- Author: Michael D Cahn
Habrá traducción al Español!
Where: This is an online virtual event
Monday November 27, 1-3 pm Session 1 Understanding nitrogen and soil organic matter
Monday, December 4, 1-3 pm Session 2 Compost, fertilizers and cover crops
Monday December 11 , 1-3 pm Session 3 Water, synchronizing demand and supply
Monday December 18, 1-3 pm Open house, Grower panel
Note: Limited to 80 participants -- Must enroll in all 3 classes (Session 1-3)
Cost $25 No one will be turned away due to lack of funds. Please email Rob Straser with questions (rkstraser@ucanr.edu).
Earn 6 hours of CDFA-INMTP continuing education credits (formerly CURES CE Credits)
Earn 6 hours CCA credits
About this workshop
In this 3-part series, participants will learn how to estimate nitrogen release from diverse organic sources and translate that knowledge to nitrogen fertilization plans and regulatory reporting requirements. In session 2 and 4, participants will be able to work on and receive feedback on their own nitrogen budgets. Over the first 3 sessions, we will cover the most common sources of nitrogen and complete a nitrogen budget.
Who should enroll?
Growers, CCAs, PCAs and other agricultural professionals who are interested in learning about nitrogen management in organic production are encouraged to enroll.
November 27, 2023, 1-3 pm Part 1: Understanding nitrogen: the nutrient, the role of microbes and the relevance of soil organic matter
Presenters: Daniel Geisseler, Radomir Schmidt and Margaret Lloyd
We will begin with an overview of the sources, transformations and fates of sources of organic nitrogen in soil. Foundational to this, we'll cover the role and dynamics of microbes in nitrogen management, and how that impacts management decisions. Lastly, we'll discuss using nitrogen budgets to understand the sources and proportions of available nitrogen to meet crop demand.
December 4, 2023 1-3 pm Part 2: Estimating nitrogen release from organic amendments and contributions from cover crops
Presenters: Patricia Lazicki and Margaret Lloyd
This session will focus on estimating nitrogen release from compost, organic fertilizers and cover crops. In addition, participants will be invited to apply the training to their own operations and receive feedback on the budget calculations during this session.
December 11, 2023 1-3 pm Part 3: Putting it all together: Completing a nitrogen budget, synchronizing nitrogen release with nitrogen demand, and using soil tests
Presenters: Daniel Geisseler, Joji Muramoto, Michael Cahn and Margaret Lloyd
In this session, we will address specific aspects of organic soil fertility management in vegetables. Discussions will include nitrogen in irrigation water, managing water for nitrogen optimization, crop nitrogen demand and strategies to supply demand, as well as using and interpreting soil testing. Specific references will be made to strategies for complying with forthcoming regulations. We will conclude with a discussion on new frontiers in plant's nitrogen acquisition science.
December 18, 2023, 1-3 pm part 4: Open house (Grower Panel)
In this session we will have 1-2 growers share their experience managing nitrogen on their farms. Then, we will open it up to questions, share experiences and discuss the nitrogen budget file. Attendees will be encouraged to bring their own data to receive feedback.
