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Citrus IPM

Citrus IPM News
  • California red scale season has started in the SJV.

    Mar 13, 2024

    Based on traps placed at LREC citrus blocks, California red scale season began with Biofix on March 10. Pest Control Advisors in Kern, Tulare, and Fresno County reported that they have seen activity, but the numbers have been low. If you haven't caught fliers on the traps yet, you are likely to catch some this week.

    CRS Male

    Figure. CRS male. Note the CRS has feathery antennae and a brown band through the waist.

    What is CRS Biofix?

    CRS Biofix is the start of California red scale activity for this season. As weather warms up and heat units are accumulated above the lower developmental threshold of this insects, overwintering females start producing crawlers which develop. Males' complete development and fly to find third instar females to mate. Mated females then produce crawlers which is the First Generation of Crawlers, observed 550-degree days after the biofix.

     What do males on the trap cards mean for management?

    Pest control advisors have long used pheromone cards to monitor males and degree days to predict successive life event (crawler emergence) for timely management of CRS. Trap numbers may be different depending on the management choice.


    CRS pheromone trap

    Figure. 2. Pheromone card. To estimate number of males/trap, count the insects inside square boxes and multiply by 5. 

     IGRs and mating disruption – few male scales on the card as these options affect males more than it does females. You may have lower males on card but have high CRS populations.

      • Aphytis and Movento – Aphytis targets third instar females, thus affecting females more than it does to males. Also, Movento controls CRS on twigs but not on wood. If Aphytis or Movento or both are used, you may see higher males. If Movento was used, check the inner canopy branches, top of the tree for CRS patches.


    Citrus entomology group will monitor degree days for four counties and update it biweekly on ucanr website  https://lrec.ucanr.edu/Citrus_IPM/Degree_Days/

    Stay tuned for updates.

    By Sandipa Gautam
    Author - Cooperative Extension Area Citrus IPM Advisor
  • Invasive Fruit Fly Quarantine: What to know as a SJV citrus grower?

    Jan 25, 2024

    Invasive Fruit Fly Quarantine

    What to know as a SJV citrus grower?

    Sandipa Gautam

    Area Citrus IPM Advisor

    UC Statewide IPM Program Operations

    Several species of invasive fruit flies that belong to the family Tephritidae are considered serious pests of hundreds of agricultural crops including citrus. These flies lay eggs on or near the fruit surface, and when the maggots hatch, they bore into the fruit, making it unfit for human consumption and causing major losses to fruits and vegetable production. California is experiencing an unusually high number of invasive fruit fly detections in the 2023/24 season and several areas in California are now under a fruit fly quarantine. For many invasive fruit fly species, quarantine is triggered when two or more adult flies are caught in a trap or by a single detection of larvae or pupae indicating a breeding population. Core area is 0.5-mile radius around the detection site and a quarantine area is 4.5-mile radius around each detection.

     Counties Currently Impacted by Invasive Fruit Fly Quarantines: 

    • Oriental fruit fly: Contra Costa, Riverside, Sacramento, San Bernardino, and Santa Clara Counties (Figure 1)
    • Mediterranean fruit fly: Los Angeles County (Figure 2)
    • Tau fruit fly: Los Angeles County (Figure 3)
    • Queensland fruit fly: Los Angeles and Ventura Counties (Figure 4)


    Why is fruit fly quarantine concerning to citrus growers?

    Citrus is a known host to all invasive fruit fly species. Fruit fly life cycle begins as eggs laid by adult female on surface or under the fruit rind maggots hatch and bore into the fruit and develop inside the fruit (Figure 5). They drop to the ground and pupate. Many fruit fly species are known to overwinter as prepupae or pupae, but some species like Medfly can overwinter in all life stages inside fruit or as pupae on the ground. Adults emerge in early spring and the life cycle continues. Because eggs and immatures can be present inside the fruit, movement of infested fruit may accidentally transport them to a new area where fruit fly has not been detected.

    Invasive fruit flies – what to look for?

    Four species of fruit flies are currently regulated in California. The adults may look similar to houseflies but are distinctly different in color and the markings on the body. They are about 5-8 mm in size, much bigger than spotted wing drosophila, another invasive species that has been established in California.

