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
Come one, come all - no reservations necessary. We are going to discuss the latest citrus thrips insecticide trial at Lindcove including walking in the orchard and looking at the level of thrips scarring. We will have a group discussion about the approaches being taken to manage citrus thrips in young and mature orchards.
Citrus Thrips Field Day at Lindcove
Tuesday, September 13, 2016
Lindcove Research and Extension Center
22963 Carson Ave., Exeter, CA 93221
(559) 592-2408 ext 151.
Instructor: Dr. Beth Grafton-Cardwell
Course Objective: To teach PCAs how to recognize the various life stages of citrus thrips and the predatory mites that attack them. A pesticide trial was conducted in April-May this year at Lindcove, and PCAs and growers will have the opportunity to look at the scarred fruit in that trial and examine the results.
9-9:30 a.m. Registration: Lindcove REC
A. Powerpoint presentation by Beth Grafton-Cardwell on efficacy of insecticides for citrus thrips control and resistance management
B. Microscope identification of citrus thrips life stages
C. Field discussion of citrus thrips and predatory mite monitoring methods and examination of the scarring damage in the experimental field plots.
Continuing Education 1.5 other units have been awarded
Various insects, birds, and other animals pollinate plants. Bees, especially honey bees, are the most vital for pollinating food crops. Many California crops rely on bees to pollinate their flowers and ensure a good yield of seeds, fruit, and nuts. Pesticides, especially insecticides, can harm bees if they are applied or allowed to drift to plants that are flowering.
Our mission at the University of California Agricultural and Natural Resources (UC ANR), Statewide Integrated Pest Management Program (UC IPM) is to protect the environment by reducing risks caused by pest management practices. UC IPM developed Bee Precaution Pesticide Ratings to help pest managers make an informed decision about how to protect bees when choosing or applying pesticides. You can find and compare ratings for pesticide active ingredients including acaricides (miticides), bactericides, fungicides, herbicides, and insecticides, and select the one posing the least harm to bees.
Ratings fall into three categories. Red, or rated I, pesticides should not be applied or allowed to drift to plants that are flowering. Plants include the crop AND nearby weeds. Yellow, or rated II, pesticides should not be applied or allowed to drift to plants that are flowering, except when the application is made between sunset and midnight if allowed by the pesticide label and regulations. Finally, green, or rated III, pesticides have no bee precautions, except when required by the pesticide label or regulations. Pesticide users must follow the product directions for handling and use and take at least the minimum precautions required by the pesticide label and regulations.
A group of bee experts in California, Oregon, and Washington worked with UC IPM to develop the Bee Precaution Pesticide Ratings. They reviewed studies published in scientific journals and summary reports from European and United States pesticide regulatory agencies. While the protection statements on the pesticide labels were taken into account when determining the ratings, it is important to stress that UC IPM's ratings are not the pollinator protection statements on the pesticide labels. In a number of cases, the ratings suggest a more protective action than the pesticide label.
The UC IPM ratings also include active ingredients that may not be registered in your state; please follow local regulations. In California, the suggested use of the bee precaution pesticide ratings is in conjunction with UC Pest Management Guidelines (for commercial agriculture) and Pest Notes (for gardeners). Each crop in the UC Pest Management Guidelines has a link to the Bee Precaution Pesticide Ratings database and provides guidance on how to reduce bee poisoning from pesticides.
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.