California red scale crawlers emerge about 550 degree days (biofix in March, lower developmental threshold of 53oF) after the first flight of males. As you can see on the CRS degree day web page, Kern county passed that point last week, Tulare County crawlers are emerging this week and Fresno scale crawlers are soon to emerge. The first or second crawler generations are the best times to treat with most insecticides, because crawlers are most sensitive at this stage.
See the UC IPM Guidelines for Citrus for more information on treatments.
The Citrus Production Manual is available and for the month of April the price is reduced from $75 to $60! This is the first citrus manual in more than 20 years to cover all the major topics of citrus production including planting, horticulture, pest management and post harvest issues. It is a wonderful resource for all citrus producers and pest managers.
To order a copy, go to the UC Ag and Natural Resources catalog http://anrcatalog.ucanr.edu/ and type in publication 3539 or the search term 'citrus production manual' or call 1-800-994-8849.
Better yet, if you buy both the Citrus Production Manual and the IPM for citrus manual (pub 3539Promo) the combined price is only $85 - a savings of $30!
We usually hang traps for California red scale (CRS) the first of March at Lindcove REC and see the first flight start up a couple of weeks later. Not this year! The temperatures have been high and everything, including bloom is early. The CRS biofix for Kern was in late February and for Tulare foothills the first week of March. Unless we have an extreme downturn in temperatures, the first generation of crawlers will likely be early *in late April for Tulare). You can follow the general county accumulations of degree days weekly on our web site to get an idea of how fast things are progressing - California red scale degree days.
Come by and visit UC ANR booth 1512 in Pavilion A if you would like to talk about citrus pest issues. Beth Grafton-Cardwell, Sara Scott and Jennifer Ruvalcaba will be there. We have pest damaged fruit and several beneficials to display including Tamarixia, the parasitic wasp that attacks Asian citrus psyllid.
A number of Tulare County PCAs have observed a very dark thrips infesting the calyx and areas of the rind where fruit touch in mandarins this year. Samples were collected and identified by Dr. Mark Hoddle (Dept of Entomology, UC Riverside) as western flower thrips. We don't normally consider this thrips a pest of the rind of citrus. However, in some cases, a circular scarring was associated with the thrips feeding on the rind of the fruit. It is likely this is a rare event, precipitated by freeze and drought conditions. Should growers treat for this thrips? This decision has to be made based on each individual situation. The thrips have likely already done the damage and will be difficult to control with insecticides because they are tucked away. In addition, they will readily move to flowers when they become available.