UC CITRUS ENTOMOLOGY P ROGRAM

Transcription

1 UC CITRUS ENTOMOLOGY P ROGRAM. C ITRUS IPM NEWSLETTER April 2010 Issue 1 California Red Scale First Flight of the Season The biofix (first adult males captured) for California red scale at the Lindcove Citrus Research Center was the week of March 22. The biofix for individual orchards in the San Joaquin Valley may vary 7 to 10 days depending on factors such as geography and variety of citrus grown, so it is important to monitor CRS pheromone traps in orchards that represent your growing acreage. The first generation of crawler emergence will occur 550 degree-days after the male, using a lower developmental threshold of 53 F. Typically, Kern and Tulare county orchards experience first generation crawler emergence a week earlier than Fresno and Madera county, but the difference in biofix between regions is negligible. The crawler stage is most susceptible to oils, organophosphates (Lorsban, Supracide) and carbamates (Sevin). The first instar white cap stage is most susceptible to the insect growth regulators Esteem and Applaud since they block molting. Movento takes several weeks for uptake and seems to work better later in the season, so save that treatment for the 2 nd generation crawlers. More detailed explanations of California red scale control can be found on the UC IPM Citrus web site Weekly degree-day accumulations for Kern, Tulare and Fresno counties can be found on our website at CRS Degree-Days as of April 8: Kern 75 Tulare 69 Fresno 14 Madera California Red Scale Degree-Days 1 st male 1 st gen. crawlers (predicted) 2 nd male 2 nd gen crawlers 3 rd male 3 rd gen crawlers 4 th male 4 th gen crawlers Estimated Degree Days biofix 550 DD 1100 DD 1650 DD 2200 DD 2750 DD 3300 DD 3850 DD Kern March 22 May 17 Tulare March 22 May 17 Fresno March 29 May 24

2 Page 2 Citrus IPM Newsletter Citrus Peelminer Citrus peelminer synthetic pheromone is, well, let s say wimpy at best. Pheromone lures attract less than 10 moths per week, so pheromone traps can only be used to find the initial biofix. We place traps in non-citrus sites such as oleander and walnuts early in the season to establish that biofix. Then, using a lower developmental threshold of 55 F, we know that every 580 degree-days another generation of peelminer moths fly. The 3 rd peelminer attacks pummelos and grapefruit. So treatments for peelminer in those varieties should wait until 1260 degree-days after the biofix. Later in the season (4 th or 5 th ) the peelminer attacks the susceptible varieties of oranges (Atwood, Fukumoto, TI, and Barnfield) and treatments should wait until the 4 th generation. In orchards with a history of heavy peelminer damage, about 50% control can be achieved by using diflubenzuron (Micromite ) to control eggs with the addition of Success, a pyrethroid or an OP for enhanced activity on hatched larvae and adults. Insecticides don t work very well because the peelminer is protected in the mines and attacks low inside fruit that is hard to treat. Because insecticides are only moderately effective, we do not recommend you treat for this pest unless it has been a chronic problem on a susceptible variety of citrus. More detailed explanations of citrus peelminer control can be found on UC IPM Citrus web site ANR color brochure Citrus peelminer and citrus leafminer Weekly degree-day accumulations for Tulare County can be found on our website: Citrus Peelminer Flights 1 st male 2nd male 3 rd male 4 th male 5 th male 6 th male 7 th male 8 th male Estimated Degree Days Biofix 580 DD 1160 DD 1740 DD 2420 DD 3000 DD 3580 DD 4160 DD Host Plant Willow/ oleander stems Willow, walnut, oleander Pummelo grapefruit Pummelo grapefruit susceptible oranges Pummelo grapefruit susceptible oranges Oranges Oranges Oranges Tulare Not observed yet

