Pecan trees in New Mexico’s Mesilla Valley began leafing out in earnest at the end of March and the first of April, and while that’s typical timing, the event itself is especially significant for Doña Ana County growers this year.
Up to that point, they had their fingers crossed, hoping their trees survived the rare sub-zero temperatures that plunged this area into a deep freeze in early February.
Adding to concerns, they’ve been told by the Elephant Butte Irrigation District to expect no Rio Grande River water for their orchards until June. Even then, water deliveries are likely to be much less than normal.
This reflects a low snow pack in the mountains of northern New Mexico and southern Colorado, the watershed of Elephant Butte’s water, as a decade-long drought in the region continues. In fact, water deliveries to some of the county’s pecan producers were cut off late last summer as the nuts were filling out, resulting in numerous stick-tights at harvest.
“At this point, I’m cautiously optimistic,” says Jeff Anderson, New Mexico State University Extension agent for Doña Ana County. “Everyone is excited about pecans leafing out, but growers are also facing a critical water situation. We’ve already had a few 90-degree days — if we get a hot spring, with a lack of irrigation water, we’ll have a problem.”
Earlier this month, he viewed one impact of the drought at an orchard south of Las Cruces near the Rio Grande — a tell-tale white crust of salt on the soil surface.
“It’s due to the decline in water quality as the water table drops,” Anderson explains.
Poor bud break and stalled growth could result from water quality problems. As temperatures continue to climb in May, farmers will begin to see leaf edge burn, and by July could be confronted with tree defoliation. That’s why he recommends growers test their soils.
“It’s the only way to determine salt levels in the orchard,” Anderson says. “Also, many growers will be forced to use groundwater this year, if they have wells. It’s a good idea to check the quality of the water to see what’s going on.”
If sodium salts are the problem, soil management practices include providing adequate drainage and plenty of good, pure water, if available, and amending the soil with calcium sulfate (gypsum).
“You can keep pecan trees alive through limited water periods,” Anderson says. “But, it can take them four or five years to outgrow the stress and get back into production.”