California Almonds: Rains Prompting More Fungicides But Are Slowing Pests…For Now – AgFax Tree Crops

    Lady bug in the almonds. ©Sara Savary, AgFax Media

    • Here is this week’s issue of AgFax Tree Crops.
    • Our thanks to BASF and its California team for sponsoring this coverage.
    • Got questions or comments? Let us know.
    Owen Taylor, Editor
    Jenny Holtermann, Contributing Editor


    The lull in recent storms led to great weather this past week, with temperatures in the 60s and 70s across the Central Valley and North State.

    Storms, though, will return this weekend and into the beginning of next week, based on forecasts as we closed this issue. Predicted rainfall amounts vary from a quarter-inch to two inches, depending on location.

    No reports of heavy insect pressure, so far.

    Almond trees are growing well. Our contacts are encouraged by how the potential crop looks at this point.

    Pistachios and walnuts continue to progress in bud and pollen development, moved along by the warmer temperatures.

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    Nick Groenenberg, Independent PCA, Hanford

    “We have had a week of great weather in our area. I don’t think the rain this weekend will cause anything more than a delay in fieldwork. In our area, we don’t have a real history of later storms causing post-petal-fall diseases.

    “Before the last rain, most growers applied their third fungicide, and aren’t spraying ahead of this coming storm. The orchards still have protection from the previous applications.

    “We are finding no signs of insect problems right now. Growers are planning for a mummy spray April 15 to April 20 for navel orangeworm as well as their first miticide application.

    “We haven’t seen any mites yet. The first miticide spray is a preventive application. We try to put that in place before May, which is when mite populations generally increase in our area. 

    “A limited number of herbicide applications have been going out to clean up berms and volunteer almonds. All the rain and wet conditions over the last month had delayed those treatments.

    “Fertilizers are being applied as required. Storms are only having a small effect on soil moisture levels, so between storms, growers are irrigating as needed.

    “Fruit set looks on par. Some Nonpareils are a little on the light side. Last year, hail hurt yields in some areas. Where hail wasn’t a factor, yields were great. So far, potential looks equal to last year.

    “Pistachios are pushing buds and male trees are putting pollen out. The timing seems earlier than usual, perhaps due to warmer conditions in February. More frosted scale is apparent in pistachios, and we’ll monitor to see if treatment is necessary.

    “Onion and garlic growers are spraying fungicides as needed. Alfalfa producers are waiting for the weather to dry out so they can prepare for cutting.

    “It’s still too wet to plant cotton. Farmers are working beds and waiting for it to dry out before they start. Less cotton will likely be planted on the west side this year, based on what farmers are saying.

    “Tomato planting also has been on hold where fields haven’t dried up enough.”


    Tony Touma, PCA, Bio Ag Consulting, Bakersfield

    “Our almond crop is starting to look good. It won’t be as heavy as last year, but it’s still a decent crop.

    “Most growers are fertilizing and irrigating right now. We expect a fair amount of rain over the weekend and into next week, and we’ll see how much falls.

    “While the spider mite populations had been down since the last rainstorm, a small amount are starting to build again.

    “In areas with historical alternaria presence, growers are planning for a fungicide application next week. Generally, it will be the first of three alternaria applications for the season. Orchards have been wet, and that has delayed some treatments.

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    “We are monitoring for leaf diseases. Most of our growers only applied one fungicide spray this year, and a handful haven’t sprayed at all. Last year was an extremely wet year but we didn’t have any main disease outbreak. We don’t anticipate rain being a problem unless we see over an inch, which would trigger a fungicide for most growers.

    “This is the time of year when leaffooted plant bug starts showing up. They can do significant damage in a short time, so it’s essential to monitor and treat when found. So far, we’re seeing them in historical areas, and they aren’t widespread.

    “We set out navel orangeworm egg and pheromone traps ten days ago. Counts appear normal, which we’d expect with with the colder weather.

    “Pistachio female and male flowers are both out at the same time right now. Golden Hills buds are one to two inches long. Kerman is 4 to 5 days behind Golden Hills. The timing of varieties appears to be closer this year. We experienced hardly any frost this year, and more foggy days helped with development.

