- Author: Ben A Faber
Greening Bacterium Causes Changes in Psyllids
Recent studies, including a partnership project between Fundecitrus and the University of California, revealed that the citrus greening bacterium Candidatus Liberibacter asiaticus causes physiological changes in psyllids, posing additional challenges to management strategies. An increase in the number of eggs, more frequent dispersal flights over longer distances and greater attractiveness to the host are some of the changes observed in infected psyllids.
MORE DIFFICULT TO MANAGE
“Epidemiologically speaking, the changes we have been observing in psyllid behavior turn it into a much more problematic insect,” said Fernando Amaral, Fundecitrus agricultural engineer and post-doctoral student at the São Paulo University Luiz de Queiroz College of Agriculture.
The psyllid behavioral changes hinder the development of pheromone tools to attract the insect and improve its monitoring.
“It is becoming increasingly clear that the psyllid undergoes several changes, and this phenomenon not only poses difficulties to management, but also curbs the development of products to capture the insect,” added Fundecitrus researcher Haroldo Volpe.
Studies published between 2015 and 2024 revealed that psyllids infected with the greening bacteria can lay up to 100% more eggs than healthy insects, contributing to the growth of the psyllid population.
FREQUENT FLIERS
The studies also concluded that infected psyllids are more agitated when compared to healthy insects. In order to reach this conclusion, researchers placed adult insects from both groups on a platform. The teams noticed that infected insects flew, on average, after 50 seconds from the beginning of the observation period. The healthy subjects took around 150 seconds.
“Knowing that the insect flies more often and starts flying earlier demonstrates agitation and altered behavior, increasing its ability to spread greening,” said Volpe.
Yet another conclusion of the studies is that infected psyllids perform more frequent dispersal flights.
“Psyllids infected with the greening bacteria have a 45% higher rate of long flights when compared to healthy insects,” said Amaral.
In other words, the infected psyllid will fly longer distances and further spread the disease. Moreover, infected psyllids will also have a greater need to feed (forage) on more shoots and consequently will further disseminate the disease.
SUSCEPTIBILITY TO INSECTICIDES
On the other hand, the susceptibility of infected insects to insecticides is greater than that of healthy insects. Psyllids infected with the greening bacteria require a 20% to 313% lower concentration of insecticides to achieve the same mortality rate as healthy insects. This happens because the bacteria interferes with the psyllid metabolization of these products, which hinders their detoxication process.
CONTINUE COMBATING DISEASE
Fundecitrus General Manager Juliano Ayres emphasized the need for citrus growers to remain aware of the measures used to combat the disease in the field.
“The more diseased plants in groves without appropriate psyllid control, the more contaminated insects there will be and, consequently, the faster the disease will spread,” Ayres said. “Therefore, it is essential to continue to eliminate diseased plants from groves and keep up strict control of the insect on these plants.”
Source: Citricultor, Fundecitrus
CLas-Positive Psyllid Sample in Riverside County
July 26, 2024
An adult Asian citrus psyllid (ACP) sample from a residential property in the San Jacinto Valley area of Riverside County, California, has tested positive for Candidatus Liberibacter asiaticus (CLas), the bacterium that causes huanglongbing (HLB).
The positive sample was collected as part of the Multi-Pest Risk Survey on a residential property in Hemet. It was confirmed positive for CLas on July 17 by the Citrus Research Board's Jerry Dimitman Laboratory. Nymphs were also collected from the property and tested negative for CLas. This is the first confirmed CLas-positive adult ACP found in the San Jacinto Valley area.
An HLB quarantine zone will not be established as a result of this CLas-positive ACP detection. However, California Department of Food and Agriculture (CDFA) staff is conducting surveys and collecting samples from the property and all HLB host plants that are located within a 250-meter radius around the find, per the ACP/HLB Action Plan.
It is crucial that ACP populations continue to be controlled properly in order to stop HLB from spreading, advised California's Citrus Pest & Disease Prevention Program.
