- 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: Ben Faber
The University of California launched the Science for Citrus Health website to keep the citrus industry abreast of research currently being conducted to protect citrus from Huanglongbing. The site highlights research approaches, challenges and opportunities in a variety of areas that aim to provide mid- and long-term solutions to the disease.
check it out:
http://ucanr.edu/sites/scienceforcitrushealth/Research_Approaches/
- Author: Stephanie Parreira
UC Statewide Integrated Pest Management Program
According to the Centers for Disease Control and Prevention (CDC), poisoning is the number one cause of injury-related death in the United States, and 1073 people in California were poisoned by pesticides in 2014 alone. Each year since 1962, National Poison Prevention Week has taken place during the third week of March, to raise awareness about avoiding these tragedies. No one wants their workers or family members to experience illness or death from pesticide exposure, so the UC IPM Pesticide Safety Education Program (PSEP) would like to bring special attention to preventing pesticide poisoning this week. The program also published a new edition of The Safe and Effective Use of Pesticidesin 2016, which contains a wealth of pesticide safety and hazard prevention information for people who work with pesticides.
Both agricultural and household pesticides can poison people if they are not properly handled. In agriculture, poisoning most often results from pesticide mixing and loading, and the most harm occurs due to spills, splashes and equipment failure. In the home, many pesticide poisoning incidents involve children swallowing pesticides, including garden products, disinfectant cleaners, or other chemicals used to control pests.
One of the most important things you can do to prevent pesticide poisoning is to follow the instructions on the pesticide label. Labels address critical information about how to use a pesticide safely, including the kind of personal protective equipment (PPE) you should wear to prevent overexposure, how much of the product to apply, the minimum time you must wait to enter the area after applying the pesticide (the restricted entry interval), and the minimum time that must pass between application and harvest (preharvest interval).
Labels also include important signal words such as “Danger,” “Warning,” or “Caution” that indicate how acutely toxic the chemical is to humans, as well as directions to avoid pesticide contamination of sensitive areas such as schools and hospitals. These instructions are meant to protect anyone who is at risk of being exposed to hazardous pesticide residues. It is essential to thoroughly read and understand the pesticide label before working with the pesticide, and to carefully comply with label instructions throughout the process. The UC IPM guide to Understanding Pesticide Labels for Making Proper Applications can help you do this, and is available in both English and Spanish.
If you apply pesticides in or around your home, be sure to store them properly and keep them out of the reach of children. Keep in mind that even mothballs may look like candy to very young children. It is illegal and unsafe to store pesticides in food or drink containers, which can easily fool people into consuming them and being poisoned. According to the California Department of Pesticide Regulation, these mistakes caused 62 incidents of child poisoning from pesticide ingestion in California in 2014, and 47 of those cases involved children under six years of age.
To learn more about poisoning and how to prevent it, consider visiting the following resources:
Center for Disease Control and Prevention Leading Causes of Death Reports
National Poison Prevention Week website
National Pesticide Information Center
UC IPM online course: Proper Pesticide Use to Avoid Illegal Residues
- Author: Ben Faber
This is the abstract of a presentation that was made at the recent Huanglongbing Conference held in Orlando, FL. This and other paper abstracts will soon be available at: http://irchlb.org/files/33373ab0-7df3-4117-9.pdf
Spray application of different kaolin formulations on sweet orange plants disrupt the settling and probing behavior of Diaphorina citri
M. Miranda1, O. Zanardi1; H. Volpe1; R. Garcia1; N. Roda2, E. Prado3
1 Fundecitrus, Araraquara, Brazil, 2 Tessenderlo Kerley, Inc./NovaSource, Phoenix, USA, 3 Universidade Federal de Lavras, Lavras, Brazil.
Abstract: The psyllid Diaphorina citri is the vector of the bacteria associated with huanglongbing (HLB), which is the most destructive citrus disease worldwide. Chemical control is the primary tactic against this insect. However, alternative methods are important to achieve a more effective control in an integrated pest management programs. Thus, this research was carried out to assess the influence of different kaolin formulations on the settling and probing behavior of D. citri. In both studies, two wettable powder (WP) kaolin formulations (Tessenderlo Kerley, Inc./NovaSource) were sprayed three times at different concentrations on sweet orange plants. In the experiment to assess the settling behavior, three concentrations (3, 5 and 7% w/v) of both formulations were tested. A non-choice test was performed, where 16 adult psyllids were released in a cage with seedlings of the same treatment, and the number of psyllids/plant at different time intervals was counted. For the probing trial, the electrical penetration graph (EPG) technique was used. Adult psyllids were monitored for 6 h on nursery citrus trees treated with two kaolin formulations at 3 and 5% w/v. The two kaolin formulations have a repellent effect on D. citri, causing an overall reduction of 40% of psyllids settled on treated seedlings compared with untreated control. Moreover, both formulations disrupt D. citri probing behavior, with a significant reduction (60%) in the proportion of psyllids that reach the phloem compared with untreated nursery citrus trees. In general, there were no differences between the kaolin formulations and among the concentrations tested in both experiments (settling and probing). Then, both formulations could be used in an integrated D. citri management program. These findings reinforce the recommendation of kaolin application on young citrus planting as a useful strategy for HLB management, mainly on the edge of the farms.
Photo: ACP Feeding
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- Author: Ben Faber
A recent auction in South Africa was selling 'Maluma' variety of avocado for $92 a tree. That is more than the average price of avocado nursery trees in that country and a lot more than what is paid in California or Florida. That variety has suddenly gotten a huge demand because of its sales characteristics accounting for 13% of the tree sales from one nursery there.
This is a phenomenon that is going on world-wide not just for 'Maluma'. According to a CA nursery producer, the 'Maluma' sale is really a reflection of the world-wide demand for avocado trees and not necessarily this South African variety. Avocado acreage is expanding world-wide. So far 'Maluma' has a US import license, but has not been grown in CA, so we don't know its performance characteristics. That should change soon according to the nurseryman.
Related story: South Africa: Maluma Day to challenge avocado sector's “convenient position”:
http://www.freshfruitportal.com/news/2017/03/08/south-africa-avocado-auction-shows-exorbitant-demand-maluma-trees/