- Author: Ben Faber
The avocado is an odd duck in many ways and notably in its flowering. It has a complete flower, meaning it has both male and female parts in the same flower. Some plants have separate male and female flowers on the same plant and other species have male plants and female plants. The avocado, though acts – or is supposed to act – as if it had different stage flowers at different times. It opens as a female (stamens up), then closes and the same flower then opens as a male (stamens splayed out). They open separately in time, so, in theory, they cannot pollinate themselves – transfer pollen from the stamen (male part) to the pistil (female part). Fertilization occurs when the pollen tube grows down the stigma to the ovule and initiates a fruit – avocado sex. This is called synchronous (in a time sequence) dichogamy (split marriage). This is further complicated by having A and B flower types, where there are different lengths of time that the sexual stages are in flower. You can read more about it here:
http://ucavo.ucr.edu/Flowering/FloweringBasics.html
The problem is that the avocado hasn't read the text book about how it is supposed to flower and who or what transfers the pollen between the male and female stages. The flower can often open as a female and be that way for days and there won't be a single male flower around, or be in a male stage for days and no female. Or sometimes you find some females open and some males and sometimes that follow a time sequence where female may be open in one part of the day and males at another. If the varieties near each other are complementary (pollinizers), some having more females than male flowers and the other tree having more male flowers than females, there can be transfer of the pollen……. if the pollinator is around – a honeybee, native bee, hover fly, fly, wasp, thrips a myriad of potential agents. And if the weather right, and pollen is transferred to the female stage, it's possible there might be fertilization and fruit set.
So, the avocado is in full bloom through much of the avocado growing areas of California. And if you look out at the hives placed in the orchard you may not see any honeybees on the trees. Is that because they aren't flying? The weather is too cool? Because the flowers are in a male stage and they don't want pollen as a source of protein? Is there some other more attractive flower in the area? Do they no like the avocado nectar with its high sucrose and perseitol content?
What is going on? That is my question to you, dear readers? What are you seeing in your orchards? What insects are on the avocado flowers? What temperatures and time of the day are they flying? In what stage are the flowers, male or female? Are you seeing fruit set?
And while you are at it, what birds are you seeing in the orchard? How many different species? Typically there are hummingbirds nesting in avocados this time of year.
Go ahead and make your comments on line here.
Photo: Male and Female Stage Flowers
- Author: UC Statewide IPM Program
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.
For more information on protecting bees from pesticides, see UC IPM's Protecting Natural Enemies and Pollinators, and use the Bee Precaution Pesticide Ratings.
Bee Guide
“According to a UC Berkeley news report,about one-third of the value of California agriculture comes from pollinator-dependent crops, representing a net value of $11.7 billion per year.”
- Author: Ben Faber
By: Carey Gillam, Reuters
Honey bees, critical agents in the pollination of key U.S. crops, disappeared at a staggering rate over the last year, according to a new government report that comes as regulators, environmentalists and agribusinesses try to reverse the losses.
Losses of managed honey bee colonies hit 42.1 percent from April 2014 through April 2015, up from 34.2 percent for 2013-2014, and the second-highest annual loss seen, the U.S. Department of Agriculture said in a report issued on Wednesday.
"Such high colony losses in the summer and year-round remain very troubling," Jeff Pettis, a USDA senior entomologist, said in a statement.
The 2014-15 yearly loss was down slightly from the 45 percent annual loss for 2012-2013 but well above the prior two years of annual measurements and above the benchmark of 18.7 percent that is considered economically unsustainable, USDA said.
Millions of honey bees are relied on to pollinate plants that produce a quarter of the food consumed by Americans. Beekeepers travel the country with managed hives to help the process.
But over the past few years, bee populations have been dying at a rate the U.S. government says must be addressed, and finding an answer has become a politically charged debate.
Beekeepers, environmental groups and some scientists blame a class of insecticide known as neonicotinoids, or neonics, used on crops such as corn as well as on plants used in lawns and gardens.
But Bayer, Syngenta and other agrichemical companies that sell neonic products say many factors such as mite infestations are harming the bees.
The White House has formed a task force to study the issue, and some lawn and garden retailers have been cutting use of neonics.
The Environmental Protection Agency is requiring a series of studies on neonic effects on bees and plans to issue the first of a series of assessments later this year.
The USDA report issued on Wednesday said colony losses were 23.1 percent for the 2014-15 winter months, typically the higher loss period. The 2014 summer loss of 27.4 percent marked the first time summer losses exceeded winter, and marked a surge from the 2013 summer loss of 19.8 percent, USDA said.
The results are considered preliminary and are based on survey responses from about 6,100 beekeepers managing 400,000 colonies, USDA said. Those beekeepers represent nearly 15.5 percent of 2.74 million U.S. bee colonies. A more detailed report is to be published later this year, USDA said.
- Author: Ben Faber
Gordon Frankie a bee biologist at UC Berkeley and I are doing a study to ultimately identify what plants could grown in avocado orchards to attract more honeybees, as well as other pollinators and potential biocontrol agents. There are five orchards in Ventura and Santa Barbara where we have been monitoring flower visitation by different insects in order to get a baseline of what is there before introducing potential pollinator/biocontrol attractants. The numbers are finally in for last spring avocado bloom. Virtually no honeybees, but significant numbers of syrphid flies. They are also called flower flies or hover flies. They superficially resemble bees. They are predatory as larvae, primarily feeding on aphids. Then they become important pollinators as adults. They are not as efficient as honeybees because they lack all the hairs on their bodies where pollen gets stuck and carried to female flowers. The cause of the honeybee decline has many causes, but the most likely one is the drought in the avocado growing areas. There just aren't any plants in the foothill areas to provide pollen and nectar year round.
Images of egg, larvae (going after aphids) and adult syrphid flies
- Author: Ben Faber
Two years ago we set out to study the impact of native bees on avocado fruit set. We applied for several grants unsuccessfully and turned to growers to see if there was interest. We raised $6,000 to start the project and have established 4 sites in Ventura and Santa Barbara counties. in the meantime have gotten a Sustainable Agricultural Research and Extension grant. This grant does not start until October 2014. We need bridging funds to continue this study. Below is the original request from growers for funds. If you would help contribute it will keep this study going until the larger grant comes through. Thank you.
Dr. Gordon Frankie at UC Berkeley is teaming with Dr. Ben Faber from the Ventura County UCCE Extension to jointly work on a pollination study for avocados. Dr. Frankie is studying how to increase native bee pollinators in avocado orchards. To do this, we plan on surveying the native bees that are in the area, identify the plants that they are foraging on and then plant those species in orchards to lure indigenous bees + pollinators in to the orchards. These plants will also be monitored for their attractiveness to beneficial insects which could control avocado thrips, persea mite along with other pests. We will need some startup money to cover the costs of native plants plus travel for Dr. Frankie and his assistant to be able to come down to monitor the project. They are ready and willing to come do this important study. We have applied for UC grants and will apply to CA Avocado Commission and CDFA Specialty Crops for money, but we will not see that money until summer 2014 at the earliest. We need your help. It would help to plant the natives before the winter rains. They need the rain to bloom; so the sooner you can help, the sooner we can plant. We are trying to cobble together donations of about $3,000. Thank you in advance. Any contributions are tax deductible and can be made to: UC Berkeley Foundation (with a notation at the bottom of the check: Gordon Frankie Bee Lab) and sent to Dept of Environmental Sciences, UC Berkeley, 130 Mulford Hall #3114, Berkeley, CA 94720.