While CDFA is not requiring mandatory treatment for area commercial growers, those who wish to take proactive steps to protect their groves or who have additional questions can contact Riverside County Grower Liaison Sandra Zwaal.
In September 2023, a CLas-positive ACP sample was collected from a residential property in California's Ventura County. That sample came from a residential citrus tree in the southwest area of Santa Paula. An HLB quarantine zone was not established as a result of that detection, either. While that first confirmation of a CLas-positive ACP in Ventura County was concerning, HLB was not detected in any Ventura County citrus trees. Learn more here.
Source: Citrus Pest & Disease Prevention Program
- Prepared by: Terry Lewis
Tasks
- Check drip emitters to adjust flow and unclog them if needed.
- Lightly trim lavenders after they have finished flowering to keep them compact.
- Support any heavily laden branches of fruit and nut trees.
- Water citrus being careful not to overwater. Continuously wet soil in the upper few inches risks root rot.
Pruning
- Deadhead roses, remove suckers and unwanted branches, and prune to improve air circulation.
- Divide iris every 2 or 3 years and replant new rhizomes.
Fertilizing
- Lightly fertilize annuals and roses for fall bloom.
Planting
- Any planting this month (including trees and shrubs) will require adequate water and sun protection.
- Bulbs, corms, tubers: Watsonia.
- Fruits and vegetables: lettuce, mustard, peas, potatoes, spinach, Swiss chard, turnips (plant from seed).
Enjoy now
- Annuals and perennials: petunia, annual phlox (Phlox drummondii), moss rose (Portulaca), sage (Salvia), Stokes' aster (Stokesia), verbena, zinnia.
- Bulbs, corms, tubers: lily (Lilium asiatic hybrid).
- Trees, shrubs, vines: desert willow (Chilopsis), rose, chaste tree (Vitex).
- Fruits and vegetables: cantaloupe, plum, tomato, tomatillo, squash.
Things to ponder
- Do not allow vegetables to dry out - but do not over water either. A consistent, even supply of moisture prevents bitterness in cucumbers and cracking and poor fruit quality in tomatoes.
- Standing water, even in the very smallest container, can be a breeding ground for mosquitoes.
- Browse fall catalogs to order seeds and bulbs for winter and spring.
- Author: Kathy Keatley Garvey
He's a male Mantis religiosa, as slim as a string bean, and scanning his environment.
We're accustomed to seeing see the native Stagmomantis limbata in our garden, and not M. religiosa, the European mantis, which is found throughout Europe, Asia, Africa, and North America.
"Males are often found to be more active and agile, whereas females are physically more powerful," according to Wikipedia. "Adult females are generally too large and heavy for their wings to enable a take-off...The great variation in the coloration of M. religiosa from different shades of yellow, brown, green, and sometimes black has been the cause of numerous hypotheses and studies for over 100 years.However, no generally accepted answer about reason, benefit, or mechanism of the coloration or the change of coloration has been found."
The male is apparently quite good at avoiding sexual cannibalism during mating. Wikipedia says: "Instead of just observing them, sexually mature males approach sexually mature females when they see them, but due to the physical superiority of the females, males of M. religiosa face certain challenges in doing so. When a female spots a male, she is very likely to attack and kill him (see also: Sexual cannibalism). Therefore, males can be observed to be very slow and cautious in their approach; after spotting a female, the male usually freezes and turns his head to look directly at her. Since the foveae in his eyes face directly forwards, he has the most accurate and detailed view of her and can watch every one of her moves. He then proceeds to approach her from behind. Males can be observed to stop as soon as the female turns her head or even moves. Mantids are very good at detecting moving structures, but are almost unable to see immobile objects. Using this ‘stop-and-go' tactic, the male stalks closer to the female. This can often take several hours. Depending on the environment, males sometimes show a light ‘rocking'-behavior which is believed to imitate the leaves of surrounding plants to blend in with the background. Males doing this had no higher probability of being detected and attacked, which supports this hypothesis of concealment."