    •  Oriental fruit fly: ~8 mm size, bright yellow colored body with a dark T shaped mark on the abdomen (Figure 1).
    • Mediterranean fruit fly (Medfly): ~5-6 mm in size, yellow-light brown body, clear wings with brown bands (Figure 2)
    • Tau fruit fly: ~7 mm in size, yellow body with black markings (Figure 3)
    • Queensland fruit fly: ~5-8 mm in size, wasp-like body, reddish brown in color with distinct yellow markings, clear wings with band along the top margin.

    Figure 1

    Figure 1. Oriental fruit fly adult with identifying characters (left) and areas in California under quarantine as of January 2024: Contra Costa, Riverside, Sacramento, San Bernardino, and Santa Clara Counties (right).



    Figure 2

    Figure 2. Mediterranean fruit fly adult with identifying characters (left) and areas in California under quarantine as of January 2024 – Los Angeles County (right).



    FIgure 3

    Figure 3. Tau fruit fly adult with identifying characters (left) and areas in California under quarantine as of January 2024: Los Angeles County (right).



    Figure 4

    Figure 4. Queensland fruit fly adult with identifying characters (left) and areas in California under quarantine as of January 2024: Ventura County (right).

    You can find more information about invasive fruit fly species including interactive quarantine maps, regulatory information and pest profile information below: https://www.cdfa.ca.gov/plant/PDEP/treatment/index.html




    Figure 5

    Figure 5. Fruit fly larvae are white, legless maggots. They bore into the fruit and feed on pulp. Infested fruit may drop and decay.

     What is happening to prevent fruit fly spread?

    The California Department of Food and Agriculture (CDFA), in cooperation with the United States Department of Agriculture (USDA) and County Agricultural Commissioners, has initiated local regulatory measures to eradicate and prevent the statewide spread of Queensland fruit fly, Tau fruit fly, Mediterranean fruit fly and Oriental fruit fly. California Citrus Quality Council (CCQC) in coordination with researchers is developing a systems approach that allows for post-harvest treatment of citrus fruit for movement from the core to pack.  

     What can you do?

     If you are a grower inside the quarantine area, follow regulations about harvesting, processing, or storing fruit. Contact your County Ag Commissioner about the latest regulations, or review FAQs here: https://www.cdfa.ca.gov/plant/fruitfly/docs/Invasive_Fruit_Fly_FAQ_Industry_1-18-24.pdf . If your property is under fruit fly quarantine, follow either pre or postharvest treatment protocols from USDA to move fresh fruit

    • Grower outside the quarantine area, stay informed, invest in trapping and pre-quarantine treatments to avoid potential harvest delays should a quarantine be established in the future. For information on prevention and exclusion visit: https://www.cdfa.ca.gov/plant/PE/InteriorExclusion/current_preharvest_treatment.html
    • Quarantines boundaries can change rapidly, so it is critical to stay in communication with your local agricultural commissioner.
    • Report any suspected invasive fruit fly sightings to CDFA, USDA or your local County Agricultural Commissioner.
    • Encourage neighbors, friends, and family to avoid moving any homegrown produce from their properties and to cooperate with agriculture officials working in their area.
    • Help spread the “Don't Pack a Pest” message to travelers or those receiving produce in the mail or through other shipping channels.
    • Share social media posts created or shared by CDFA, USDA or County Agricultural Commissioners.

    By Sandipa Gautam
    Author - Cooperative Extension Area Citrus IPM Advisor
  • Workshop on Ants at LREC: Management of Sap-Sucking Pests and Ants in Citrus Orchards

    Are you interested in learning about the management of sap-sucking pests and ants in citrus orchards? Lindcove is organizing a full-day workshop to bring you recent research advances on sap-sucking insects and ant management. The workshop will focus on ants.


    Ants, especially the invasive Argentine ant and the native grey field ant, are serious pests because they protect sap-sucking pests infesting citrus, grapes, and other perennial tree and vine crops, from their natural enemies. In return for protection, hemipteran pests like Asian citrus psyllid mealybugs, soft scales, aphids, and whiteflies reward ants with honeydew, a sticky sugar-rich waste product that ants imbibe and return to nests to feed nest mates. This is an example of food-for-protection mutualism that is highly disruptive to biological control and IPM programs. This workshop will cover the latest developments in ant monitoring and management and will provide overviews of the benefits of ant control and how reductions in ant densities result in very high levels of biological control of important hemipteran pests.