About the Presenters
Daniel Geisseler is an associate Cooperative Extension Specialist in the Department of Land, Air and Water Resources at UC Davis. Daniel's research and outreach focuses on nutrient turnover and plant nutrition in agricultural systems. He is interested in the effects that different management practices have on nutrient use in California crops and how nutrient use efficiency can be improved, particularly with nitrogen. |
|
Patricia Lazicki is the Vegetable Crops Advisor for Yolo, Solano, and Sacramento Counties, working mainly in tomatoes. Her research interests include soil health, and nutrient management and fertility in organic annual cropping systems. |
|
Margaret Lloyd is the Organic Agriculture and Small Farms Advisor for Yolo, Solano and Sacramento Counties. She runs an active research and outreach program focused on nutrient management and pest management for organic vegetable farms. |
|
Joji Muramoto (joji@ucsc.edu) is an assistant Cooperative Extension organic production specialist at UC Santa Cruz. His research and extension focus on nitrogen and soilborne disease management in organic cropping systems across the state. |
|
Radomir Schmidt is a program manager at the Working Lands Innovation Center at the UC Davis Institute of the Environment. As a soil microbiologist, Radomir conducts research on the effects of specific farming practices (organic amendment application, enhanced rock weathering, cover cropping, no-till systems) on carbon sequestration and greenhouse gas fluxes in soils, and on the the roles of microbial communities in soil health improvement and maintenance. |
|
Michael Cahn (mdcahn@ucanr.edu) is an irrigation and water resources Farm Advisor for UC Cooperative Extension in Monterey County. His research and extension program focuses on irrigation efficiency, nutrient use of crops, and protecting water quality. He led the development of CropManage, an online decision support tool for irrigation and nutrient management. |
/table>
- Author: Kirsten Ann Pearsons
“In the coastal areas where spotted wilt is a serious problem ... there is much to be learned concerning the seasonal migrations and local host succession of the thrips”
At first, this looks like a quote from 2020 or 2022 made in reference to the recent outbreaks of Impaciens necrotic spot virus (INSV), a thrips-transmitted disease currently affecting lettuce. But the quote is actually pulled from a UC publication titled Thrips of economic importance in California, authored by Professor Stanley Bailey in 1938.
The lettuce industry here in the Salinas Valley has been hit hard by INSV the past few years, and understanding the biology of the thrips that vectors the virus could be critical for management. But as Bailey noted almost 100 years ago, fully understanding the biology of western flower thrips has been elusive for decades.
In Thrips of economic importance in California, Bailey also noted that thrips in coastal areas tend to spend their summers at higher altitudes, but as native hosts dry up, they can concentrate on nearby crops. I wondered if such a migration could help explain the increase in thrips and INSV pressure the past few falls. With advances in thrips collection methods (i.e., sticky cards) and changes in cropping patterns, I was curious -- could we could observe the migration that Bailey described nearly 100 years ago?
Methods: With help from John Massa (Comgro) and a team from Braga Fresh (Eric Morgan, Katie Chiapuzio, and Jaylen Calabro), I set up a loose transect of 10 sticky card traps at about 4' off the ground (Figure 1). The transect spanned 0.38 miles (610 m) and an elevation change of 325 ft (99 m).
The first traps were deployed on June 5th and the last traps were collected on October 25th. We swapped out cards every two weeks for a total of 10 sets of cards. Some cows used two of the lower traps as scratching posts, so we were limited to 8 traps for most of the trial.
Sticky cards were taken back to the lab to count any thrips that fit the general description of Western flower thrips, Frankliniella occidentalis: less than 2 mm long, overall yellow to brown body color. Some larger, black thrips were occasionally found on traps and were excluded from overall counts.
Hypothesis: Thrips migrate down from the hills in late summer and early fall, increasing the thrips pressure in the valley which could increase the risk of spreading INSV.
Expected Results: If thrips counts are high in the hills in summer, but drop as populations rise in the valley, then this would be good support for Bailey's note and my hypothesis (Figure 2A). Alternatively, if thrips populations in the hills are consistent across time (Figure 2B), or if their population fluctuations match what is going on in the valley (Figure 2C), then it is unlikely that a mass migration is occurring.
Results: The transect results are summarized in figure 3. In panel A, the average thrips per week is plotted over time, with cards grouped by location (top of the hill, middle of the hill, or towards the bottom). The bottom traps were mostly surrounded by dried grass, while the top and middle traps were generally near chaparral plants that stayed green and flowering throughout the summer and into the fall. You can see an increase in thrips captures from June into July, followed by a dip in early august, and two more peaks in mid-August and early October (following that three-day heatwave). Compared to the valley counts (red line), the number of thrips captured on the hill was much higher, an average of 13 times higher than in the Valley. Adjusting the scale of the Valley-level trap counts (Figure 3B), we can see the Valley traps somewhat followed a similar pattern - thrips populations peaked in early June, had a few weeks of low counts in early August, then peaked again in mid-August and early October. With some variation, adult thrips captures in the hills followed a similar pattern to those captured nearby in the Valley.
