California Almonds: Heavy Rains Still Driving Decisions – AgFax

    Almond nuts in the orchard. ©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.
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    Owen Taylor, Editor
    Jenny Holtermann, Contributing Editor


    Unseasonably heavy amounts of rain fell over much of the southern end of the Central Valley this week. Totals of up to three inches fell in places – amounts well above the average rainfall to date for those areas.

    Disease and pest monitoring will be essential now. Temperatures will rise in most of the state, forecasts indicate, and that will favor both diseases and pests.

    Pistachios continue to progress into bloom, while the colder weather may play a role in slowing down development.

    Walnuts are slowly starting to advance.

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    Phoebe Gordon, Orchard Farm Advisor Madera and Merced Counties

    “Temperatures have been cooler than average and we’ve been receiving quite a bit of rain. Take this into account when scheduling irrigation for crops that have leafed out. With cooler temperatures, water needs have been lower than average. You don’t want to over-irrigate and deprive the roots of oxygen.

    “You can start measuring water stress in fields that have completed leafout, using a pressure chamber or with your soil moisture sensors. These can be great tools for determining water needs. 

    “I’m seeing a lot of really great nut set in our area. Nitrogen and potassium needs are driven by tree demand, so this is a year when almonds will be hungry for those nutrients. Remember that 25% of the orchard’s nitrogen need to go on in April.

    “We’re entering the time for early leaf sampling to predict July leaf tissue levels. Sample leaves about 43 days – plus or minus 6 days – after full bloom.

    “Keep an eye out for leaffooted bug. Also, scout for alternaria leaf spot and rust. Temperatures have been cool, which doesn’t tend to favor disease development, but pay attention to the weather forecast and remember that fungicides are protectants. Sprays need to go on before infection periods.

    “A few people have asked about leaf spotting in almonds. These seem partly related to foliar zinc sprays followed by rains. 

    “Pistachio bloom and leafout are progressing. The trees appear to have received adequate winter chill in our coverage area. The cool weather and rain can favor botrytis. Growers I have been in contact with have put on a fungicide for protection.

    “While rain can favor botryosphaeria, infections tend to develop between 80 and 86 degrees, and it’s been much cooler. Treatment can effectively occur at a later time, so monitoring is key.”

    Todd Fukuda, Weinberger and Associates, Hanford

    “The Hanford area received a little over an inch of rain during this week’s storm, but close to two inches fell at Delano. Growers had an opportunity to apply fungicides before this storm pattern rolled in. They made solid ground applications over the last few cycles.

    “So far, almond growers in our area don’t see substantial issues with rust or later-season diseases. We will continue to monitor. Growers managed diseases well during bloom time, with little evidence of jacket rot or shot hole.

    “Fertilizer is still going out in almonds. Pistachio growers will begin fertilizing next week as it dries out after this storm. Fertilizer will be critical as leaves push out and buds start breaking out.

    “We will start monitoring traps next week and also check for leaffooted bugs as it warms up. Traces of mite movement are showing, but nothing is at a treatable stage yet. Those populations, though, can increase as temperatures rise.

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    “Pistachio buds were still reasonably closed at the start of the week’s storm. We did apply a fungicide where we had a decent terminal push and could see leaves and female buds opening. That was mostly in the Golden Hills variety. Kerman remains slightly closed and behind in development.

    “We will continue to monitor the weather forecast. However, if it clears up, we will likely not apply another fungicide. But if at least a 40% chance of rain appears in the forecast, we will likely make another fungicide application in pistachios.

    “Growers are starting to apply fertilizer as we approach full pollination in pistachios. The cold temperatures are aiding in the overlap between male and female buds being open.”

    John Moore, PCA, Growers Crop Consulting, Bakersfield

    “With all the rain we’ve been having, the amount of moisture in the ground could be a potential problem. We are above our average annual rainfall to date, and we have a ways to go before the end of the rainy season. Areas across Kern County measured two to three inches, and the ground is saturated and can’t take any more water.

    “Growers in areas with histories of alternaria, rust or scab are on a regular spray program. However, we will see an increase in fungicide spraying this year, beyond those regular programs. With all this rain, growers will have to adjust the amount of acreage they typically spray.

    “As soon as the ground dries out, growers will be back in the field spraying. After the storm we had this week, the forecast shows 70-degree weather into next week — ideal conditions for disease following a wet storm.

    “While the main benefit of fungicides is from applying before a storm, some fungicides do have reach-back for certain diseases – for example, brown rot. From 50% to 60% of my growers applied a fungicide ahead of this storm. The remainder were at the tail end of their coverage from the last application, and they will spray after this storm.