    When: 19 September 2023

    Where: Conference room, Lindcove Research and Extension Center, 22963 Carson Ave, Exeter, CA 93221

    Meeting Registration Link: https://surveys.ucanr.edu/survey.cfm?surveynumber=41086


    Workshop Agenda:








    Mark Hoddle, UC Riverside

    Overview of the Asian citrus psyllid biological control program and the need to control pest ants


    Mark Hoddle, UC Riverside

    Use of biodegradable hydrogel beads and bait stations for controlling pest ants in citrus


    Mike Lewis, UC Riverside

    Infrared sensors and the Internet of Things to automate ant counts in orchards



    Coffee Break


    David Haviland, UCCE Farm Advisor, Kern County

    Ant management research and applications in the San Joaquin Valley


    Soon Il Kwon, UC Riverside

    Cultural control of ants in orchards


    Nicola Irvin, UC Riverside

    Flowering cover crops to promote natural enemy ecosystem services





    Sandipa Gautam, UCCE Area Citrus IPM Advisor

    Hemipteran pests and their management in SJV citrus


    All presenters

    Table visits and posters to observe technologies that were discussed and to interact with presenters and ask questions


    David Haviland/Hoddle Lab

    Field demonstration of hydrogel applications for ant control



    Workshop Ends


    By Sandipa Gautam
    Author - Cooperative Extension Area Citrus IPM Advisor
  • A pictorial guide to rind scarring damage on mandarins and sweet orange published!

    Apr 14, 2023

    Did you know rind scarring damage caused by the same pest could look different in mandarins and sweet oranges?

    A NEW extension article "UCANR publication 8708", brings you a pictorial guide to help differentiate between the damages caused by the same pest on mandarin species and sweet oranges.

    Early-season insect pests, such as katydids, earwigs, and citrus thrips feeding on newly developing fruit can cause rind scarring damage. Resulting scar damages can lead to the downgrading of fruit in packinghouses causing huge economic losses for growers. Highly valued for the fresh citrus fruit (unblemished), managing these surface-feeding pests and minimizing their damage is vital to California citrus growers. Several resources, such as “Photographic Guide to Citrus Fruit Scarring” UCANR publication 8090, published in 2003 exist to help identify various types of damages. But previous work was mainly based on work with sweet oranges.

    With the increasing acreage of mandarins in California, the need for identifying early season rind scarring damage caused by several pests was recognized. Dr. Bodil Cass led a group of researchers from UC Davis in evaluating grower data and conducting experiments at the Lindcove Research and Extension Center. The results of this research are now published as a photographic guide that provides information on how three early-season pests cause damage to mandarin species compared to sweet orange.

    What are the main findings?

    • Damages caused by early-season pests are different in tango mandarin and clementine mandarin.
    • Katydids do not cause feeding damage on tango or Afourer mandarins.
    • Katydid damage on clementine looks like worm damage on sweet orange. It can cause maturing fruit to split and then drop.
      Pictorial summary of katydid damage
      Figure. 1. Pictorial summary showing the different types of damages caused by katydid feeding on young and mature fruit. 

    By Sandipa Gautam
    Author - Cooperative Extension Area Citrus IPM Advisor
  • Low average daily temperatures in 2023 is delaying California red scale season.

    Mar 29, 2023

    Low average daily temperatures in 2023 is delaying California red scale season.

    Sandipa Gautam

    UCCE IPM Advisor

    California red scale is a common pest of California citrus attacking leaves, twigs, fruit by sucking plant sap. If the scale numbers are high serious damage can occur to the trees and highly infested fruit may be downgraded in the packinghouse.

    Biology and seasonal phenology of California red scale

    California red scale has an interesting life cycle. CRS start out as mobile crawlers from overwintering females from a previous season (Figure 1), which only remain mobile until they find a suitable location to begin feeding. Once they start feeding, they do not move and go through development being attached to the feeding spot. Males are the only other moving stage (Figure 2). They go through active feeding stage (instars) and a dormant period (molting). Females molt twice and males molt four times and emerge as fliers. Males then find and mate with third instar female. Afterwards, gravid female starts producing crawlers, hence completing the life cycle. In the San Joaquin Valley, there are four complete generations of CRS. In years with warm winters/hot summers, fifth generation crawlers/immatures have been found.