Preliminary Conclusions: Contrary to my hypothesis, this small study does not provide evidence that thrips migrate en masse from the hills into the Salinas Valley. The hills maintained some green vegetation and flowers throughout the year, so thrips may not be driven to the Valley like Bailey described. Instead, the hills supported high thrips population throughout the summer and into the fall, which may have acted more like a continuous source of thrips into the valley. This could have interesting effects on INSV epidemiology, depending on whether the host plants in the hills can acquire INSV.
We of course cannot rely on a single transect in one year to conclude that thrips never migrate en mass into the Valley. This year we had an atypical, cool, wet spring that may have changed if or how thrips migrate. Perhaps migration only occurs in years with a drier, warmer spring. We also cannot discount the fact that the thrips we counted may not all be Western flower thrips; the identification characteristics we used (less than 2 mm long, overall yellow to brown body color) are not diagnostic of Western flower thrips. The next steps in this study would be to set up additional transects next year and live collection of thrips off of vegetation. By setting up additional transects (and getting them set up earlier in the season), we could determine if this preliminary transect was an anomaly, or if thrips are not behaving the way that Bailey described in 1938. Live collection of thrips is necessary to determine what proportion of thrips in the hills are Western flower thrips that can vector INSV. Either way, we are one step closer to understanding the seasonal migrations and local host succession of thrips, which could help us in our fight against INSV.
Much thanks to John Massa, Eric Morgan, Katie Chiapuzio, Jaylen Calabro, Jasmine Rodriguez, Luis Ramirez-Espinoza, and Carlos Rodriguez Lopez!
- Author: Kirsten Ann Pearsons
We are getting to the time of year where lettuce production winds down in the Salinas Valley and ramps up in the desert around Yuma, Arizona. Unlike in the Salinas Valley, the desert has not been hit as hard by Impaciens necrotic spot virus (INSV), the virus that is transmitted to lettuce by Western flower thrips (F. occidentalis). When the virus does show up in the desert, the primary infection can often be traced back to INSV-infected thrips that arrived on vegetable transplants from coastal California (Palumbo, 2022)
These finding stirred up concern in the local ag community – could vegetable transplants also be a significant source of new INSV infections in the Salinas Valley? There are instances where recently transplanted fields start showing INSV symptoms soon after planting (Figure 1), but it is challenging to nail down if they were infected before or after transplanting. After gaining some advice from John Palumbo of the University of Arizona (who has been spearheading the ISNV work in the desert), I set out to sample thrips from local transplant nurseries.
Hypothesis: Vegetable transplants are NOT a major source of INSV-infected thrips in the Salinas Valley. Although this hypothesis may seem contrary to the findings from Yuma, it all comes down to timing of transplant production and background levels of thrips and INSV. As summarized in Figure 2, weekly thrips activity is low in spring and early summer but high in late summer and early spring. [check out an interactive version of these data: Salinas Valley Lettuce Pest Mapping Tool]. This difference in activity somewhat corresponds to when transplants are grown for local use (spring and early summer) versus desert use (late summer and fall). Transplants that are sent to Yuma are grown when thrips populations and INSV pressure has been historically high – putting them at higher risk of carrying INSV+ thrips.
Species confirmation and virus testing: I collaborated with Daniel Hasegawa (USDA-ARS) for species confirmation and virus testing. Daniel and his team used a genetic testing method called multiplex RT-qPCR to determine if the adult and larval thrips were 1) Western flower thrips (F. occidentalis), 2) Onion thrips (Thrips tabaci), or 3) some other thrips species AND if the thrips were carrying 1) INSV or 2) Tomato spotted wilt virus (TSWV, similar to INSV). For small samples (five or fewer thrips), Daniel's team tested each thrips individually. For samples with more than five thrips, they tested half of the thrips as a pooled sample. If this sub-sample tested positive for INSV, a subset of the remaining thrips were tested individually.
