Fruit and nut farming isn’t as simple as it seems in a changing environment, new study finds

It’s a simple task to go to the grocery store and buy a bag of grapes or grab a handful of almonds for a snack. However, consumers don't often think of these everyday foods as forms of agriculture vulnerable to weather and climate conditions.

While some crops are planted and harvested annually, fruit and nut trees remain in the ground for many years, known as perennial crops. The difference is important because it determines how producers farm their land.

Because of the longevity of perennial crops, these types of farms are a long-term investment, and once planted, cannot be easily changed, making them susceptible to environmental changes.

A recent study published in the American Journal of Agricultural Economics examined how warming temperatures in one of the leading producers of fruits and nuts in the United States, California, are affecting crops like almonds, walnuts, and grapes.

Virginia Tech researchers Yuanyuan Wen, Ph.D. candidate, and Wei Zhang, assistant professor, in the Department of Agricultural and Applied Economics, along with Julian Alston, professor emeritus at UC Davis, looked at how different stages of a perennial crop’s life: dormancy, bloom, fruit development, and fruit maturity, responded to the changing weather, and how adaptation affected yields.

Seasonal phases for almonds, walnuts, and grapes 

The study finds that the effects of warming on perennial crops are more complex than we thought. It also depends on the growth stage they are in, such as warming during dormancy lowers walnut yields and warming during bloom lowers almond yields. However, in the case of wine grapes, warming during dormancy reduces yields only in the short run.

“Adjusting farming methods can reduce some negative impacts, and in some cases, it can help crops benefit from warming temperatures,” Zhang said. “This emphasizes the need that farmers should not use a ‘one-size-fits-all’ approach, but rather targeted strategies that consider both the type of crop planted and its developmental stage.” 

The study found several limitations. For example, the study did not account for crop quality, which is crucial for grapes. The researchers used simplified assumptions about the timing of growth stages that may not reflect regional variations or future climate conditions. 

Overall, the findings highlight that improving the resilience of perennial agriculture requires an understanding of how climate shifts impact each crop and each stage of its development. 

Original study: https://doi.org/10.1002/ajae.70068