    Figure 1. CRS female (overturned) showing crawlers. Crawlers move around looking for feeding spot, settle and spend life on the same spot.

    Figure 2. CRS male adult (top) and CRS males on trap card (bottom)

    Monitoring male flights using Pheromone trap cards (Figure 2) and using degree days to predict the next life event - crawlers, male flight is a most used method for monitoring CRS seasonal activity in the San Joaquin valley. After every 550-degree day unit accumulation above the lower developmental threshold of CRS, 53°F, something important happens. My team at Lindcove Research and Extension Center has been monitoring degree days in Kern, Tulare, Fresno, and Madera counties. However, we have not had a biofix (first male flight) this year. Please visit https://lrec.ucanr.edu/Citrus_IPM/Degree_Days/ for degree day updates.

    The average mean temperature in 2023 has been lower, what does this mean for CRS season?

    Temperature data from CIMIS Station, Kern Co., shows that the cumulative heat units above the CRS lower developmental threshold trails lower than earlier years in 2023. To date, no male fliers have been caught in Kern Co. which is usually a week or more ahead of Fresno, Tulare, or Madera Counties. This indicates that CRS is developing, but at a slower rate than it had been in earlier years (Figure 3). Expect CRS male flights, crawler emergence to be 2-3 weeks late than normal years, at least for the first generation. If the summer temperature pattern stays similar to earlier years, we will have a delay in second and third generation too!

    The effect of low temperature delaying the development, thereby affecting emergence and flights, will likely affect spray timing for CRS control in 2023 season.


    Figure 3

    Figure. 3. Cumulative degree days above the lower developmental threshold, 53°F, for CRS. Note, 2023 (green line) trails below other years.

    California red scale trial- 2022

    During 2022, our group studied the impact of multiple insecticide treatments on California red scale. The trials took place at the Lindcove Research and Extension Center. The trials were conducted as single tree applications and replicated 10 times. One application was made on July 28, following the crawler emergence. We rated the twigs on 23 September and twigs and fruit on 12 October for the presence of live California red scale. We also rated fruit for infestation by CRS, 0=no red scale, 1=1-10 scale, 2= >10 scales/fruit. The insecticides applied were Movento 10 fl. oz, Sivanto 14 oz, Centaur 46 oz, Senstar  20 oz, and Esteem 16 oz. All insecticides were applied with 1% Omni 6E 415 oil. Foliar applications of insecticides were made using a 100-gal high-pressure D30 diaphragm pump sprayer with mechanical agitation with a hand wand sprayer containing D6-nozzle at 250 psi. Treatments were applied in 750 gallons of water, except for Movento which was applied in 250 GPA, and Centaur which was applied at 1,000 GPA.   

    The insecticide that provided the best control in terms of reducing the percentage of fruit infested with >10 scales was Movento (Figure 4). Treatments, namely, Centaur, Senstar, Sivanto, and Movento significantly reduced the total CRS/fruit compared to control. In September, treatments did not significantly reduce CRS/twig compared to the control. In October, Centaur, Sivanto, and Movento, significantly reduced the mean number of mean live CRS on twigs (Figure 5). Treatments should be applied to provide thorough coverage according to the size of the trees, except for Movento which is recommended at 250 GPA at See the UCIPM guidelines for California red scale for more application details.  

    Figure 4. Mean live CRS per fruit on October 12 counts following insecticide treatment. All treatments were applied with 1% oil.


    Figure 4. Mean live CRS per fruit on October 12 counts following insecticide treatment. All treatments were applied with 1% oil.


    Figure 5. Mean live CRS/twig before and after treatments. Treatments were applied on July 28. Pretreatment count was done on July 25, and post-treatments counts were done on September 23, and October 12, respectively.


    Figure 5. Mean live CRS/twig before and after treatments. Treatments were applied on July 28. Pretreatment count was done on July 25, and post-treatments counts were done on September 23, and October 12, respectively.  


