Blue Diamond Almond Facts November-December 2022

ANNUAL GROWERS MEETING

GROWER SEMINARS SUMMARIES

Navel Orangeworm and the Neighborhood Mating Disruption Almond growers recognize that Navel Orangeworm, NOW, is their traditional arch enemy. NOW is the prime cause of quality challenges they face each year, driving significant costs for effective management and control and revenue losses if not controlled. approximately 1,000 degree-days, the second generation feeding on hull split almonds can be completed in 700 degree-days and NOW feeding on pistachios can be completed in 500 degree-days.

According to Dr. Siegel, hull split treatments to control NOW must be timed to the hull split. Larvae emerging from eggs deposited on unsplit almonds do not survive to cause damage to the kernel. Siegel also emphasized several points critical for effective control: 1. Hull split occurs first in the tops of the trees. Thus, growers should monitor the tops of the trees for proper timing. 2. Coverage is critical. Treat every row. Do not make every-other-row applications. 3. Treatments should be made at night. Adult NOW are nocturnal insects. Nighttime treatments can provide the best control. 4. Hull split treatments should be completed with five days. 5. Aerial application of hull split treatments can provide effective control where ground applications are unable to reach high enough into the canopy. Dr. Rijal reinforced critical points of control noted by Dr. Siegel and reviewed the introduction of Mating Disruption, MD, as an effective means of NOW management. Using devices to release pheromones within the orchard during the growing season, growers can effectively disrupt the male NOW moth’s ability to locate and mate with females, reducing the population of larvae and the potential for damage to the crop. Dr. Rijal pointed out that MD is not a replacement of other traditional control measures. However, growers employing MD have been able to reduce losses due to NOW damage by nearly 50% and reduce the amount of insecticides applied by eliminating one hull split treatment. Growers with orchards under higher

While NOW is familiar to all growers having been studied for decades, growers also never miss an opportunity to reacquaint themselves with tried-and-true methods of control and learn about the latest techniques that can provide an edge against NOW losses. Blue Diamond members gathered to hear from Dr. Joel Siegel, Research Entomologist with the USDA Agricultural Research Service in Parlier, California, and Dr. Jhalendra Rijal, Area Integrated Pest Management Advisor with the University of California Cooperative Extension at the 2022 Annual Meeting.

Dr. Siegel noted that given NOW is active within the orchards for nine months of the year, there are several opportunities to effectively impact the NOW population. Orchard sanitation, removal, and destruction of mummy nuts where NOW larvae over-winter remains the foundation of successful NOW management. Siegel also noted that NOW moths emerge from the over-wintering mummies in late April and return to lay eggs on the mummies

Dr. Siegel

again where they are more exposed to control measures. Treatment with an insecticide with adequate residual activity can help to reduce the population of larvae hatching from eggs deposited on the mummies. Research has shown that the NOW generational cycle is influenced by temperature and by the quality of material the larvae feed on. The first generation of the year growing within the mummy almonds is completed in

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ALMOND FACTS

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