    “Hail developed in places earlier in the week, and we noticed some green nuts on the ground due to a combination of wind and hail. Small shoots also appeared cut off and on the ground. Historically, we have seen hail damage on grapes at this stage, but not as a significant threat to almonds.

    “We occasionally spot leaffooted plant bugs. Mites are present on small leaves near the crotch of the tree, but we are mostly spotting signs of old mite activity. Thrips are common and they seem to be working to control mites.

    “We are monitoring for navel orangeworm moths in pistachios and almonds. We do not see large numbers, just 2 to 4 moths per trap over the past few weeks. We set a biofix of March 18. Counts remain low compared to a few years ago.

    “Pistachios are leafing out. Most pistachio growth is half an inch to one inch, nothing more than a couple of inches in certain areas. Growers sprayed a fungicide ahead of this storm for the threat of botryosphaeria.

    “In walnuts, we are seeing blooms in early varieties such as Ivanhoe. Serrs are barely into the flower stage. Now would be the ideal time for copper coverage. With the walnut market not looking positive, growers may be opting out of critical applications.”

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

    “The almond crop continues to look strong as nuts size up.

    “Rain over last weekend totaled a half-inch to one inch, depending on locations across the Sacramento Valley. This week, temperatures warmed into the 60s, and next week we’re expecting springtime conditions, with highs in the mid-70s to low 80s, although in the 10-day forecast, we might see another cooldown.

    “Most growers applied fungicides on walnuts and almonds ahead of last weekend’s storm, although we didn’t receive as much rain as other parts of the state.

    “We are keeping a close eye on insect pressure as we head into warmer temperatures. The cooler temperatures during the last rain kept a handle on insect populations. Peach twig borer levels remain low.

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    “Mating disruption products went up at Nickels Soil Lab this week, and monitoring egg counts continues since our March 13 biofix.

    “Many growers were applying fertilizer over last week and maintaining their fertilizer program. With the prediction of a large crop size, they are paying added attention to nitrogen programs. In a crop year like this, early-season leaf samples will be helpful.

    “We are seeing nut drop in Montereys. The tree will shed until it gets to a stage where it can support development.

    “Walnut catkins are out, and we are seeing growth in Howard and Chandler varieties. Late last week and into last weekend, blight sprays were common ahead of the rain.”

    Chris Morgner, PCA, Agri-Valley Consulting, Merced

    “The times sure are different right now. I’m hearing talk of acreage reduction for plantings of fresh produce. With less market access, sales could decrease.

    “With all the rain, we are having trouble getting into fields. The end of last week was beautiful, but then it rained every day since Sunday (4/5). Storm totals ranged from 1.25 to 2.5 inches across Merced and Madera counties.

    “Our area is right in the middle of pistachio bloom and walnuts are getting ready to bloom. The rain could impact some pollination. While it has been raining all week, the storms have broken briefly each day. The cooler weather may slow down bloom and stretch out the timing.

    “So far, we’ve found minimal damage in almonds from wind and rain. Some nut drop had already occurred due to natural shed. Small amounts of trees have fallen over and limbs are breaking from the weight of the larger crop size.

    “Rain can trigger rust and scab in some areas. Fruit bodies of lesions is an area of infection to cause concern.

    “Anthracnose is an added concern with this high moisture, especially in varieties Monterey, Butte and Fritz.

    “Growers have mostly applied two fungicides so far and will be coming back with another fungicide after the storm, taking into account the potential for anthracnose, shot hole and scab. If sporulation is occurring, the fungicide can help.

    “Rust is prevalent on the west side of Merced County. Shot hole and scab are more common on the east side, mimicking the rainfall pattern.

    “Localized hail damage occurred in a 100-acre field with fourth-leaf trees, with varied injury across the field. Hail damaged about a third of the orchard, but with little or no damage outside of the hail’s path. Loss of 25% to 35% is apparent where the hail directly hit.

    “Leaffooted plant bug is showing in certain areas where damage occurs every year. As we find problems, we are treating. The cooler temperatures have helped limit insect pressure.

    “We have seen nut drop in almonds that were lagging in sizing. The drop appears dramatic from wind and natural crop adjustment. However, orchards with a higher amount of drop should have better potential for a good crop set. There tends to be three times as much on the tree as what we’re finding on the ground. From pollination, 20% to 40% of bloom will set a nut that makes it to harvest.

    “Fungicides went out on pistachios at the beginning of bloom for botrytis and botryosphaeria.

    “Walnuts are barely starting to bloom. Chandlers haven’t been through a large blight problem in the past in our area. One grower did spray for a possible blight concern.”

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