    Attached Files:

    By Sandipa Gautam
    Author - Cooperative Extension Area Citrus IPM Advisor
  • Citrus fruit display and tasting weekend at Lindcove REC

    Dec 7, 2022

    This weekend Lindcove hosts the annual citrus fruit display.

    Event: Oranges, mandarins, lemons, limes, grapefruit, pomelos, and citrons and many other citrus varieties – 180 citrus varieties will be on display

    Place: Lindcove REC, 22963 Carson Avenue

    Time: 9:00 AM to 12:00 PM.

    December 9, Friday, LREC fruit display and tasting is open for the citrus industry from 9:00 AM to noon. Taste fruit at your leisure and discuss low seeded varieties and new varieties with Tracy Kahan and Mikel Roose and pest and disease management issues and horticultural issues with various UC researchers. Following the UC safety guidelines, fruit display tables will be setup outdoors in an open space.

    Dr. Gautam is organizing a display of citrus disorders for FFA students from 2:00 PM to 5:00 PM. 

    December 10, Saturday, LREC open from 9 AM to noon for the public to taste 180 varieties of citrus. Master Gardeners will be assisting and providing answers to backyard horticultural questions. Take a bag home for $5! Several varieties, Cara Cara, Navels, Mandarins, lemons will be available.

    Hope to see you!

    No description available.No description available.

    By Sandipa Gautam
    Author - Cooperative Extension Area Citrus IPM Advisor
  • California red scale – it’s that time of the year to make spray applications!

    Jul 8, 2022

    California red scale is a key pest of citrus in California. Its life cycle starts as crawlers produced by overwintering females from the past season. Crawlers move and find a suitable place to start feeding. Once they have settled they do not move. Traditionally growers have managed scale populations using insecticides. Insecticide applications give the best results when the population is at the most susceptible stage and is uniform.


    California red scale: crawlers emerging from female (left), fruit infested with CRS (right)

    Pheromone trap cards (catch males) and degree days accumulation (predict the next life event - crawlers, male flight) is the most used method for monitoring red scale population activity in the San Joaquin valley. For the last several month's Entomology research team at Lindcove Research and Extension Center has been monitoring degree days in Kern, Tulare, Fresno,  and Madera counties. The latest update as of July 07, 2022, shows that degree day accumulation in all these counties has exceeded 1650, degree days, a threshold for the second-generation crawler emergence. Pheromone traps are used to monitor male flight activity. Following the biofix (first male flight), degree days are used to predict when the crawler emergence or next-generation flight takes place.  This helps growers make timely spray applications to target the most susceptible life stage. Please visit Degree Days for county-wise information. Degree days are taken from CIMIS weather stations in different counties.

    When to spray insecticides?

    • First and second generations have a more synchronized population. The current population in the SJV is the second generation.
    • Crawlers and first instars are the most susceptible stage (thin wax layer).


    Degree days as of July 07, 2022: Degree days are heat units accumulated above the developmental threshold, 53°F, for California red scale.

    Kern County: 1939 DD. Second-generation crawlers started emerging at 1650 DD. Make spray application without delay! Crawlers and white caps (first instar) are the most insecticide-susceptible life stage.

    Tulare County: 1695 DD. Second-generation crawlers are out. Plan to make an application in the coming week. Crawlers and white caps are the most insecticide-susceptible life stage.

    Fresno County: 1764 DD. Second-generation crawlers are out. Plan insecticide application without delay. Crawlers and white caps are the most insecticide-susceptible life stage.

    Madera County: 1715 DD. Second-generation crawlers are out this week. Plan insecticide applications. Crawlers and white caps (first instar) are the most insecticide susceptible life stage.

    What to apply?

    UCIPM guidelines have a list of recommended products to use for managing California red scale populations. UCIPM guidelines have been recently updated to include updated information. Please check it out!

    The goal is to maintain CRS at a level that does not result in more than 5% fruit infested at harvest (>10 scales). Pheromone cards may not be a good indicator of field population based on your pest management choices.

