A Message from the ACP/HLB San Joaquin Valley Task Force: Now is the Time to Act Against Increased ACP

San Joaquin Valley

On behalf of the ACP/HLB San Joaquin Valley Task Force

To all Citrus Growers in the San Joaquin Valley,

The ACP/HLB San Joaquin Valley Task Force called a meeting on Oct. 8 due to the increased number of Asian citrus psyllid (ACP) trap finds in the southern part of Kern County.  In the last month (September and into October), there have been a total of 35 ACP trap finds in the areas of the south part of Bakersfield, Arvin, Lamont, Mettler and Maricopa.  There were 15 residential and 20 commercial citrus sticky trap finds.  While there have been finds in some of these areas in the past, the amount of detections in this last 30-day period is alarming. The Asian citrus psyllid, as a reminder, transmits Huanglongbing (HLB); the best way to prevent HLB is to control ACP, which the valley has been successfully doing. 2020 has been a suspiciously quiet year for ACP finds but now, it is time to act.

We are now in the late part of the season where most spray programs have already been executed.  A coordinated spray is not recommended at this time.  Kern County growers are encouraged to use an ACP effective material if they have not done so in the last six weeks.  It is prudent for all growers to use ACP effective materials when treating other pests.  Regarding the residential finds, CDFA is at various stages of treating them.  Prior to these finds, CDFA had released Tamarixia radiata in certain residential areas of Kern County. Future Tamarixia releases are scheduled.

The task force wants to convey the seriousness of what is being seen and what it means to our industry.  Unfortunately, the suspicion is that these finds in commercial citrus groves are spilling over from residential properties.  It is up to the citrus industry to deal with this threat.  San Joaquin Valley citrus growers have done a good job using ACP effective materials when treating.  The cooperation shown by growers during coordinated treatments reflects their commitment to keeping ACP suppressed.  Nevertheless, task force members wished to highlight what should be done to help control the Asian citrus psyllid here in the valley.

It is even more imperative to control the psyllid due to the find of a CLas-positive ACP in a commercial citrus grove down in the Riverside area.  That was a wake-up call.  We cannot, as an industry and in good conscience, dismiss that find.  Growers and Pest Control Advisors need to be diligent.  The following best practices must be a part of the regime tending to citrus groves.

What do growers and Pest Control Advisors need to do?  It is easy to say, “follow the best practices”, but there are key elements that the task force believes is important.  All the guidelines should be adhered to, but these are the key elements:

  • Know when and where Asian citrus psyllids might be present.
    • Flush is what attracts the psyllid. Nice, tender leaves and stems are like candy to an ACP.
    • Citrus varieties matter. Lemons flush constantly; grapefruit, oranges and mandarins will have fewer flush cycles.
    • Know when flushes occur. For established trees, it is typically spring or late. Younger trees have extensive, prolonged flush. Topping and hedging will produce flush. Spraying with kaolin also stimulates flush.
    • Temperature determines how long a flush will last. Hot temperatures lead to quick hardening of the plant growth. Cooler temperatures prolong flush.
  • Scout for Asian citrus psyllids (Yellow sticky traps are a passive method to determine presence of ACP).
    • Use both visual and tap surveying.
    • Survey along the borders, psyllids tend to not go deeper into groves unless the population is high (they do not like each other very much). If very wide plantings or very wide wind machine rows exist, then check along them too.  Younger trees and shorter trees will allow the psyllids to travel farther into the grove.
    • Do more frequent surveys during flush. Monthly surveys work when the vegetation is hardened off, unless the trees are close to a find, then sampling frequency should increase.
  • Be aware of inadvertently transporting ACP.
    • Clean equipment used before moving to the next property. This applies to anyone working in a grove; especially picking crews, trimming crews, irrigators, Pest Control Advisors, and the growers themselves.
    • Check clothing and vehicles for insect hitchhikers. Shake out hats, bags and clothing. Sweep down vehicles.
    • Do not park vehicles in the rows, park outside of the grove.
  • If possible, use ACP effective materials when treating other pests, following label instructions.
  • Follow the requirements when moving bulk harvested citrus.
  • Be aware of new developments!

These were felt to be the most important points of the voluntary best practices.  The ACP/HLB San Joaquin Valley Task Force felt it was important to write this letter to all the valley citrus growers because as of this moment, the valley has not discovered a CLas-positive psyllid or a CLas-positive tree.  The members of the task force believe that the industry must operate under the assumption that there are positive psyllids and trees in the valley; they just have not been found yet.  If the industry relaxes its vigilance, that is when Huanglongbing will become established and cause havoc.  Thank you for taking the time to read this and may each and all stay safe and well.

The ACP/HLB San Joaquin Valley Task Force

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