Results: From March through May, we only collected 52 thrips, 50 of which were identified as western flower thrips and none which tested positive for INSV or TSWV. In June, collection shot up almost 10-fold and doubled again in July, somewhat tracking the thrips population increase in the valley (Figure 4). In June and July, thrips densities were consistently higher on brassica transplants compared to lettuce transplants (Figure 5).
Despite collecting over 2,000 individual thrips (1,333 adults and 782 larvae), only two samples, or 1.64% of the tested thrips, tested positive for INSV. The two samples which has positive hits for INSV were collected in June, one off or organic broccoli and one off of conventional cauliflower. None of the thrips collected off of lettuce transplants tested positive for INSV.
Preliminary Conclusions: For the Salinas Valley, the thrips populations on transplants appear to mirror the thrips population in the valley. This is perhaps not too surprising since most transplants are grown on uncovered benches near crop fields. Despite lettuce being a better host for Western flowerthrips (Joseph & Koike, 2021), we consistently collected morethrips frombrassica transplants. We attribute this difference to management practices (e.g., insecticide applications on lettuce transplants) and because brassica transplants tend to stay at nurseries for an additional week.
With this in mind, we may expect that transplanted lettuce fields in the Salinas Valley are more likely to be infected by INSV+ thrips coming in from nearby areas (the prior crop, nearby fields, or weedy areas) rather than thrips from transplant nurseries. Although I would expect to find more INSV+ thrips on vegetable transplants in a year with higher INSV incidence (2023 incidence was considerably lower than prior years), the risk of INSV+ thrips coming in from other sources would increase as well.
For the desert, however, the background risk of INSV is much lower because INSV levels drop off over the summer. In this context, even a handful of INSV+ thrips on transplants pose a proportionally greater risk than in the Salinas Valley. Recognizing this risk to growing regions beyond the Salinas Valley, it is important to continue monitoring INSV levels in transplant nurseries and to work with nurseries to minimize the risk of transporting INSV+ thrips.
References:
- Palumbo, JC, 2022. Thrips and INSV Management in Desert Lettuce. University of Arizona VegIPM Update, Vol 13, No 22, Nov 2, 2022. https://acis.cals.arizona.edu/docs/default-source/agricultural-ipm-documents/vegetable-ipm-updates/2022/thrips-and-insv-management-in-desert-lettuce.pdf?sfvrsn=3088b8b9_2
- Joseph, SV, Koike, ST, 2021. Could Broccoli and Cauliflower Influence the Dispersal Dynamics of Western Flower Thrips (Thysanoptera: Thripidae) to Lettuce in the Salinas Valley of California? Environmental Entomology 50, 995–1005. https://doi.org/10.1093/ee/nvab050
Thanks to Daniel Hasegawa and the entire Hasegawa lab (USDA-ARS, Salinas); John Palumbo (University of Arizona); Kevin Costa, Thomas Costa, and Manuel Aguirre (Headstart Nursery); Francisco Castaneda and Omar Saenz (Growers Transplanting); Lupe Guillen, Maria Alfaro, Alejandro Palma-Carias, and Jim Wilkinson (Dole Fresh Vegetables); Jasmine Rodriguez; Luis Ramirez-Espinoza (CSU-MB); and the California Leafy Greens Research Board.
/table>/span>- Author: Kirsten Ann Pearsons
- Author: Yu-Chen Wang
The 2023 Salinas Fall Pest Management Meeting will be held on the afternoon of Tuesday December 5th, 2023
(postponed from the original date of Nov 2)
Pre-registration is encouraged but not required:
https://surveys.ucanr.edu/survey.cfm?surveynumber=41558
Se recomienda inscripción de antemano:
https://surveys.ucanr.edu/survey.cfm?surveynumber=41560
Traducción simultánea al Español