On September 30, an in-depth workshop was held at the UC ANR Lindcove Research and Extension Center to discuss the biology and management of California red scale. Twenty seven participants spent the day viewing scales under microscopes and learning about Aphytis and Comperiella wasps. The hot topic (literally) this year, above and beyond the usual complexities of managing scale, was the much higher than average accumulation of heat units. Normally there are about 4 generations of scale per year in the San Joaquin Valley, but this year a 5th generation is developing. This is the third year in a row that temperatures have been above the 30 year average. We also discussed the fact that systemic neonicotinoid insecticide use is becoming very common place and repeated use of the systemic neonicotinoids results in a build up of scale on the wood that is difficult to control with natural enemies or insecticides. So, the combined problems of scale build up due to changes in insecticide use patterns and high average daily temperatures have resulted in outbreaks of California red scale in the San Joaquin Valley.
At a recent meeting in Exeter, I discussed the Fuller rose beetle management plan for 2014. Research from 2013 demonstrated that two insecticide treatments per season were better than one. These treatments could be ground treatments or foliar. The ground treatment helps to keep emerging beetles from climbing the trunks and the foliar treatment kills them if they do reach the foliage. If two treatments are planned, early August and early October are the best time periods for the San Joaquin Valley. Choice of insecticide depends on application target and concerns about MRLs. Remember that skirt pruning in June and weed control are essential components of the Fuller rose beetle program. Korea may allow blanket fumigation or fumigation of infested loads with Methyl Bromide this year, but they are counting on California growers to apply in-field treatments to lower FRB populations. Methyl Bromide is not likely to be allowed in future years. Treating blocks several years in a row with foliar and/or ground treatments will help to bring the populations down to very low levels.
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.