Fruit and Water

As I said when I came back to it, I see a continuity between the water focus of the beginning of this blog, and my current exploration of local food systems. So here, in another nod to the past, is a link to a very interesting article from the Amador County Ledger-Dispatch about how reducing irrigation to orchards is not only possible, in that less water doesn’t kill the trees, but can actually improve both fruit yield and even quality. It focuses on UC researcher David Goldhamer, who has changed grower practices with his findings:

It was common for farmers to neglect irrigating almonds after harvest so, as an aside, the scientists also compared irrigation regimes carried out after harvesting the trees.

“We found that post-harvest irrigation was critical for sustained yields,” he said. “At that time, you would commonly see almond orchards defoliate right after harvest. Not anymore. This research fundamentally changed how we irrigate almonds in the southern San Joaquin Valley. This finding was a big revelation to us as well as the growers.”

The research also produced another surprising result. Beth Teviotdale, a now-retired plant pathologist who was working with Goldhamer’s group, observed changes in the amount of hull rot that occurred under various irrigation regimes.

“We found that if the trees experience water stress during the first two weeks in July, the occurrence of hull rot is significantly reduced with little or no reduction in almond yield,” he said. “Some scientists end their careers having never been involved in a discovery that significantly changes grower practices for the better. During the first 10 years of my tenure, I had the pleasure of being part of two.”

I’ve made reference before to how upset it makes me to read about farmers’ bulldozing their trees, whether from lack of water or lack of market, and Dr. Goldhamer has something to say about that:

Recent news reports of farmers bulldozing or stumping mature trees early in the 2009 drought puzzles Goldhamer. Even a small amount of water, if applied at the right time, he said, permits tree survival in water-lean years.

In fact, pistachios, he has found, are especially drought-resistant. Working on the west side of the San Joaquin Valley near Kettleman City, he deprived mature pistachio trees of all irrigation water during a four-year drought. Even though they received only 3 inches of rainwater per year, they didn’t die.

In another study, almond trees that were fully irrigated with 16 inches of water early in the season and then cut off completely suffered fatal damage. However, Goldhamer believes that 8 to 10 inches of water applied at just the right time during the season would have kept those trees alive. This points to the importance of RDI timing.

The article is from late March, but I just saw the link this morning, in David Zetland’s always-interesting Aguanomics.