IN YOUR ORCHARD
TIME TO CONSIDER
Did you know that there are over 400 different recognized phobias ? Now, there are the common phobias like arachnophobia (the fear of spiders) and claustrophobia (the fear of tight spaces). There are even odd ball ones like coulrophobia, which is the fear of clowns, and I must admit clowns creep me out! The one that I found humorous was hippopotomonstrosesquippedaliophobia…the fear of long words. No, I am not joking — they used a long word as the designation for the fear of long words. People may have a few phobias, but I believe growers all share one in common: lepidopterophobia! What is that, exactly ? lepidopterophobia is the fear of caterpillars, or in other words, Navel Orangeworm! In a scary movie this would be where the lights flicker, lightning would strike, and you would hear the laugh of an evil genius. Luckily, we’re not in a movie. Today we are here to talk about how we can try to minimize this pest, and how to get rid of this phobia. Now I’m sure you have all heard this before, but I am going to say it again: Navel Orangeworm (NOW) control begins with sanitation . Removing nuts that did not come off during shaking for harvest, also known as mummies , greatly reduces the pest population. It is an accepted industry standard to have no more than two mummies per tree, though some in the southern San Joaquin Valley target one mummy per tree. There are multiple ways you can have these mummy nuts removed, but the most popular by far is by doing a winter shake. Winter shaking can be done throughout the dormant season and is most successful when conditions are right. Foggy conditions are usually considered the best when removing mummy nuts. The moisture from the fog and dew is absorbed by the hull of the nut, making it heavier and softening the connection, so when shaking is done, they easily detach from the tree. Moisture is the key to success but can also be an issue. The lack of it can lead to postponing the shake and too much of it can make it difficult to get back in the field. Growers typically try to have mummies removed from November to early January.
What happens if conditions lead a grower to being a little late to have them removed ? Wes Asai, former University of California farm advisor, wrote an article for West Coast Nut titled “Does Winter Shaking Reduce Yield Potential in Almonds ? ” where he discusses research trials. He tested if there were any effects of a “late” winter shake on almond yields in the subsequent crop year. Asai completed the trials in 2018 and 2019 at two different sites each year. In both trials a control was set up where the control received a normally timed winter shake in December and January. The two “late” shake dates were completed the first and second week of February. Now, we know that in February the buds are starting to push, and bloom could be imminent depending on chill hours, so of course there was some bud loss from the “late” shaking. Asai states, “On the February 6 date, an average of 6,784 buds per tree were removed. On the February 11 shake date an average of 9,626 buds per tree were removed.” This may sound alarming, but keep in mind that usually only 20%–30% of almond blossoms will “set” and ultimately produce an almond. The results of Asai’s trial showed that there was no effect on yield in either of the “late” shake timings . Shaking in February is not preferred, and Asai agrees, but he does state that “…this does demonstrate that if favorable shaking conditions (rain and fog/dew) do not occur until later in dormancy, there is still an opportunity to shake mummy nuts with some bud drop and not negatively affect yields.” Studies like the one Asai completed should give confidence that there is time to get in the field and get the mummies on the ground. Shaking is not the only method of removing mummies. In younger orchards, poling is done to remove the harboring homes of NOW. It is a high labor exercise, but in trees that may be too young to shake it is the most effective. In discussing ways to remove mummies I just mentioned the simplest method — take a stick or pole and knock the mummy out of the tree.
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ALMOND FACTS
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