Monday, March 10, 2014

Drought Can Cause Headaches, Hangover for Almond Growers

It’s called the hangover effect in the almond industry: Providing less irrigation water will reduce vegetative growth and yield not only this season but the following year.
The drought will impact orchards in 2013 and 2014.

“Even if we go into 2015 irrigating at full water demand for a tree, we still have a hangover effect and the loss of yield,” explains David Doll, a farm advisor and pomologist with the University of California Cooperative Extension in Merced County.

Doll tells growers that severe water stress will result in a reduction in kernel size. If the drought worsens and trees receive even less water, growers can anticipate an even gloomier picture: A textured, smaller and more shriveled kernel as well as a lower yield per acre.

Indeed, it’s going to be a challenging year for the $4 billion a year almond industry and state’s No. 1 export crop. In recent years, almond production has been around 2 billion pounds a year.

Bee pollination still going on.
With a third straight dry year and tight water supplies looming, farm advisors are spreading the word to growers about how they can protect the 800,000 acres of fruit-bearing almond trees. They should brace for a tough year on the production side – something that could translate into higher prices for consumers.
It's best to avoid feast or famine irrigation.
Normally, almond orchards need 42 to 48 inches of water each season. A lot of growers this year expect to receive six to 12 inches of water for their trees. Remember the federal Bureau of Reclamation anticipates no water allocation for some farmers, especially those served by the Westlands Water District.

Doll points out studies which indicate trees can survive with as little as 7.6 inches of water in a season as long as the trees maintain their leaves through the fall. Growers, though, shouldn’t worry about partial pre-harvest defoliation. His advice: Growers should stretch their water supplies as much as they can over the season and in proportion to evapotranspiration (ET).  For example, if growers have 30 percent of their water allocation, then they should 30 percent of the calculated ET. It is best to avoid a feast or famine irrigation practice – over watering and then under watering.  

Using a pressure chamber to measure water stress in trees.
Other almond experts say growers should save enough water for post-harvest during bud differentiation from late August to early September. This preserves next season’s crop production. Also, they should check moisture status, track ET and use a pressure bomb to schedule irrigations according to water potential and stress on the tree.

During the early season, Doll adds: “Make sure you stress your trees a little bit before you apply your first irrigation.”

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