    “Traps were also placed in pistachio orchards for navel orangeworm monitoring. Irrigation and weed spraying are underway across the area.”


    Franz Niederholzer, UC Farm Advisor, Colusa, Sutter and Yuba Counties

    “Very little rain fell during the storm last weekend in the south Sacramento Valley. Since then, temperatures have been in the 60s to low 70s.

    “A wet storm is in the forecast for this weekend, with the possibility of showers into early next week. The National Weather Service predicts anywhere from three-quarters to two inches of rain across the North State.

    “Fungicides have been going out ahead of this storm in almonds and walnuts.

    “Mating disruption puffers and navel orangeworm strips will be going up at Nickels Soil Lab in different blocks next week. 

    “We’ll be taking spring leaf samples next week to determine how overall nutrition looks across the orchards and a prediction of July leaf nitrogen levels using the UC Davis ESP protocol. Our second nitrogen fertilizer application will start in the next couple of weeks. We may adjust the May nitrogen application – up or down — based on the leaf sampling results.”


    Aaron Beene, PCA, Simplot Grower Solutions, Merced

    “Everything is still rolling along. We are preparing for over an inch of rain Sunday to Monday.

    “The last fungicide application went out 2 to 3 weeks ago, and we are still within the 5-week post-petal-fall window. Where we’re finding signs of scab, rust or shot hole, I’m recommending a fungicide for those leaf diseases.

    “Growers who are seeing an increase in leaffooted plant bug should consider mixing a control material with their fungicide. The general lack of cold weather could increase movement, and it’s crucial to monitor for them.

     “Obliquebanded leaf rollers are showing up in hot spots where they’ve built in the past. Growers are adding an insect growth regulator to their fungicide to knock down pests inside the tree canopy.

    “We are optimistic this year. This appears to be a better crop than we’ve had in the past two years. Growers are concentrating on April fertility for nut fill. Next week, they’ll add a round of nitrogen and follow up in the next ten days with potassium.

    “The remaining growers are finishing up with weed sprays. Most have completed strip spraying.

    “We’ve caught low populations of navel orangeworm in traps over the past one to two weeks. Counts continue to be sporadic., but warmer weather will likely cause an increase in numbers.

    From our sponsor…


    “Walnut catkins are pushing out and past the prayer stage. Early varieties are blooming and have 20% to 30% nutlets out so far. Growers applied copper and Manzate last week on early varieties and this week on later varieties for blight management, walnut scale control and minimizing botryosphaeria in the orchard.

    “Pistachios are just starting to push. They aren’t at a susceptible stage for disease issues, with only half an inch showing. More growth will develop towards April 20 to the end of the month. If moisture continues for the next couple of weeks, a fungicide could be needed.

    “In almonds and pistachios, mating disruption products should be in place from the end of March into early April.”


    Jhalendra Rijal, Area IPM Advisor, Northern San Joaquin Valley

    “We have had relatively cool to mild weather from the rain last week and are expecting more rain over this weekend. Because of the cooler weather, we have not seen much insect activity in our traps.

    “Navel orangeworm pheromone trap counts in both almonds and walnuts remain low, only 5 to 10 moths per week. We have not seen any female activity in pistachio bait traps and nothing in egg traps, either.

    “We have yet to find any stink bugs or leaffooted bugs in our area. Also, no peach twig borer activity has been detected in our traps.

    “For peach and almond growers who are dealing with oriental fruit moth, we made a biofix on February 25 and have recorded 380 degree days as of today (4/3).

    “There have been no codling moth activities until yesterday (4/2), which is not surprising with our relatively cold weather. Last year, the codling moth biofix was around mid-April.

    “We recommend that mating disruption products for navel orangeworm be in the orchards by April 1, but growers can push it until the middle of April this year. For best results in disturbing moth mating behavior, disruptors should be out before the beginning of adult flights.

    “Research done in the last couple of years showed a 48% reduction in navel orangeworm damage when mating disruption is used on top of other practices like mummy sanitation and regular hull split insecticide sprays. The benefit tends to be higher as orchard size increases and with continuous use over multiple years.”

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