    • Aphytis release blocks – pheromone cards overestimate scale numbers, as Aphytis attacks third instar females.
    • Insect growth regulator/mating disruption – pheromone cards underestimate scale numbers as these treatments affect males more than they affect females. For determining if mating disruption is effective – use a threshold of 50 scales per flight.
    • Movento/Admire – not a reliable predictor, especially if you have a history of scale infestation as these products do not kill scale on wood or scale.

    Drop a comment below about your experience with CRS management in 2022!




    Attached Images:

    By Sandipa Gautam
    Author - Cooperative Extension Area Citrus IPM Advisor
  • Monitoring California red scale populations by using pheromone traps and degree days

    May 20, 2022

    Monitoring California red scale populations by using pheromone traps and degree days

    California red scale is an armored scale that attacks all citrus varieties. It attacks all aerial parts of the tree including leaves, fruits, twigs, and branches by sucking on plant tissue with its long filamentous stylet. Heavy infestations cause leaf yellowing and drop, dieback of twigs, and occasional death of the infested tree. Heavily infested fruits with patches of California red scale may be downgraded in the packinghouse. Growers use monitoring methods, i.e., pheromone trapping, examining fruit, and bin counts (at harvest) for making treatment decisions.

    California red scale

    In the San Joaquin Valley, many citrus growers rely on the use of pheromone traps to monitor male-scale flights. Following the biofix (first male flight) degree day units (DD) are used to predict when the next crawler emergence or next-generation flights is occurring. Degree days are heat units accumulated above the lower developmental threshold of an insect and have been long used to monitor the seasonal activity of California red scale populations. Knowing when the most vulnerable life stage of the insect is present helps growers make timed insecticide applications.

    Citrus IPM research group led by Dr. Sandipa Gautam at Lindcove Research and Extension Center updates degree day accumulation in the San Joaquin Valley counties. Information for different counties can be found here

    CRS Degree days LREC Website

    Pheromone traps are used to monitor either weekly changes in male flights or to track densities during flights, especially the fourth flight. 

    The squares represent 20% of the card – you count what is inside the squares on both sides and multiply by 5 to estimate the total number.

    California red scale Pheromone cards

    How to use pheromone traps for weekly monitoring male flights?

    1. Monitor 5 to 6 orchards that have a known population of California red scales every week,so thatyou can determine when flights are occurring and time sprays.
    2. Change the sticky cards weekly and the pheromone lure caps monthly through October.
    3. Use two to four pheromone traps per10-acre block;add two traps for each additional10 acres. 

    How to use trap card information to make management decisions?

    1. Hang pheromone traps with a fresh lure in early March to detect the biofix (first male flight). Historically, biofix for Kern County occurs around the 1st of March, and biofix for Tulare, Fresno, and Madera Counties occurs around March 15.
    2. Use the biofix and degree-days to predict when crawler emergence or next flight is occurring. Degree days are accumulated heat units over the lower developmental threshold of California red scale.
    3. Crawler emergence for first-generation will occur 550 degrees days after biofix.
    4. Subsequent flights will occur at intervals of 1,100-degree days after the biofix of the first male flight (1,100 DD for 2nd flight; 2,200 DD for 3rd flight; 3,300 DD for 4th flight and 4,400 DD for 5th flight). Subsequent crawler emergence for the 1st, 2nd, and 3rd generation occurs at 550 DD, 1650 DD, and 2750 DD after the biofix.
    5. Check the Lindcove Research and Extension Center Website for updated information on accumulated degree day

    How to use pheromone traps to determine areas of heavy infestation?

    1. Use 2 to 4 pheromone traps per10-acre block;add 2 traps for each additional10 acres.
    2. Time placement of traps at the beginning of the biofix for the flight and remove them at the end of each flight and count scales and record the numbers. 

    In the past, when an average of more than 1,000 scales are trapped during the 4th flight and fruit is infested with scale at harvest, a pesticide application is planned for the next season. However, this threshold of 1,000 scales per flight developed in the 1980s is no longer a stand-alone tool for determining when treatments are necessary. It is critical to use other tactics, such as fruit and twig examination.

    Note that pheromone cards are not reliable predictors of scale populations on their own. In all orchards in all growing regions,whether Aphytis wasps are released or not, conduct visual inspections of citrus fruit once a month during August, September, and October to confirm that fruit is free of scale.

