Junta sobre Manejo de Riego y Nutrientes 2022

Miércoles, 23 de Febrero

Registrar Reunión Virtual: https://surveys.ucanr.edu/survey.cfm?surveynumber=36536

Reunión Virtual Costo: $10.00
La información de inicio de sesión de Zoom se enviará más cerca de la fecha del evento

Para más información, contactar a:anrprogramsupport@ucanr.edu, 530-750-1361 (solo mensajes)

Habrá traducción al Español Enlace para

Crédito de Educación Continuada

CCA 3.5 créditos aprobados

CDPR 1.0 crédito de educación continuada pendiente

Para más información, contactar a Richard Smith, rifsmith@ucdavis.edu, 831-759-7353

Calendario

The Michelmore lab at the University of California, Davis routinely monitors isolates of Bremia lactucae, the pathogen that causes lettuce downy mildew for their ability to overcome disease resistance genes and for insensitivity to fungicides.  Isolates are currently being monitored for insensitivity to Revus, Forum, and Orondis. During 2021, 70 isolates were tested for growth on seedlings pretreated with 2 ppm Revus, 5 ppm Forum, or 0.5 ppm Orondis. Nearly all isolates were sensitive and showed no growth at these concentrations.  However, two isolates were insensitive to Forum and when retested, grew on 4 ppm treated seedlings. Another isolate was insensitive to Revus and could grow on seedlings pretreated with 3 ppm Revus when retested. All three isolates were collected in Oceano. No isolates have been detected that are insensitive to Orondis.  We are interested in receiving additional isolates from Oceano and other areas, particularly when there has been an apparent failure of control.  

Please see the attached for instructions as to how to send samples. 

Thank you for your help.

Richard Michelmore.

Distinguished Professor and Director 
The Genome Center
Genome and Biomedical Sciences Facility
451 Health Sciences Drive
University of California
Davis, CA 95616
rwmichelmore@ucdavis.edu
http://genomecenter.ucdavis.edu 
http://michelmorelab.ucdavis.edu

Please fill in as completely as possible.  This will help entry into the database but do not worry if some/most of this information is not available. 

Please include this datasheet when sending isolates.

Date Collected: ____/____/_____                                                          Collector ID: _________________

Collector: _______________________________                                            (UC Lab ID: _________________)

Location: _____________________________________________________________________________________________

GPS coordinates if known: ____________________________

Disease Intensity / Level of infection (circle one):   

                        Low (Few infected plants),

                        Intermediate (Infected plants scattered throughout field). 

                        Severe (Many infected plants)

Please comment whether collected from a single plant or from several plants and whether from multiple locations in the field.

Comments: __________________________________________________________________________________________________________________________________________________________________________________________________________________

Fungicide treatment:  Yes     No       Not known

        If yes:       Alliete          Ridomil          Revus         Orondis         Forum                                                Other:__________________

Type:   Crisphead       Romaine      Looseleaf       Butterhead       Babyleaf     Other:______________

            Cultivar/Variety: ____________________________________________________________________________

            Approximate planting/water date ________________________________________________________

Other Comments: _________________________________________________________________________________________________________

_________________________________________________________________________________________________________Thank you for your help.  Please address questions to Juliana Gill (giljuliana@gmail.com), and/or Richard Michelmore, rwmichelmore@ucdavis.edu.  

Results will be available from http://bremia.ucdavis.edu/bremia_database.php.

Collection and Shipping Instructions:

Please send leaves with fresh sporulating lesions.  These should be green or only slightly chlorotic: 

Please not send leaves with dark necrotic lesions; it is difficult to rescue isolates from such samples because of bacterial contamination: 

Please send overnight by Fed Ex (Account # 2630-4693-5) in a box rather than an envelope (to prevent samples being crushed) along with the datasheet and the words “Refrigerate upon arrival” on the outermost packaging to:

Attn: Juliana Gil

The Genome Center

Genome and Biomedical Sciences Facility

451 East Health Sciences Drive

University of California

Davis, CA 95616

Tel. 530-752-8889

Please notify Juliana Gil (giljuliana@gmail.com) with the tracking number when sent.

Please time the sending so that the isolate is not in the Fed Ex system over a weekend (i.e. do not send on a Friday).  Isolates can be kept in a fridge at 5^oC for a few days before sending if necessary, although sending samples immediately after collection is best. 

The California Chapter, American Society of Agronomy and Cooperative Extension, UC Agriculture and Natural Resources are hosting the annual Plant and Soil Conference on Tuesday, February 1 - Thursday, February 3.  This will be a virtual event using zoom. The Plant and Soil Conference is a great opportunity to increase your knowledge of crop production, soil and water management, and pest management as well as receive CCA and DPR educational hours.  The full agenda can be found here.   Registration is currently $90, but will increase to $115 on January 25th.  You can register for the conference at https://calasa.ucdavis.edu/Conference_Registration/.

