The account’s odd detail is that the damage reaches beyond the leaf: affected fruit is described as browning, too. Leaves can brown and drop early, interrupting the season’s quiet work of filling the crop.
The reported pattern begins with the rainy season and is said to affect pistachio fruit development. That is the full extent of the damage description; it does not identify a California orchard, county, or observed local outbreak.
A symptom description, not a treatment plan
Despite a headline promising control techniques, the material provided describes symptoms rather than a control method. It does not name a causal organism, offer a diagnostic test, or specify a treatment window.
That distinction matters in a crop where a spot on a leaf is not, by itself, enough information to choose a response. The source account supplies no California-specific validation, product guidance, or application rate.
So this is not a basis for adding a spray or changing an existing schedule. It is a symptom description to take to the person who knows the block and can assess whether the observed damage fits a confirmed diagnosis.
Keep the decision in the block
For a grower or PCA, the useful next step is to document where symptoms appear and how they progress, then confirm the cause before choosing a control. The published description does not provide enough detail to distinguish among causes or support a treatment recommendation.
No California county or regulatory body is identified, and no date for a management decision is supplied. The practical checkpoint is the next disease-management decision for an affected block: use a locally confirmed diagnosis and current California guidance, rather than treating this brief account as a prescription.