- Author: Michael Hsu
Detection of fungus causing red leaf blotch spurs call for grower vigilance
Symptoms of red leaf blotch (RLB), a plant disease caused by the fungus Polystigma amygdalinum, have been observed for the first time in California across the Northern San Joaquin Valley.
Molecular DNA testing by the laboratory of Florent Trouillas, University of California Cooperative Extension fruit and nut crop pathology specialist, has confirmed the detection of P. amygdalinum. Formal pest confirmation by the California Department of Food and Agriculture is pending.
The disease, named for the characteristic orange-to-dark red blotches that appear on infected leaves, is typically nonlethal for trees but has been a long-standing problem for almond-growing regions across the Mediterranean. Causing trees to lose their leaves prematurely, the fungal pathogen can significantly diminish crop yields in the current year and the next.
“It is one of the most severe diseases of almonds for Spain and the Middle East,” said Trouillas, who co-authored an explanatory article on the UCCE San Joaquin Valley Trees and Vines blog.
With symptomatic trees seen in multiple orchards across Madera, Merced, San Joaquin and Stanislaus counties, Trouillas said RLB is already “somewhat widespread.”
“From the first observations so far, it seems like it affects some of the most-planted cultivars, like Nonpareil and Monterey,” he added. “We've observed it in a diversity of cultivars already.”
UC Cooperative Extension specialist urges taking preventive measures
According to Trouillas, RLB caused by P. amygdalinum is “highly specific” to almond trees, and generally only affects their leaves. Infection typically happens at petal fall, when small leaflets are first emerging and most susceptible to disease. After the pathogen's latent period of about 35 to 40 days, the first symptoms appear – small, pale-yellow spots on both sides of the leaves.
Those blotches become yellow-orange and then reddish-brown in the advanced stages of the disease during June and July. Now, with RLB symptoms becoming more prominent, Trouillas and UC Cooperative Extension advisors across the Central Valley have seen an uptick in calls.
“PCAs [pest control advisers] have been confused because they've never seen anything like this,” said Trouillas, noting that the yellow-orange-red blotches are symptoms unique to RLB and cannot be confused with other known almond diseases.
Applying fungicides after RLB symptoms appear is ineffective, Trouillas said. The best thing growers can do at this point is to report symptomatic trees to researchers so they can track the prevalence and distribution of the disease.
Growers who see signs of this new disease in their orchard should contact their local UC Cooperative Extension farm advisor.
Preventive measures are the best way to manage RLB, Trouillas said. He urges concerned growers to think ahead to next winter/spring and plan for fungicide applications at petal fall and – if rains persist – also at two weeks and five weeks after petal fall. Fortunately, those are the same three key timings for managing other diseases, like shot hole and almond anthracnose.
“Because RLB is something that is introduced and potentially aggressive, it will be important for growers to keep that in mind next year and be on schedule for next year's spraying program,” Trouillas said.
Additional information on RLB can be found at https://www.sjvtandv.com/blog/first-detection-of-red-leaf-blotch-a-new-disease-of-almond-in-california.
/h3>/h3>- Author: Stephen Dampier
Several years back, I found an ad on Craigslist for Peruvian Hot Peppers for sale. So I trotted on over to Concord and bought some Rocoto and Aji Amarillo pepper plants. The Rocoto pepper plants have thrived, and are around five years old at this point. Most of my peppers are grown in buckets. My current favorite bucket is a 7 gallon nursery pot. They are often available for free or for cheap.
Blah blah blah, more to come.
- Author: Stephen Dampier
I grow Hot Hot Hot peppers including:
- Carolina Reapers
- Red Ghost Peppers aka Bhut Jolokia
- Habanero
- Rocoto
- Serrano
I have other peppers I grow but they vary depending on my mood.
Sweating is good. Hot peppers are fantastic for sweating. Therefore I Love Hot Hot Hot Peppers.
- Author: Shane T Feirer
The first day of the 2024 ESRI User Conference was filled with exciting announcements and innovative stories of Conservation and GIS. With around 21,000 attendees in San Diego and an additional people joining virtually, the energy and enthusiasm were palpable.
Plenary
Jack Dangermond and the ESRI team highlighted several new offerings in their plenary session. Notably, they introduced new datasets in the ArcGIS Living Atlas, including a national tile service of parcel boundaries and a feature layer of iNaturalist species observation data. These additions promise to provide users with even more comprehensive and valuable data for their projects.
The Governor of Minnesota, Tim Walz, a former high school Geography teacher, delivered an impassioned plenary speech on the importance of GIS in solving the challenges we face today. He emphasized the critical need for maps, data, and the work that GIS professionals do to address global issues.
New Apps and Features
ESRI also showcased a range of new apps in ArcGIS Online:
- Portfolio App: Designed to help users highlight key maps of interest, making it easier to share important insights with others.
- Web Editor App: This app offers a web-based editing experience similar to editing in ArcGIS Pro, making it more accessible for users to update and manage their data.
- Generative AI in AI Assistants: The inclusion of generative AI enhances the capabilities of spatial analysis, providing users with more intelligent and responsive tools and apps.
Additionally, several new story map templates were introduced, adding more options for users to create compelling narratives with their data.
Looking Ahead
With so many exciting developments on the first day, attendees can look forward to even more innovations and detailed sessions over the next three days. The future of GIS is looking bright, and the tools and features unveiled at this conference are set to drive the industry forward.
Stay tuned for more updates and insights from the 2024 ESRI User Conference in the coming days!
- Author: Kathy Keatley Garvey
(Continued from the July 13th Bug Squad)
Our resident crab spider, family Thomisidae, appears to be an extremely poor hunter. She waits, camouflaged in the lavender patch, as bees buzz around her. They dart away when she lunges at them.
So here I am, a crab spider, as hungry as can be
Does anyone out there feel sorry for me?
"Yes," say the arachnologists. The apiculturists say "no."
Well, I'll just hang out in the lavender and keep lying low.
Hey, looky there! I'm going to fast-track that bee.
Sorry, I am who I am, and I gotta be me.
The next day, success. Or, as they say, it was "a good day for the spider and a bad day for the bee."
It was also a good day for a freeloader fly (family Milichiidae, probably genus Desmometopa). These flies always seem to appear seconds after a spider (or praying mantis) nails its prey. No dinner reservations required.
Other bees mark themselves "safe" from the crab spider. For now.
And life goes on. For the crab spider. For the freeloader flies.