Thanks for signing up!

Look for the Digest in your email twice a month.

Follow Us

Sign up for our Digest to receive the latest agronomic insights and crop management advice for your primary growing region delivered twice a month to your inbox.

NOW is the Time to Break the Cycle

December 19, 2023
Almond hulls and mummy nuts swept to the center of rows in an orchard

Almond hulls and mummy nuts swept to the center of rows in an orchard.

Navel orangeworm (NOW) threatens almond, pistachio and walnut operations, and in some parts of CA, 2023 has seen some of the worst NOW-caused nut losses in the last 20 years. Damage caused by these insects results in unmarketable nuts and reduced yield potential. Heavy feeding by NOW also opens the door for fungal disease, including aflatoxin contamination.

The foundation of NOW management is winter sanitation. This involves collecting, removing and destroying mummy nuts throughout the orchard to prevent overwintering NOW. Additionally, winter sanitation prevents you from harvesting 2-year-old mummy nuts and eliminates a source of sustenance for the first adult stage of NOW in spring.

There are several steps you should take to ensure proper and timely winter sanitation:

  • Estimate the number of mummy nuts per acre. The Almond Board of California recommends counting the remaining nuts on 20 trees per block to get an average.
  • If the average number of mummy nuts remaining on trees is greater than 2, remove them before bud swell by hand poling or shaking the trees.
  • Collect the removed mummy nuts in the center of rows and destroy them by flail mowing. According to the University of California Statewide Integrated Pest Management Program, all mummy nuts and residue must be destroyed by March to reduce insect pressure effectively.

Following these steps consistently helps you reduce NOW pressure in spring. You should also check in with neighboring farms and orchards during the dormant season. NOW travels easily, so it is important to communicate to coordinate winter sanitation practices and anticipate external pressure going into the next growing season.

Depending on the proximity of external NOW pressure, you may still experience heavy pressure in spring. Winter sanitation is key to breaking the life cycle of NOW but can be augmented with insecticides, such as Minecto® Pro and Besiege®, during the growing season and other cultural practices such as early harvest.

Proper winter management is increasingly important due to climate change. Warmer temperatures earlier in the season are conducive to insect activity and reproduction. By 2050, you may need to contend with 5 generations of NOW in 1 year. Breaking the life cycle during the dormant season gives you an advantage against insect pressure.

Sign up for the Know More, Grow More Digest to receive twice-monthly agronomic email updates pertinent to your area.

All photos are either the property of Syngenta or are used with permission.

Syngenta hereby disclaims any liability for third party websites referenced herein.