2014 12 09 12.57.032Field fumigation should be considered when replanting almond orchards.

It is the time of the year when many operations begin the process of replanting almond orchards. Orchard removal and eventual replacement is one of the more critical times of farm operations. The decision to remove a block varies by farmer. Some remove blocks based on a cycle of redevelopment, meaning that blocks are removed on a schedule based on age to assist with cash-flow. Some are removed due to expensive or inadequate resources (e.g. water). Many are removed when production drops below a certain profitability level.

Removing a block on profitability can be tricky. Blocks tend to alternate bear. An off year may trigger removal, but it could be coming into an on year. Prices also fluctuate. Therefore, this may not be the best way to decide on removing a block. Another consideration should be determining the the stand of trees remaining in the orchard and the rate of tree loss over the past few years. Commonly, in old orchards, trees are lost to heart rot decay fungi and corresponding wind throw. These losses tend to increase as the orchard ages. If this rate is increasing and the orchard stand is below 75%, removal and replanting should be considered. This is a conservative estimate, and should be evaluated with production records and tree stand for your own operations (This estimate is based on an 80% canopy coverage at maturity with minimal tree losses).

2015 09 14 10.34.28 150x150Trees with kinked or girdled roots do not usually show symptoms until 1-2 years later.

It is the time of the year when many operations plant potted almond trees. Although potted trees are convenient with the year round availability and planting time (almost any month if properly irrigated),  there are a few considerations at planting that must be considered in order to prevent root girdling and future orchard loss.

Root girdling of trees occurs when roots grow in odd directions. These roots wrap over or around other roots or the trunk, eventually preventing the flow of water and nutrients while limiting structural integrity. The problem is usually not noticeable at first, but 6-8 months after planting, the trees begin to show reduced growth. Later, these trees often become victim of wet feet or Phytophthora due to over-irrigation of the tree. Over-irrigation occurs from to the inability to pull water at the same rate due to the constricted xylem and reduced canopy size in comparison to healthy trees. In cases in which the trees survive and are kept through the third leaf, they may snap off at ground level from the shaking process. The issue seems to be more severe with more vigorous rootstocks.

2015 07 30 12.27.471Hull rot can increase the number of stick-tights.

     There have been a lot of reports of poor removal of ‘Nonpareil’ almonds. This issue may be caused by a few different issues, all which require a different management plan. The potential causes as well as some thoughts on management are provided below:

     1. Uneven ripening. Uneven ripening can be caused by several different things. A long, protracted bloom can create a delay in ripening due to the length of time between the first and last fruit that was pollinated and fertilized. Also, vigorous growing conditions can delay the ripening process. These include more than adequate water and nitrogen through the entire growing season. Often, this is observed in younger orchards as they are being “pushed” along with increased water and nutrients. Not much can be done about the long bloom period, but properly timed irrigation and nitrogen applications in the spring (especially early spring) can help reduce excessive vigor.

     2. Hull rot. Once a hull is infected by Rhizopus or Monilinia, a toxin is secreted which leads to the death of fruit wood. As this toxin kills tissues, it can cause them to gum – especially at the peduncle, effectively gluing the nuts to the spur. These nuts are very difficult to remove and hull rot management practices should be utilized to help reduce the occurrence of this disease. In years were humidity is high at the onset of hull split, cultural management practices appear to be less effective.

covercropAlmond grower Gino Favagrossa has been working with cover crops for decades to improve water infiltration in low-permeable soils, but now selects bee-friendly mixes that provide a desirable forage source for bees in his orchard after almond pollination.

     Almond grower Gino Favagrossa plants a cover crop in his orchard not only to improve water infiltration and fix nitrogen, but also to keep bees and his beekeepers happy.

    “Beehive rentals are one of the top three expenses in our budget, and we want to build long-term relationships with our beekeepers that can help guarantee us bees year in and year out,” he said.

    Providing postbloom habitat for bees by planting clover cover crops in his orchard middles gives Favagrossa’s bees a food source between almond pollination and honey production that helps in building those long-term relationships with his beekeepers.

     Given almond industry growth and limited soil moisture due to the ongoing drought, harvest activities are likely to kick up more dust than usual. In an effort to reduce those impacts, Almond Board of California recently hosted a half-day workshop in Modesto to share the latest dustreduction research and techniques, air quality regulations and funding opportunities.

     The event featured experts from UC Davis, San Joaquin Valley Air Pollution Control District, Natural Resources Conservation Service (NRCS) and the Almond Board. In addition, representatives from almond harvest equipment manufacturers Exact Corp. and Flory Industries showcased new technology and innovations related to dust reduction.

2015 harvest time updates 1Dead spurs and branches from Hull Rot in Nonpareil. Applying a fungicide at this point will not reduce damage.

Over the past week, a few interesting observations have been made. These include:
 
     1. Hull rot in Nonpareil appears worse in many ‘Nonpareil’ orchards. This is most likely due to the higher-than-normal humidity levels experienced during the initiation of hull-split. Most of the hull rot appears to be from the black bread mold Rhizopus. The dieback being observed is from the translocation of the toxin back into the limb. This often causes gumming which can reduce the ability to remove nuts during shaking. Applying a fungicide now will not cure the infections or prevent the movement of the toxin.
 
     2. There have been several reports of Fuller Rose Beetles clogging micro-sprinklers. These insects lay a mass of eggs in the opening of the sprinklers, reducing water flow. Surprisingly, reports are even coming from growers who have switched to pop-up micro-sprinklers, which are considered more resistant to clogging. This nocturnal beetle has one generation per year with most of the adult activity occurring in August – October. The beetle needs to feed on leaves for a few weeks prior to laying eggs. Although chemigation of the soil is not effective for controlling the insect or eggs, there is some thought that treating the trunks with a registered broad spectrum insecticide may kill the beetle as it migrates from the soil to the trunk. If attempting this strategy, be wary of the PHI of the product you are planning to use. More information can be found in this presentation and at the UC IPM website (You may need to look under a different crop). Keep in mind that the best long-term management of this pest has been through the use of clog resistant, pop-up type microsprinklers.

 

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