries during late summer and fall. As kids, we were unaware of their danger (ignorance is bliss you know). We crushed the colorful berries to make 'war paint'. Though the berries tasted bitter, their juice daubed on you could sure make one look wounded as we rode those runaway stick horses during a game of 'war'.

I'm now aware that all parts of the plant are considered poisonous, especially the roots and berries. Please know that consumption of only a few raw berries are known to be fatal to infants and small children and to make adults mighty sick. Even in light of this sobering information, I'm still looking forward to next spring and a carefully prepared mess of poke greens (sallit).

The USDA October forecast for the 1996 pecan crop shows the national crop to be 245 million pounds, down from last year's crop of 268 million pounds. Several states including Oklahoma and Texas are expected to produce fewer pecans than in 1995. Oklahoma is estimated to produce 10 million pounds in 1996, down from last year's crop of 19 million pounds. Texas is estimated to produce 40 million pounds compared to 75 million pounds last year.

We have advocated for some time that the management practices and climatic conditions that pecan trees are subjected to in one year influences the pecan crop potentials of those same trees for several years. Dr. Darrel Sparks, University of Georgia pecan researcher, recently published some interesting findings that support this philosophy. He analyzed Georgia's pecan production for the years 1945- 92. He also analyzed Georgia's climatic conditions including daily rainfall and temperature for that same time period.

Dr. Sparks concluded that the recent decline in pecan production in the southeastern United States is due to an unfavorable change in climate. He further noted that previous year's climatic conditions had a greater effect on production than current year's. For example, the previous year's rainfall for May-July was the most important climatic factor influencing pecan production and had an effect about 10 times greater than the current year's rainfall during April-August. Perhaps this is because soil moisture in the previous year affects the number of nuts produced whereas current year's soil moisture affects nut size. The pounds of pecans produced are dominated by number of nuts per tree and not by nut size.

Of further interest is his finding that more rainfall during May-July was not necessarily better. Though pecan trees are quiet sensitive to deficit soil moisture, Dr. Sparks was more concerned about the excess rainfall that often occurred during those three months. Excess soil moisture reduces leaf growth and photosynthesis; consequently, flower formation is suppressed which translates into fewer nuts being set the following year.

This is in keeping with our experiences in Oklahoma and Texas where excess soil moisture, especially along some creeks and rivers are observed to be a major hindrance to increased pecan production in many native groves. Years ago, Mr. Herman Hinrichs, then Oklahoma State University horticulture professor, reminded me, as a student, that good pecan crops in Oklahoma often follow summers that most folks consider as dry. Where excess soil moisture is a problem, we recommend that the immediate site be abandoned or effective surface drainage practices be instituted before investment is made in other management practices such as tree thinning, fertilization, mowing, spraying etc.

Successful pecan production is a long-term venture requiring consistent management practices year after year after year.