How late can almonds be shaken for winter sanitation?

Winter sanitation should occur within almond orchards. Hand poling crews are often needed to knock mummy nuts missed by shakers. Image sourced from The Almond Board of California.

Winter sanitation is critical in managing navel orangeworm (as well as some other diseases) within almonds. Removing this past year’s remaining almonds – also known as mummies – is a time intensive process. Sanitation occurs by winter poling crews or by re-shaking the trees. This “winter-shake” is a quick way of removing the majority of the mummy nuts and, in high mummy-count orchards, is often used in combination with poling crews.

With a dry November and December, winter-shaking of almonds have been delayed. This has led to several questions regarding how late almonds trees can be shook. Work done over 35 years ago by Steve Sibbett and colleagues found no impact on nut set, yield or size when winter shaking as late as January 31st. This was approximately 8 days prior to pink bud. The author concluded that shaking should be concluded by January 25th within the southern San Joaquin Valley, while it could be a week later in later blooming areas. Cited article: http://calag.ucanr.edu/archive/?type=pdf&article=ca.v037n07p20

When winter-shaking, it is common to see buds on the ground. Even though there may be several hundred buds, a reduction of yield shouldn’t be expected. This is due to the large number of buds that are present on an individual tree. For example, in a 3000 lb/acre mature orchard with 140 trees/acre, approximately 40,000 buds are on each tree, based on a 25% fruit set. Even if substantially higher buds drop from the tree after shaking, observations from several researchers suggest that the tree would compensate with a higher set percentage.

Being that this research is over 30 years old, there is a need to update the work. Modern shakers are more effective as well as adjustable. It may be possible to shake closer to bloom without effect (although 8 days prior to pink bud is pretty late….). If wanting to observe the effects at a local orchard, make sure to record the shake speed and timing that was used to shake the orchard. Please feel free to share any thoughts below on winter shaking.

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4 thoughts on “How late can almonds be shaken for winter sanitation?

  1. Thanks for the timely and useful information David. I’ve been stressed about getting the mummies off and how close we’re getting to bloom. Seems like I don’t need to worry. Thanks again!



  2. For Merced and Madera county, my recommendation is to complete mummy removal by February 1 or approx 2 weeks before bloom. This seems to be in agreement with the 35 year old research.



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