3 Citrus IPM Newsletter Page 3 Citricola Scale Update Citricola scale can be found on twigs and are in their 2 nd instar brownish form at this moment. During April, they will migrate from inside the tree to the ends of twigs and molt into large, gray, adult female scales. Monitoring for the adult females is important to get an early season warning of where citricola scale will be a problem. Treatments are most effective later in the season when they are in the 1 st instar stage infesting leaves on the outside of the tree. See IPM guidelines for more information. March citricola scale: May be found on leaves or twigs. Small (<¼ inch), flattened and brown speckled. Year Round IPM Program for Citrus If you are new to citrus sampling in the San Joaquin Valley and need pest monitoring forms or an idea of what pests and diseases to sample for during the year as citrus develops, please check out the UC IPM web page within the Citrus IPM guidelines called the Year Round IPM Program For old-timers, this is a great way to demonstrate to your growers or regulatory agencies that you are using IPM tactics.

4 Page 4 Citrus IPM Newsletter Citrus Black Spot found in Florida Florida has been suffering the loss of thousands of acres of citrus due to the bacterial diseases huanglongbing and citrus canker. Now, to add to their woes, citrus black spot, a fungal disease caused by Guignarida citricarpa has appeared in a Valencia orchard in Immokalee, Florida. The symptoms are necrotic lesions on the fruit that makes the fruit unmarketable and in severe cases the disease can reduce the yield of the trees. The disease spreads through dead leaves that fall to the ground and when those leaves become wet they eject thousands of spores that are blown onto fruit in the tree. The main defense for this disease will be copper sprays to protect the fruit from the spores. It is not likely to survive well in California, but it is one more disease that we need to protect ourselves from.

5 Citrus IPM Newsletter Page 5 Asian Citrus Psyllid Update Residential Infestations: Asian citrus psyllid was detected by the California Department of Food and Agriculture (CDFA) in backyard citrus in southern San Diego and Imperial Counties following its discovery in Tijuana, Mexico during the summer of During 2009 that infestation expanded to include a a small area of Orange County and a very large area of Los Angeles County. Quarantine zones were created around those find sites that prohibit movement of citrus and closely related plants that are hosts of ACP outside of the quarantine zone. See this web link for a map of the trap card finds of ACP in California and Mexico and the quarantine zone created around those finds: iles/ca-az-map.pdf. The host plants at the find sites and immediately adjacent properties were treated with insecticides by CDFA. Tempo (cyfluthrin) is applied to the foliage and Merit (imidacloprid) to the soil and this combination has been very effective in suppressing the pest below detectable levels in most situations for many months. CDFA has conducted numerous outreach meetings for the public and residents have generally supported the treatment program. To see a CDFA list of ACP host plants, distribution of the current infestations and quarantine zones: Nurseries that ship into the quarantine zone are required to treat with both a systemic and foliar insecticide prior to shipment to retail stores. See for more details on the citrus nursery approved treatments. The purpose of treating citrus with insecticides at the wholesale nursery level is to prevent psyllid populations from becoming established after the plants arrive at the retail stores. Lack of treatment and heavy infestation of retail plants were major avenues for ACP and HLB to rapidly spread throughout Florida. Psyllids have been detected by CDFA using yellow sticky cards, visually examining new citrus flush, and by using D-VAC (vacuum) machines.

