As California growers prepare for bloom, timing and crop management decisions are coming into sharp focus. In today’s Growing Edge segment, Poli Francescatto, Valent BioSciences Global Technical Development Manager for Plant Growth Regulators (PGRs), discussed how PGRs can help growers manage bloom conditions and improve nut and fruit set.
Francescatto explained that Valent offers several PGR tools designed to help growers either manage crop load or increase yield potential. In tree nut crops such as almonds and walnuts, PGRs are often used to improve nut set by supporting flower viability during the bloom window.
One of Valent’s key products, ReTain® PGR for California, works by inhibiting ethylene production in plant tissues. Ethylene is responsible for flower senescence and drop, as well as fruit maturation. By reducing ethylene levels, ReTain helps extend flower longevity, giving more time to be pollinated and fertilized. This can be especially valuable during challenging bloom conditions.
Weather plays a major role in determining bloom success. Francescatto noted that hot conditions can increase ethylene production, while cold or rainy periods can limit bee activity. In both scenarios, ReTain can help by extending the effective pollination window. “Give me one or two extra days for pollination,” she said, explaining how extended flower viability can make a difference when conditions are less than ideal.
Timing is critical when using PGRs. Unlike fungicides or insecticides, PGRs must be applied within specific growth stages to be effective. For cherries, applications are typically made from popcorn stage to early bloom, when flowers are most responsive. Francescatto encouraged growers to plan ahead by evaluating bud fertility and monitoring weather forecasts leading up to bloom.
By understanding bloom strength, weather risks, and application timing, growers can use PGRs as a targeted tool to support yield potential during one of the most critical periods of the season.
For more information, visit Valent.com/ReTainCA.