Web Author: Dr. Beth Grafton-Cardwell, conducts research in the San Joaquin Valley on insect and mite pests of citrus. These web pages provide up-to-date information about the pests and their natural enemies, including basic biology, hosts, distribution, monitoring methods and management tactics. Please join us in exploring this subject through blogs, information and resources.
Citrus Bugs Blog
Adult citricola scales are lining up on the twigs. Their eggs are hatching this month and crawlers are moving about on the twigs and settling on the leaves. Adults are hard to kill with insecticides and the eggs under their bodies are protected from insecticides. If you wait till all the eggs hatch and the crawlers move out onto the leaves, the insecticides will work better. Usually egg hatch finishes towards the end of July. You can check this by flipping over the female scales and looking to see if there are fresh eggs.
Cool wet springs favor egg hatch and survival of citricola scale, so be on your guard this spring. See the Citrus IPM Guidelines for Citricola scale for information on treatments. A new citricola scale-effective insecticide that will soon be added to the guidelines is Sivanto (flupyradifurone).
Dr. Grafton-Cardwell's research at Lindcove Research and Extension Center continues to look at the best use of Delegate, Sivanto, Movento, Exirel, Sevin and a number of unregistered insecticides for citrus thrips control. Technicians Sara Scott and Joshua Reger are using dual wands to hand spray trees. Results of this research will be available at the end of the summer when they evaluate the scarring of the fruit.
Similar to last year, degree days are accumulating rapidly this spring, well in advance of the 30 year average. This has an impact on the development of all insect pests. To see a comparison of current dd and 30 year average dd for California red scale, go to the UC KAC Entomology degree days for California red scale and click on any one of the four San Joaquin Valley regions. Below we show a Tulare County site as an example. You will see that the biofix was earlier than normal (early to mid March) and the current degree days for that insect are >100 dd farther along than the 30 year average. This is the fifth year in a row (2012-2016) we have had this situation of rapid degree day accumulations, which accelerates the development of the insect.
In addition, I have also heard that in the southern end of the San Joaquin Valley, the crawlers were emerging before the 550 degree day mark, which means that, for the second year in a row, we did not have cold enough temperatures to cause California red scale to diapause. This makes timing insecticide treatments extremely difficult because the scales are not developing uniformly and the window of crawler activity is very wide. The extra degree days allows extra generations of California red scale to develop. Most of the available red scale insecticides are not persistent enough to control more than one or two generations. Starting last year, some growers began treating more than once per year for red scale.
Its hard to say if this pattern will continue, but cooler winters and springs would help immensely with California red scale control.
—Cheryl Reynolds, UC Statewide IPM Program
Are you looking for continuing education units (CEUs) to complete your renewal application this year for the Department of Pesticide Regulation (DPR)? The UC Statewide IPM Program and the Lindcove Research and Extension Center have several online courses available that can help you get those last few needed credits. All courses can be found on the UC ANR Learning Management System. Be sure to spend at least 1 hour on each unit to receive credit.
DPR license and certificate holders with last names beginning with M – Z renew this year. Renewal packets must be submitted to DPR before November 19th to ensure that licenses are renewed by January 1, 2016. After that, applications may take up to 45 calendar days to process.
The online courses available from UC IPM that offer units for DPR license renewal include:
- Providing Integrated Pest Management Services in Schools and Child Care Settings (1 unit Laws and Regulations and 1 unit Other)
- Pesticide Resistance (2 units Other)
- Pesticide Application Equipment and Calibration (1.5 units Other)
- IPM – A Solution for Reducing Pesticides/Water Quality: Pesticide Properties (1 unit Other)
- The Impact of Pesticides on Water Quality/Mitigating Urban Pesticide Runoff (1 unit Other)
- Water Quality and Mitigation: Bifenthrin and Fipronil (1 unit Other)
- Herbicides and Water Quality (1 unit Other)
Six additional courses on key pests of citrus are also available for DPR units and were developed by Beth-Grafton Cardwell from the Lindcove Research and Extension Center. These include:
- California Red Scale (1 unit Other)
- Citricola Scale (1 unit Other)
- Citrus Red Mite (1 unit Other)
- Cottony Cushion Scale (1 unit Other)
- Forktailed Bush Katydid (1 unit Other)
- Citrus Peelminer (1 unit Other)
For a list of other approved online or in-person courses, visit the DPR website. UC IPM plans to add additional online courses for 2016, including those available for Laws and Regulations units. For more information about the courses UC IPM offers as well as additional training opportunities and pest management information, see the UC IPM web site.
Understanding Pesticide Labels for Making Proper Applications
The UC Statewide Integrated Pest Management Program (UC IPM) put together a 26-page card set in English and Spanish on understanding pesticide labels. Intended for pesticide handlers, applicators, safety trainers, and pest control advisers (PCAs), the cards explain when to read the label, describe what kind of information can be found in each section of a pesticide label, and point out specific instruction areas so that applicators can apply pesticides safely and avoid illegal pesticide residues.
Traces of pesticide residue are normal and even expected after pesticides are applied to food crops, but by the time produce is ready to be sold, purchased, and consumed, residues are usually far below the legal limit.
In its latest report from 2013, the California Department of Pesticide Regulation (DPR) reported that there was little or no detectable pesticide residue in 97.8% of all California-grown produce. This demonstrates a strong pesticide regulation program and pesticide applicators that apply pesticides safely and legally. However, there have been instances in California where a pesticide not registered for a specific crop has been used unintentionally, resulting in illegal residues and eventually crop loss and destruction.
The Environmental Protection Agency (EPA) sets tolerances for the maximum amount of pesticide residue that can legally be allowed to remain on or in food.
DPR regularly monitors domestic and imported produce for pesticide residues and is considered the most extensive state residue-monitoring program in the nation.
The primary way pesticide applicators can assure that they make proper applications and avoid illegal pesticide residues is to follow the pesticide label. UC IPM's new card set was developed from information in the upcoming third edition of The Safe and Effective Use of Pesticides as well as Lisa Blecker, UC IPM's Pesticide Safety Education Program coordinator. Bound with a spiral coil, this eye-catching instructional card set was designed for both English-speakers and when flipped over, for Spanish-speaking audiences as well. UC IPM also plans to release a new online course on preventing illegal pesticide residues sometime late fall.
To download copies of the card set in English or in Spanish, see the UC IPM web site.