We asked praying mantis scientist Lohit Garikipati about this European species. He holds a bachelor's degree from UC Davis and a master's degree from Towson University, Md., and is now PhD-bound at the Richard Gilder Graduate School in the American Museum of Natural History in the Jessica Ware lab.
"In my time at Davis I observationally did--they hold a special place for me as they were the first species that ever kept and raised in captivity!" said Garikapti, who shared his mantises and expertise at the Bohart Museum of Entomology open houses. "But they also highlighted to me the potential impact of invasive species on both native mantis species but also prey populations--as low foliage and ground dwelling predators, they have a different niche from S. limbata, and may be contributing to the decline of native Litaneutria (even as they have for the California mantis, Stagmomantis wheelerii). Adult females have also been observed feeding on fence lizards, without much apparent effort as they can take lizards even larger than they are. All of these factors combined with their cryptic ooth (ootheca) deposition and large clutch size have made them one of the most if not the most successful mantis species on the planet - they tolerate both cold and hot climates being found in deserts to temperate forests and now have a Holarctic distribution."
Garikipati related that in the Ware lab, he will be "investigating the evolutionary relationships of praying mantises and what drove their diversity."
We look forward to hearing more from Lohit! As for our buddy, the male M. religiosa, he took flight. (See video on YouTube).
- Author: Luis A Espino
In the last two weeks, I visited a couple of fields suspected of having blast. After looking at the symptoms and the distribution of the lesions in the field, we determined that the injury we were observing was most likely due to herbicide burn. When blast lesions coalesce, they can look a lot like herbicide burn, but with blast you will find some of the typical diamond shape lesions. Also, when blast results in burned holes, you will find a lot of blast lesions around the hole that decrease in density as you move away from the hole.
Herbicide burn that can be confused with blast |
Typical blast diamond shaped lesions |
I have not seen blast lesions this year yet. Looking at leaf wetness and temperature at the field level, we had some good conditions for blast around July 20. This is only an approximation and does not necessarily mean that we will see blast. Remember that two more things are needed to see infections: a susceptible host and the pathogen. Most of our varieties are susceptible, with only M-210 being resistant. At this point we do not have a way to monitor for the presence of the pathogen in the Valley other than by detecting infected fields.
Hours of leaf wetness (LW) required for infection (blue line) and total hours of leaf wetness (orage line). When the orange line intercepts or is higher than the blue, there is enough hours of leaf wetness for blast infection.
I'll keep monitoring and let you know if I see blast in the field.
/table>The UC Master Gardener Program 2024 Reappointment window has now closed! Per the UCCE Master Gardener Program Administrative Handbook the reappointment window Jun. 1, 2024 - July 31, 2024
At this stage, we begin:
- Notifying volunteers who have not completed reappointment of a forthcoming change intheirstatus
- from Active or Limited Active to Inactive-Resigned
- from Active or Limited Active to Honorary
- Collecting insurance payments (at a rate of $6.00 per volunteer)
- Preparing to receive an invoice from the statewide office requesting recharge for insurance payments made on behalf of the county program (at a rate of $6.00 per volunteer)
Reappointment Guides and Templates
Help documentation and training resources, including Step-by-Step Guides to Reappointment and Template Letters to Inactive-Resigned volunteers, can be found on the UC Master Gardener Coordinator website's Reappointment page.
Insurance Invoices
We recommend blocking out a few hours through the end of August 2024 to ensure that your reappointment is complete and that insurance fees are properly submitted to the UC Master Gardener Program statewide office. Counties will receive insurance billing information beginning the first week of August. Insurance payments will draw from recharge account numbers provided by coordinators. This year, we are working with new account strings. Please be prepared to verify the account string on your invoice using this KFS to AE Account Look-Up file prepared by BOC. Alternatively, checks can be made payable to UC Regents.
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