6 Page 6 Citrus IPM Newsletter Citrus Fruit shipping: It is critical that growers do not ship citrus fruit from the quarantine zone into uninfested areas of the state without carefully cleaning the fruit. Psyllids can be transported on leaves and twigs and in bins of fruit. Mexico ACP update Applications of insecticides to control psyllid infestations in the border regions in Mexico, especially in Tijuana, continue. These treatments are critical for the success of the eradication/suppression effort in Imperial and San Diego counties. Commercial Citrus: ACP has been found in three commercial orchards during the past 18 months. In each case, the grower treated the orchard with the psyllid detection and the neighboring orchards with a foliar and a systemic insecticide and ACP has not bee seen since. There are a number of insecticides that are registered for citrus psyllid control including: Danitol, Baythroid, Lorsban, dimethoate, Sevin, Admire, Delegate, Micromite and Movento. The University of California and the Citrus Research Board have been conducting grower/pca sessions throughout the state to develop treatment strategies for ACP. At the moment, the detections have been 1-2 psyllids found per trap or on foliage (very low densities) in a single orchard within a region. Immediate treatment with a pyrethroid is the best control tactic followed by imidacloprid during the time of year when it can be rapidly taken up into the tree (May-Sep). There are situations where this regimen cannot be used (for example, during bloom) and growers will need to use alternative insecticides. Once ACP increases to multiple finds in multiple orchards in a region, then areawide treatment programs will be conducted with an emphasis on early season pyrethroid treatments (Jan- Mar) to kill adults as they attempt to deposit eggs, mid season imidacloprid to prevent nymphs from developing on fall flush, and a late season (October) treatment with a pyrethroid or OP to kill adults as they go into overwintering. For a list of insecticide treatments for commercial citrus: Resources (posters, cards, brochures) in English, Spanish and many other languages can be found at our web site or

7 Citrus IPM Newsletter Page 7 Huanglongbing Disease Update Huanglongbing is a bacterial disease of citrus, transmitted by the Asian citrus psyllid, that causes the leaves to turn mottled yellow, fruit to become small and asymmetrical, juice to become bitter, and eventually the tree dies. There is no cure for the disease and the tree may die in as few as 3 years. It is very important to protect California citrus (both backyard and commercial) from this disease. The disease is found throughout Florida and Cuba and in a few locations in other southern states such as S. Carolina, Georgia and Louisiana. It has recently been found in Belize and Mexico. The disease will most likely arrive in California in the body of an infected psyllid that flies or is carried in on plant material, or it will arrive in an infected tree that is planted here. Treatments of homeowner backyards and commercial citrus are critical for slowing the spread of the ACP, which in turn reduces the risk of HLB establishing and buys time for the scientists to develop a prevention or cure for the disease. HLB infections in residential citrus in Mexico increase the risk of HLB arriving in California in the near future.

8 Page 8 Citrus IPM Newsletter Upcoming Citrus Meetings Bakersfield Tuesday April 20, 2010, 1:00-4:30 pm Kern Spring Meeting Craig Kallsen: Citrus yield, fruit size and pruning Beth Grafton-Cardwell: Update on citrus pests Mikeal Roose: New rootstocks and varieties for the citrus industry Akif Eskalen: Major fungal root rots in citrus and their control Craig Kallsen: Factors associated with early fruit maturity in citrus Location: U.C. Cooperative Extension Office, large conference room 1031 S. Mt. Vernon Ave, Bakersfield Call (661) for directions Bakersfield Thursday, April 22, 2010, 9:00 am 11:30 am Asian Citrus Psyllid Training: Focusing on how you can help with the effort to detect the psyllid in your citrus orchards Beth Grafton-Cardwell, Brian Taylor, Dennis Haines, Michelle Redstone Location: U.C. Cooperative Extension Office, large conference room 1031 S. Mt. Vernon Ave, Bakersfield Call (661) for directions Tulare Friday, April 30, 2010, 8:30-12 noon Spring Citrus Meeting John Karlik: Progress report on air quality research in citrus Ray Yokomi: Screening for virulent strains of tristeza Marylou Polek: Laboratory screening for huanglongbing disease Beth Grafton-Cardwell: Management of leafminer, citricola scale, and Asian citrus psyllid Larry Schwankl: Clogging in micro-irrigation systems Location: Tulare County Agriculture Building 4437 Laspina St, Tulare Call (559) for directions The Citrus IPM Newsletter is published by the University of California Citrus Entomology Laboratory at the Kearney Agricultural Research Center. For information or to subscribe or unsubscribe please send an to gregm@uckac.edu or call Greg Montez at (559) Dr. Beth Grafton-Cardwell, IPM Specialist and Research Entomologist bethgc@uckac.edu University of California Kearney Agricultural Research Center