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Navel Orangeworm Sees Almond Hullsplit as Opportunity for Invasion

May 24, 2018
This illustration shows a navel orangeworm.

One of the biggest threats to almond orchards during hullsplit is navel orangeworm (NOW). According to Growing Produce, the 2017 California almond crop was hit especially hard by this pest. Controlling navel orangeworm is essential because not only do infestations bore into the nutmeat and produce webbing, but the damage can also enable fungal infections such as hull rot and aflatoxin. With early-season weather already causing orchard stress, it’s important to reduce the risk of additional damage during hullsplit by managing NOW.


Navel orangeworm moths can be identified by their irregular gray and black forewings and legs. Moths lay their white eggs on mummy nuts that are left over from the previous harvest and on newly-exposed nuts after hullsplit. The larvae can be spotted by their reddish brown heads and crescent-shaped markings behind the head. Pupae can be found inside nuts or hulls.


To help control NOW pressure during hullsplit, here are a couple key reminders:

  • Remember that it’s better to be too early in your spray timing than too late. By the time many almonds begin splitting, there is a small window to protect exposed shells. Follow up with an additional spray about 2-3 weeks after the first application.
  • Harvest almonds as soon as possible to reduce the risk of NOW infection.

Including Besiege® insecticide and Minecto® Pro insecticide at hullsplit in a season-long management program delivers effective control of NOW at a critical timing. Besiege provides broad-spectrum lepidopteran control with excellent knockdown and long-lasting residual. Minecto Pro controls a wide range of lepidopteran pests plus mites with long lasting residual control.

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