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.

     Soil moisture sensors are great tools to aid in irrigation management. They provide feedback on the movement and depth of moisture within the soil, providing the ability to identify the proper duration of irrigation. Proper use relies on a thorough understanding of the soil characteristics of the orchard, which include soil type, water holding capacity, and salinity level.

     Sensors can be used to help schedule irrigation. Timing of irrigation usually occurs when moisture levels drop below certain trigger points at varying depths. These points are different for every soil and sensor type and require in-field calibration to help reduce unwanted plant stress. Calibration can occur by comparing sensors readings to plant stress responses (e.g. Pressure chamber readings) or to a “feel” test to determine how much water is still available to the plant.

Glufosinate drift can cause trunk damage to young almond trees. Photo courtesy of Brad Hanson, UCCE Weed SpecialistGlufosinate drift can cause trunk damage to young almond trees. Photo courtesy of Brad Hanson, UCCE Weed Specialist

     Glufosinate (Rely 280 and other trade names) usage has increased over the past year due to the increase supply and availability of generics. This herbicide has been shown to be very effective in controlling glyphosate resistant weeds, including fleabane, marestail, and goosegrass and has an important role in orchard weed control.

Gumming of the tree trunk caused by experimental glufosinate application. Photo courtesy of Brad Hanson.Gumming of the tree trunk caused by experimental glufosinate application. Photo courtesy of Brad Hanson.

     One concern of glufosinate usage is plant safety. Accidental applications of glufosinate to the trunk of one to three year old almond trees can cause damage. Field observations and studies by Brad Hanson (UC Weed Specialist) have shown that gumming and a sunken canker can occur three to four weeks post herbicide application. This canker is distinctively different from Phytophthora, band canker, and bacterial canker as there is more consistency of symptoms across the field (i.e. a pattern in symptom occurrence). Within affected trees, symptoms include origination of the irregular shaped canker being above the soil line and in a similar location on multiple trees, the lack of a “sweet” smell, and amber gumming.
     Although the damage appears to be a severe issue, most observed damage has resulted in slightly smaller, mis-shaped trunks. Within a few years – and usually by the first harvest -affected areas appear to be compartmentalized by the enlarging trunk and are rarely visible. Tree loss has not been observed in normal drift incidences.

     The 2015 California Almond crop has been projected at 1.85 billion kernel pounds, down 1% from last year. Yield is estimated at 2,080 pounds per acre, which is 3% lower than last year.

     The subjective estimate is prepared by the USDA National Agricultural Statistics Service, Pacific Regional Office, and was presented at noon on May 5 in the offices of the Almond Board of California. The subjective reports provide early estimates about the coming crop. The estimate is made by contacting a random sample of growers by phone to provide an opinion of their estimates. This year, responding growers represent 29% of the total bearing acreage, which is estimated at 890,000 acres.

     An objective forecast, based on actual counts and measurements taken in 940 randomly selected orchards throughout the state’s almond growing region, will be released on July 1.