California Ag Network

Tag: Navel Orangeworm

  • What Nut Growers Can Do to Combat the New Carpophilus Pest

    It seems we are always on the verge of some type of apocalypse, and with the new carpophilus beetle invading California tree nut orchards, there is cause for concern.  Watch this brief California Ag Network interview with UC Riverside CE Entomology Specialist Houston Wilson to learn more about this pest and how to stop it from damaging your crops.

  • Efficacy of a Hull Split Spray vs. Sanitation for NOW Control

    Navel orangeworm (NOW) is most effectively controlled with the cultural practice of winter sanitation. Winter shaking almond trees to remove mummy nuts has proven to decrease next year’s NOW damage better than any other approach. The reason for this is clear. NOW overwinters as larvae in mummy nuts left in the tree after harvest and it is in these nuts the population carries over into the next season. Adult moths emerge in spring, mate, and lay eggs on mummies that are still in the trees as the females can’t find the new crop nuts until hull split. The second generation will then put direct pressure on the new crop nuts at hull split and the third generation will chew the nuts up during the harvest period.

    The way almond prices have been going recently, there’s no doubt that everyone is going to have to spend dollars as wisely as possible for the foreseeable future. Although cleaning the trees of mummies during the winter isn’t cheap, it is the method of NOW control where you clearly get the most bang for the buck spent. We’re really playing a numbers game here, and this is one practice that is stacked in our favor by the biology of this pest.

    For example, let’s assume a potential of 50 mummies per tree and 30 of them each have 1 NOW larvae. Half of those are female, and each female lays approximately 85 eggs. At harvest in late July we’re into the third generation, and for arguments sake let’s assume there’s no natural mortality.

    Look at what could theoretically happen to the worm population in one Nonpareil tree with 30 infested over-wintering mummies and no control:

    • 1st generation: 15 females x 85 eggs/female = 1,275 larvae
    • 2nd generation: 1,275/2 (half female) x 85 eggs = 54,188 larvae
    • 3rd generation: 54,188/2 x 85 = 2,302,990 larvae per tree at harvest!!!
                        (Thankfully, there IS natural mortality or else we’d be knee deep in worms!)
    Now, look at the impact of a hull split spray aimed at the second NOW generation. We know that sprays give at best about 60 percent control. This reduces the population but is not nearly as good as sanitation as you will see.
    • 2nd generation: 54,188 larvae x 40% survival after the spray = 21,675 larvae
    • 3rd generation: 21,675/2 x 85 = 921,196 larvae per tree to attack the crop at harvest.
    Now, look at what sanitation does in comparison. Start with the same 30 infested mummies per tree, then winter clean down to 2 mummies per tree. One is female, one is male.
    • 1st generation: 1 female x 85 eggs/female = 85 larvae
    • 2nd generation: 85/2 (half female) x 85 eggs = 3,613 larvae
    • 3rd generation: 3,613 larvae/2 x 85 = 153,531 larvae per tree at harvest.

    (If you can beat the 3rd generation by an early harvest you’re even further ahead.)

    So, a hull split spray reduced the worm population by 60 percent, but sanitation by itself, without spraying, reduced the population by 94 percent! When more NOW larvae make it through the winter, more egg laying will occur next season regardless of what else you do. In relation to the number of mummies left in the tree, expensive chemical treatments next season will only slow the rate of worm damage increase.

    If you have scarce dollars to spend on NOW control, spend them this winter when they will do the most good in a sanitation program. If the entire neighborhood works at this, the positive effect will be multiplied many times over for everyone. If you’ve got neighbors that don’t seem to get it, cleaning your orchard will still be a tremendous help to you. If you have no mummies, the first generation in the spring won’t be able to build up and establish a population in your orchard. You’ll benefit since they’ll have to fly in from the neighbors after hull split before they can begin to hurt your crop.

    Be sure to finish the job by destroying the infested nuts once they’re on the ground. Mow and shred the mummies before March 1st so NOW moths don’t have a chance to emerge. When you’re enjoying mowing during bloom in the spring, take personal satisfaction in seeing the chips and pieces of almond fragments and mangled worm parts fly out from under your mower! — By Joseph Connell, UCCE Farm Advisor Emeritus, Butte County

  • Almond Board Launches New Website to Help Growers Coordinate NOW Mating Disruption Efforts

    In effort to improve area-wide management of navel orangeworm, the number one pest of the California tree nut industry, the Almond Board of California has launched a new website to help growers and PCAs coordinate/collaborate on mating disruption efforts. Funded by a grant from the California DPR, the Almond Board has created this new online tool with support from Land IQ, Blue Diamond Growers, and the UC Cooperative Extension.  Watch this video interview with Jesse Roseman and read more about it in Pacific Nut Producer Magazine.

    Please thank this video’s sponsor Suterra for their industry support.

  • Year-Round Effort Required to Defeat Navel Orangeworm in Tree Nuts

    Although almond trees are at rest and dormant for the winter, growers were reminded at the recent Tree & Vine Expo that their work isn’t finished regarding the fight against Navel Orangeworm.  Watch this brief interview with David Haviland from the UC Cooperative Extension, as he shares year-round tools and practices to stay on top of managing the number one insect pest in the tree nut industry. Read more about it in Pacific Nut Producer Magazine.

    Please thank this video’s sponsor Suterra for their industry support.

  • Navel Orangeworm Sterile Insect Technique Moving Forward

    Many tree nut growers are aware of the pistachio industry’s investment and government support of sterile insect technique as another tool to suppress navel orangeworm populations in the orchard, but recognize that the research takes time and money. So how far have we come and does the technique still have promise for combatting the tree nut industry’s number one insect pest? Watch this brief video to find out, featuring Ted Sheely, a cotton and pistachio grower who has been following this program long before it was used for navel orangeworm. Read more in Pacific Nut Producer Magazine.
    Please thank this video’s sponsor Trece for their industry support.

