Angular leaf spot (or as some insiders refer to it, "ALS") caused by the bacterial pathogen Xanthomonas fragariae, has been showing up a bit more than expected this year in several strawberry varieties, including Cabrillo and Petaluma.
I'd like to demonstrate several descriptions of this disease from the UC IPM guidelines for strawberry with pictures just taken this morning on a field of Cabrillo variety strawberry. Picture 1 shows the water soaked spots on the leaves which as a matter of fact when seen in the low angle of light in the early morning show the angular formation of infection bounded by the venation of the leaf. Further, picture 2 shows the viscous exudates (reminiscent of pus) matched to these areas on the underside of the leaf. These exudates tend to be moist and lustrous in the morning, and dry down to a more scaly appearance as the day progresses.
These exudates come from the breakdown of the plant cell walls that this pathogen engenders, and the exudates are of course also filled with Xanthomonas bacteria cells. Given the size and proliferation of these disease propagule filled exudates, it doesn't take much imagination to realize how easily it is to move disease around, especially via rain and overhead irrigation.
The Guidelines state that cool, moist days (think rain) followed by cold nights near freezing are what favor this disease, so hopefully by now we are through most of the woods on this issue for this year.
Enough is enough on lygus. Your colleagues Shimat Joseph, Pete Goodell and Mark Bolda, along with some serious assistance from the UC ANR support unit have assembled the best and brightest minds in the world on lygus and other heteropteran pests right here at your door this coming April.
If I were a grower or PCA serious about managing lygus and other plant bug pests, I wouldn't miss this event for the world, especially the third day which is oriented towards real world applications.
UC ANR Cooperative Extension will be offering a multi-topic Heteroptera insect group Symposium on April 18-19, 2017, followed by a Heteroptera Workshop and local tour on April 20. Following the International Lygus Symposia held in Ottawa Canada, Monterey CA, and Scottsdale AZ, the program will provide participants with the latest information and research from international experts on Lygus, Plant and Stinkbugs. Informational sessions, including keynote presentations from Dr. Tracy C Leskey, Director USDA Agricultural Research Service, and Dr. Kim Helmer, Research Entomologist USDA Agricultural Research Service, will cover topics such as biology and ecology of the group, management of pest species, advances in chemical ecology, and focused crop seminars.
The program will take place at the Embassy Suites Monterey Bay-Seaside at 1441 Canyon Del Rey in Seaside. Registration is currently open and offered at a three-day combination package or a single-day workshop option. Discounted early registration ends April 1, 2017. Register at http://ucanr.edu/sites/2017bugsymposium/Registration/.
Visit our website to see the latest information and to sign up to receive email notices. http://ucanr.edu/sites/2017bugsymposium/.
If you have any questions, please contact Kellie 530-750-1259 firstname.lastname@example.org
UCCE Farm Advisor Mark Bolda will be providing a training on light brown apple moth (LBAM) that qualifies attendees to be an “approved scout” relating to the Compliance Agreement for shipment of berries to Canada. On completion of the brief training, attendees will receive a Certificate as a record of their participation.
This training will be held once in English and once in Spanish.
Where: UCCE Auditorium, 1430 Freedom Boulevard, Suite E, Watsonville, CA
When: April 24 – 8:00-9:00 AM in English
April 25 – 8:00-9:00 AM in Spanish
No pre-registration necessary. All are welcome to attend, even if they do not intend to ship berries to Canada.
No continuing education hours will be offered at this meeting.
Please call Mark at (831) 763 8025 if you have any questions.
Nice, very short article - doesn't take more than 5 minutes to read - addressing the general question of soil acidity and nutrient availability for plants. As many of you know, I am a big fan of soil acidity for plant culture but as the article clarifies, acidity is only beneficial down to a point, below which the availability of N, P, Ca, Mg and K drops off too much apparently.
Key here is that favorable pH for plants is in a RANGE from 5.9 to 7.0. Still, if you peruse the included graph closely you get the strong sense that optimum availability of most nutrients is at 5.9, especially the micronutrients iron, copper, manganese and zinc.
Many of our soils for berries in Salinas and Watsonville range from 6.5 to 7.5, so there are many above optimum (for many reasons, I know that). It would be an interesting avenue of research to pursue a soil that is at 5.9 and see how well a crop of berries does there.
UCCE, and the Strawberry Commission with the generous sponsorship of the BASF Corporation are putting on a short preseason workshop on how to get the most out of managing mites in strawberry.