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.
Chuck Dirkse
January 20, 2018Thanks 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!
David Doll
January 20, 2018You are welcome, Chuck. I am glad you found the information interesting.
David
Chris Morgner
January 20, 2018For 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.
David Doll
January 20, 2018Thanks Chris for sharing your thoughts on mummy removal.
David
Paul
June 11, 2018I have a question for anyone who can answer. I am helping a friend who leases out 297 acres of almond trees. There are approximately 44,000 trees with 3 different varieties. Each row has a particular variety. One of the rows particular variety laden with mummies. It seems that one of the rows was either shaken too early or too late, and was left with many mummies. The Lessee, who we will call Mike, did not re-shake the trees as you have pointed out would have been the proper method. What I would like to know is if they do get infested with navel orange worm how do I tell?
David Doll
June 15, 2018Hey Paul,
Often, navel orangeworm (NOW) will continue to lay eggs on the mummies. The hatching larvae will feed and mature using the old kernel as a food source. Cracking the mummies open to see if there are any larvae would be the easiest way to check. My guess is that 1 – 2 out of five mummies will have larvae.
Hope that helps,
David