UC Drought Resources Available for Orchard Settings

Some form of regulated deficit irrigation is recommended to weather drought in almonds and walnuts among other orchard crops, according to UCCE’s Mallika Nocco (photo by Vicky Boyd.)

Multiple online resources are available for tree nut growers and other orchard commodities to help combat drought scenarios in California.

California is currently seeing yet another drought as the state declared an emergency for 41 counties on May 12. Many growers and water managers, according to UCCE Soil-Plant-Water Relations and Irrigation Management Specialist Mallika Nocco, are already making difficult decisions such as fallowing annual crops to allocate water for perennials, purchasing water transfers or delaying new plantings.

Nocco shared important online resources created and updated to support growers during drought in a Sacramento Valley Orchard Source post. She recommends UC ANR’s Drought Tip Fact Sheets as a starting point for growers. These fact sheets provide specific information for multiple different crops and water situations, but Nocco pointed out that some form of regulated deficit irrigation is recommended to weather drought in almonds and walnuts among other orchard crops.

Regulated deficit irrigation, according to UC, is a strategy that can be used to maximize yields and profits as water becomes scarce and expensive. The strategy is to leverage the portion of the crop water production function where increasing applied water no longer results in commensurate yield or profit gains.

“Regulated deficit irrigation can also improve crop quality, disease management and harvest management in many cases,” Nocco said, recommending that growers ensure their irrigation systems have high distribution uniformity and optimal application efficiency prior to engaging in regulated deficit irrigation. “Low distribution uniformity will result in poorly regulated deficit irrigation across an orchard.”

Nocco recommends UC ANR’s maintenance of microirrigation systems site and UC Crop Irrigation Strategies for learning more about regulated deficit irrigation.

Careful monitoring of both ET and stem water potential are also critical for regulated deficit irrigation and drought management. Growers can subscribe to weekly emails of crop-specific ET totals on the Sac Valley Orchard ET page. Nocco said growers can also contact local farm advisors to sign up for weekly emails.

The UC Davis Fruit and Nut Research and Information site has resources to learn how to measure stem water potential, calculate baseline stem water potential, and interpret stem water potential data by crop and growth stage. Sac Valley Orchards also has a series of how-to guides on measuring and interpreting stem water potential for everyone from beginners to long-time users.

“This can also be an opportune moment to start formally scheduling your irrigation and maintaining records using a tool like CropManage, which is science-based, free, and continually validated by UC scientists,” Nocco said.

For additional information and support on drought and water management issues across the state, visit the Drought and Water Experts list to find a UC expert for consultation.