    Situation 1: Scale densities on traps may be high, but the fruit is free of scale:

    • When Movento or Admire (and generics) are used because they remove scale from leaves and fruit but not the wood of the tree.
    • Aphytis prefer to attack virgin female scales and the males may escape parasitization, resulting in a high number of male scales on traps.

    Situation 2: Very few male scales on traps, but the scale is found on fruit

    • When insect growth regulators (buprofezin and pyriproxyfen) are used, the frequently molting male scales are more affected than female scales.
    • When mating disruption is used, males cannot find the trap cards so their densities on traps can be very low. A threshold of 50 scales per flight is helpful in determining if mating disruption is effective.

    Consult UCIPM guidelines for management options.


    By Sandipa Gautam
    Author - Cooperative Extension Area Citrus IPM Advisor
  • Citrus thrips field day at LREC

    May 4, 2022

    Citrus thrips field day at LREC

    On April 22, Lindcove Research Center hosted the first field event of year 2022! A field day was dedicated to discussing information on citrus thrips biology, differentiating citrus thrips from flower thrips, citrus thrips damage, and management options available. Rain forecast limited the activity to indoors. The event was kicked by Dr. Sandipa Gautam talking about citrus thrips biology, monitoring, and management options.

    Key discussion questions were on the gallon per acre usage for thrips spray application. Marco Rilandi asked about the precedence of gpa used on research trials and the efficacy of day or night applications. Discussions revealed that most PCAs under optimal conditions would choose to recommend ~200 gpa for thrips spray. Other questions discussed were citrus thrips management in organic orchards. For hands-on activity, participants observed citrus thrips and flower thrips under microscopes and observed scarring damage on fruit.

    For information on monitoring and management, please visit these resources. Citrus thrips talk

    UCIPM guidelines for citrus thrips management.

    Participants II

    Participants of the Citrus thrips Field DayInsert ImageDr. Gautam II

    Dr. Gautam lecturing on citrus thrips


    Can you tell citrus thrips from flower thrips? 


    By Sandipa Gautam
    Author - Cooperative Extension Area Citrus IPM Advisor
  • Citrus mealybug activity is starting the Central Valley!

    Feb 11, 2022

    Citrus mealybug has been increasing issue in the San Joaquin Valley in last 3 years. It has been reported from Kern, Fresno, Tulare, and Madera counties in the past years. It is a hemipteran pest that feeds on plant sap, reducing tree vigor and affects yield. Mealybug excrete honeydew which gets on leaf and fruit surfaces where sooty mold grows.

    Mealybugs are soft, oval flat, distinctly segmented insects covered with white mealy wax, giving it a dusted in flour appearance. Females lay eggs in egg sacs loosely held by white cottony flint. Crawlers when hatched are yellowish in color but soon develop waxy covering once they start feeding. Adult females are 3-5 mm long, wingless, with pinkinsh body covered in white mealy wax. Males are winged and take a longer time to develop then females. 

    Although seasonal phenology of citrus mealybug in the San Joaquin Valley is not well understood, we found actively producing live female populations (with some egg hatch) in first week January. This means that it is just not cold enough for these insects to trigger their overwintering habits. Mealybugs are know to have multiple overlapping generations per year. Females cannot fly and are dispersed either by crawling between trees, assisted transport by ants, birds, wind, machinery or labor.

    With the weather warming up, this is a great time to start checking your orchards, especially if you had mealybug infestation last year. Sampling studies that we initiated this week (February 9, first sampling date) already showed crawler activity.

    Where to look for crawlers and first instars?

    When eggs first hatch, the crawlers are yellowish in color and found around areas where egg sac is. They soon start feeding and develop a dusty white mealy wax covering. Crawlers usually disperse to neighboring leaves and start feeding and are commonly found along the midrib. 

    • If you still have fruit on the tree, check the fruit. Mealybug likes clusters, check for any signs of mealybug infestation. Eggs can be present on navel end or the areas where fruit is touching, or where the fruit is joined to the twig.
    • On leaves with signs of sooty mold - usually found in inside canopy of the tree.
    • Between twigs inside canopy of the tree

    Attached Images:

    By Sandipa Gautam
    Author - Cooperative Extension Area Citrus IPM Advisor