Late in 2023, California almond growers started to hear about a potentially devastating new pest, the carpophilus beetle (Carpophilus truncatus).

Jhalendra Rijal, University of California Cooperative Extension integrated pest management advisor, and his colleagues spent 2024 investigating its extent in the almond-growing regions of the state and learning from peers in Australia, where the insect has been a persistent scourge for a decade.

“This year, we at least have the one year of experience with this pest, and we have generated information that is relevant and practical for the growers,” said Rijal.

For example: After an insecticide trial was largely ineffective (likely because the beetle spends most of its life cycle protected within the nut), Rijal has been emphasizing cultural practices like orchard sanitation. Rijal also said growers need to clean up the remnant “mummy” nuts on the ground that serve as overwintering habitat and a food source for the next generation of beetles in the spring.

“Do the sanitation so you can destroy the population from the beginning and you will have less of a problem,” said Rijal.

Another emerging almond disease, red leaf blotch, caused by the fungus Polystigma amygdalinum, has been reported throughout California’s San Joaquin Valley during 2024. Named for the orange-red patches of discoloration on leaves, red leaf blotch in almond has led to significant crop loss across Mediterranean countries. It was unknown in California prior to last year.

“It was pretty surprising, both the quickness and vastness of the spread,” said Alejandro Hernandez-Rosas, a UC Davis Ph.D. candidate in the lab of Florent Trouillas, UC Cooperative Extension specialist in the Department of Plant Pathology at UC Davis.

Hernandez-Rosas said a preventative application of fungicide at petal fall – and then again at two and five weeks after petal fall – appear to work best to manage this disease. He added further research needs to be done to determine the most effective products and optimal timing for growers to make the most of their applications.

And because leaf litter is the “primary source” of the disease inoculum, Hernandez-Rosas added that cultural practices focused on speeding cleanup or decomposition of leaf litter are critical to reduce disease severity. However, it is only effective if done over a wide area in conjunction with neighbors.