On April 22 a field event was held at Lindcove with speakers Joseph Morse from UC Riverside and Jim Cranney from the California Citrus Quality Council. The issue discussed was how California citrus growers are going to prevent fruit from arriving in Korea with live Fuller rose beetle eggs, now that Korea is no longer going to fumigate citrus. Korea will reject citrus shipments if live Fuller rose beetle eggs are found. Speakers suggested that a systems approach that combines several strategies (a combination of skirt pruning, trunk treatments, foliar treatments, and/or post-harvest fumigation) may be necessary to accomplish the goal, since no single treatment provides complete control. The problems with pesticide treatments are that Fuller rose beetle adults emerge from the soil year round, they are difficult to kill with pesticides, and the pesticides must be reapplied to maintain their efficacy. The problems with the post harvest fumigants currently under study (phosphine and ethyl formate) are that they require extended periods of treatment and cold temperature to achieve a high level of kill of the eggs. Research is being conducted on all of these strategies and until it is completed, the best management strategy includes skirt pruning, trunk treatment starting in June, and a foliar spray 600 degree days prior to harvest. More information can be found at this web site, http://ucanr.edu/sites/KACCitrusEntomology/Home/Fuller_Rose_Beetle_384/Management_36/ that includes information on how to build a spray wand for trunk treatments.
Pheromone traps put out at the end of February help determine when the male California red scales begin to fly. Each orchard is slightly different, depending on orientation, density of trees and location in the valley (Kern is quite a bit warmer than Madera). We trap for scales in Tulare County, and call around for biofixes in the other counties. Our web page shows county-wide biofixes of March 18 for Kern, March 25 for Tulare, and likely April 1 for Fresno and Madera. http://ucanr.edu/sites/KACCitrusEntomology/Home/California_Red_Scale/Degree_Days_885/
This is a great site to bookmark and follow to see when 1st and 2nd generation crawlers are emerging. The 1st generation crawlers emerge 550 degree days after the biofix of the first male flight. The newly settled crawlers are the easiest group of scales to control with insecticides. For more information on monitoring and management of scales see the UC IPM guidelines http://www.ipm.ucdavis.edu/PMG/r107301111.html and the Citrograph article "The Proper Monitoring and Management of Californai Red Scale" http://www.citrusresearch.org/citromarapr2012.
Its March and it is the time of year when the cottony cushion scales are maturing into large females on the trunks of the tree. They especially like plantings of grapefruit and mandarins with dense canopies. It is also the time of year when the vedalia beetles arrive and begin laying their bright red eggs on the cottony cushion scale females. The eggs will hatch and the vedalia larvae will consume the eggs inside the cottony cushion scale egg sac. The adult beetles are voracious predators and will eat all stages of the scales. If you have a population of vedalia and are willing to share it, please let us know (Beth Grafton-Cardwell, 559-592-2408, Lindcove Research and Extension Center). It only takes a few beetles to get a population started in a new location and they control the cottony cushion scales better than pesticides.
The UC citrus entomology group is sharing booth L36 with the Citrus Research Board at the World Ag Expo. Come visit us there.
I am often asked what cold weather does to insect populations. It depends on the insect, the stage it is in and where it is located on the tree. For moths such as citrus leafminer, the pupae survive, but many of the larvae inside the mines of tender flush leaves are killed as the flush is burned by the cold. For California red scale, the younger instars tend to die off, leaving mostly the adult stages. Citricola scales are in the 2nd instar stage deep inside the tree infesting twigs and experience very little mortality. Earwigs are deep in the ground waiting out the cold. Asian citrus psyllid immatures would be killed by extended cold periods, but the adults would survive the cold and feed when the temperatures warm during the day. I guess the answer is that even in a freeze year, the cold never gets them all!