- Author: Wendy Powers
It's time, again, to start the weekend yard work routine. I spent a small part of the time this weekend weeding but didn't come close to catching up with all that somehow grew since Thanksgiving. And now, with more rain on the way and next weekend already committed for a trip to DC with our CARET representatives, I imagine the weeds will be far ahead of me by the time I get back to yard work again. That's just how it goes.
I'm reviewing my calendar and weeding out things that just might have to go on hold while I work through the merit and promotion documents (79 total, I hear, with all of them left to review by early June). Also, there are many, many meetings to attend some of which are standing meetings while others are somewhat new to the calendar. I need to decide where things fit in my Focus Funnel. I suspect some of the things I really enjoy (county visits) may slide. I need, also, to determine which activities present themselves as competing commitments and, as a result, deter my efforts to achieve my stated goals for the good of the Division.
If I need some inspiration to stay focused and avoid competing commitments all I need to do is look at this morning's UCOP Daily News Clip. There was a great call out to work in Fresno County. Take a look; the work is inspiring!
I'm looking forward to seeing the County Directors and the REC Directors this week. Both groups are meeting in Davis. The Research and Extension Council meets Tuesday evening, followed by the County Director meeting all day Wednesday. The REC meeting, on Thursday, is an ‘all-hands' meeting so Business Officers and Superintendents will be in attendance. Each of the meeting agendas is quite full. I expect I will learn a lot and later need to weed through all of the information to separate out action items from ideas for future use. It already appears that the weather may make travel challenging for some, but hopefully, travel disruptions are minimal. My week should be hassle-free as far as travels go; just a quick trip to Irvine on Friday. Then I head East again over the weekend, so plenty of opportunities to traverse the airports at that point.
UA-130685520-1
- Author: Steven A. Tjosvold
Plant diseases– their occurrence and severity– result from the impact of three factors: the host plant, the pathogen, and the environmental conditions. This is represented with the disease triangle.
If any one of the three factors is missing, the triangle is not complete, no disease will occur. Simply, plant disease will not occur if there is no viable pathogen, or no susceptible host plant, or the environmental conditions are not favorable. The severity of disease depends on the favorable level of each factor. How susceptible is the plant? How virulent is the pathogen? How conducive are the existing environmental conditions in supporting disease and pathogen spread?
The triangle also helps illustrate that the 3 factors are interacting with each other. The clearest example of this is how the environment factor interacts with the pathogen and host factors. Previous blogs illustrate the importance of leaf wetness on pathogen infection and disease severity. Long durations of free water on a susceptible plant can increase pathogen infection and disease severity. At the same time, the low- sunlight conditions, when these wet periods could occur (e.g. winter), could also be stressful to the plant, and the plant is less likely to mount defensive reactions to fend off infection.
Learn about the biology for any disease you are managing. Consider the disease triangle and the three interacting factors, and how management practices might help weaken or break the triangle's bond. For example, could you grow non-susceptible plant varieties or species? Could you eliminate the pathogen through judicious sanitation practices? Could you manage leaf wetness and relative humidity to create unfavorable environmental conditions for disease?
Could you grow non-susceptible plant varieties or species?
Although these three plant hosts all have rust diseases, each host is infected with a unique plant pathogen that attacks its specific host. In managing these diseases, a strategy of host resistance might be employed, where crops of non-susceptible hosts are rotated into the infested area. Conceivably these three hosts could be rotated.
Could you eliminate the pathogen through judicious sanitation practices?
Sanitation is a key management practice that employs the strategy of eliminating the pathogen from the growing area. Here, sanitizing shoes before entering the greenhouse. Cleaning soil from tools and sanitizing them before use. Properly covering and disposing of rogued plants or cut flowers (not shown here!).
Could you manage leaf wetness and relative humidity to create unfavorable environmental conditions for disease?
AND Then, can you add the 4th factor for Disease? That of TIME. It takes a certain amount of time for a given disease to show up. Some strike rapidly and others are chronic and persistent. Different time frames allow for different urgency for treatment. It's always best to remove one of the three Triangle factors before dealing with the Disease Pyramid which includes Time:
https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=19842
The Disease Quadrangle
https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=28845