  • A Word of Caution for Navel Orangeworm Winter Orchard Sanitation

    As almond growers diligently begin their Navel Orangeworm winter sanitation and “Mummy Shakes” as the Almond Board of California puts it, Modesto grower Bill Brush shares concerns about caring for young almond trees amidst these sanitation efforts. Watch this brief interview with Bill and read more about almond orchard practices in Pacific Nut Producer Magazine.
    Please thank this video’s sponsor Suterra for their industry support.

  • Recent Successes & Challenges on the Legislative Front with APG’s Cadee Condit

    Growers finally got to meet American Pistachio Growers’ (APG) new Director of Government Relations, Cadee Condit in-person at the recent APG Summer Luncheon in Visalia, CA. Watch this brief interview with Cadee as she introduces herself and talks about APG’s current priorities on the legislative front. Read more about it in Pacific Nut Producer Magazine.
    Please thank this video’s sponsor Suterra for their industry support.

  • Navel Orangeworm Winter Sanitation Considerations

    Winter sanitation is a critical step in your Navel Orangeworm IPM programs. But when should you start and is it enough just to shake those mummy nuts off of the trees? Watch this interview with Bob Klein from the California Pistachio Research Board as he shares some key insights growers should consider when approaching winter sanitation and read about it in Pacific Nut Producer Magazine.

  • Orchard Sanitation is key to a Quality Almond Crop

    Navel orangeworm (NOW) is the key pest of almonds, causing more income loss due to reject nuts than any other pest. Pesticide sprays, alone, cannot control this pest. A combination of several specific practices has been proven to reduce NOW damage and limit loss of grower income. These practices are winter sanitation, timely harvest and pesticide sprays (where needed). Mating disruption is an additional option that is seeing increasing adoption. The first of these practices on the orchard calendar is sanitation.

    Navel orangeworm find food and shelter in unharvested (“mummy”) nuts through the winter and spring, making those mummies a bridge of trouble from one year to the next in your orchard. Multiple research studies show that NOW damage increases with increasing mummy counts the previous winter. Destroying mummy nuts is the first step towards a cleaner crop and improved grower returns through quality incentives from processors. The goal of orchard sanitation is to turn that “NOW bridge” from a four-lane highway (no sanitation at all) into a narrow footbridge.

    Orchard sanitation is practiced by removing mummy nuts from the trees by February 1 and destroying (flail mow or disc) all nuts on the orchard floor no later than March 1st. In light of the expected reduced nut price for the 2020 crop, some growers may consider eliminating this key step in NOW management to “save money”. This is a risky move. The Sacramento Valley 2021 crop has a good chance to be lighter than the record 2020 crop resulting in 1) fewer nuts/tree and so higher % damage even if NOW populations stay the same and 2) larger nuts, on average, with the potential for poor shell seal and greater risk of NOW damage. Don’t play Navel Orangeworm Russian Roulette with your next crop. Sanitize.

    The following steps are needed for effective orchard sanitation:

      Before January 15, scout an orchard and count mummy nuts in 20 trees per acre. Include all varieties in this count.

      If average number of mummy nuts/tree exceeds 2, sanitation is recommended. The <2 mummies per tree target was developed in the early 1980’s, when industry average NOW damage was around 3.5%, much higher than today’s range of 1.3%. In the high pressure area of the southern San Joaquin Valley, the recommendation is to limit mummies to 1 per 5 trees (0.2 nuts/tree) and 8 or fewer mummies on the ground per Nonpareil tree, based on research from in 2003-2006 in Kern County. However, in 2019, northern California had higher % rejects level than the “high pressure” south San Joaquin Valley. Simply put, the fewer mummy nuts in an orchard, the lower NOW pressure at the start of the season.

      To sanitize, shake trees to remove nuts by January 31. Shaking can remove flower buds as they begin to swell and gain weight in late January/early February. Unless it is an early bloom season and buds begin to swell ahead of normal timing, shaking can be done into early February without reducing yield. Some buds are removed by shaking in early February, but since only 25% flower set = good commercial crop, some bud loss does not mean less crop at harvest. Some growers hand poll after shaking if too many nuts remain.

      Sweep downed nuts into windrows and mow or disc by March 1. Mow slowly (2 MPH) and check for intact nuts after mowing. If some nuts remain intact, mow again. NOW can survive if the nut is intact.

    Final thought. NOW overwinter in almond, walnut and pistachio mummies. NOW are also strong flyers, traveling at least a quarter of a mile to lay eggs. If you sanitize, but your neighbor(s) don’t, your orchard is at risk from NOW damage due to mated female moths, ready to lay eggs, flying over from the neighbors. Talk with your neighbors about sanitizing all orchards in the area and removing seedling “wild” almonds along fence lines as these can harbor NOW, too. — By Franz Niederholzer, UCCE Farm Advisor, Colusa & Sutter/Yuba Counties

  • Progress on Navel Orangeworm Sterile Insect Technique Research

    Most tree nut growers have heard about the sterile insect technique research underway to combat Navel Orangeworm, the number one pest threat to almond and pistachio growers.  But what is the progress on this program and how soon can we expect to see these sterile insects released on a large scale to support California growers?  Watch this brief interview with Houston Wilson from the Kearney Ag Research & Extension Center, UC Cooperative Extension, to learn more.
    Please thank this video’s sponsor Suterra by taking this brief Survey.