Summary:Automated weeders are capable of selectively removing weeds from the uncultivated band (3-5 inches wide) left around the seedline by standard cultivation. A camera detects the image, a computer processes the image and then activates a kill mechanism (e.g. a split blade). Twelve evaluations of autoweeders were conducted in 2020-21. Autoweeders removed from 31.7 to 98.7% of the weeds (average = 69.5%). The percent of weeds removed by the autoweeders was affected by the width of the uncultivated band and by the use of transplants; autoweeders removed fewer weeds if the uncultivated band was narrower (e.g. 3 inches vs 4 inches); in addition, automated weeders worked more efficiently with transplanted lettuce because the crop and weeds were smaller when weeded. Autoweeders did not reduce the lettuce stand or mean head weight in any of these evaluations. Autoweeded fields generally require follow up hand weeding to remove double lettuce plants (in direct seeded lettuce) and any remaining weeds. The question that comes up for growers is, does the reduction in follow-up hand weeding pay for the cost of running the autoweeder the field? We were not able to provide a simple answer to this question, however, we did see greater reduction in the time to subsequently hand weed fields where an autoweeder was used when the initial weed population was higher. However, given the labor situation, autoweeders may be justified regardless, if hand labor is simply not available to weed fields.

Introduction: Automated weeder technology has evolved significantly over the past decade. The technology used by auto weeders is similar to that used by the auto thinners: cameras detect plants, a computer processes the image and makes decisions about which plants to keep and which to remove and then activates the kill mechanism. Automated weeders remove weeds from inside the uncultivated band (3-5 inches wide) left around the seedline and unreachable by standard cultivation.  The kill mechanism used by the currently available machines is either a split blade that opens around keeper plants (e.g. Robovator and Stout) or a spinning blade that avoids the keeper plants by placing them in a notch in the blade (e.g. Garford Robocrop).  Auto weeders do not remove all the weeds in the seedline because they cannot remove weeds that are too close to the crop plants without risking damaging them. In addition, automated weeders are currently not capable of removing double lettuce plants in direct seeded lettuce fields, and as a result, it is still necessary to have a crew pass through the field following the passage of the auto weeder to remove to remove double lettuce plants and any missed weeds. Therefore, there are two costs when weeding with an autoweeder: the cost of the automated weeder and subsequent hand weeding/double lettuce plant removal. If the auto weeders can reduce the amount of subsequent hand weeding to cover the cost of running the autoweeder, then it is a net gain for a grower. In these evaluations we examined the initial weed population and the reduction in subsequent hand weeding following the use of an autoweeder in order to better understand the impact of the use of autoweeders on weed control in lettuce production.

Methods: Twelve trials were conducted in 2020 and 2021. Table 1 shows the details about each trial: machine used, planting configuration, lettuce types and dates of operations. The FarmWise and Stout autoweeders used a split-knife kill mechanism and the Naio machine used finger weeders. Autoweeding was carried out after thinning (except Dino Trial No. 2 was cultivated prior to thinning) and were compared with standard cultivation which leaves a 4-5 inch wide band around the seedline. In 2020, pre and post cultivation weed and stand counts were made of a 6-inch wide band around the seedline to determine the efficacy of standard and auto cultivation, but in 2021, pre and post cultivation weed counts were made following the passing of the standard cultivation. Weeding time measurements were made of the time it took a commercial hand weeding crew to pass through the treatment rows which was then converted to hours per acre. Stand counts and harvest evaluations were conducted to determine if the auto weeders caused damage to the stand or to crop plants.

Results: The number of weeds in the seedlines varied from as low a 1.6 to as high 41.5 plants/m² (Table 2).  Autoweeders removed from 31.7 to 98.7% and averaged 69.5%. The percent of weeds removed by the autoweeders was affected by the width of the uncultivated band. For instance, in first 2021 FarmWise evaluation 69.0% of the weeds were removed; however, in the second FarmWise evaluation only 31.7% of the weeds were removed. We think the difference between these two trials is that the first evaluation had a 5-inch wide uncultivated band which include many weeds that were easier for the autoweeder to remove a large portion. However, in the second FarmWise evaluation the uncultivated band was 3-inches wide and many of the easy to remove weeds were already gone, thereby reducing the number of weeds available for the autoweeder to remove. In the first 2021 Stout evaluation 97.7% of the weeds were removed. This field was a transplanted field established with PlantTape. The lettuce plants and weeds were smaller at the time of weeding and the machine was able to operate extremely efficiently. Autoweeders were did not damage the lettuce stand or mean head weight in any of these evaluations (Table 3). The percent reduction in the amount of time to weed the field varied from 2.5 to 60.0% with the use of the autoweeders in comparison with standard cultivation. Autoweeders significantly reduced subsequent hand weeding in 2021 (Table 3). Figure 1 correlates initial weed populations with the amount of reduction in subsequent hand weeding. The correlation indicates that there is a greater impact on subsequent hand weeding with greater weed populations. As mentioned above, this correlation may be impacted by the width of the uncultivated band and by the use of transplants. In spite of these influences, it appears that automated weeders may have a greater economic impact on total weeding costs when there are higher weed populations.

FarmWise Titan

Stout Smart Cultivator

Naio Dino Weeding Platform