For anyone making field decisions in California, timing is everything.

Pest pressure, disease risk, irrigation needs, spray decisions. They all depend on weather patterns and regional activity. Miss the window and you are reacting instead of preventing. Get it right and you protect yield, cut unnecessary input costs, and stay ahead of compliance requirements before they become a problem.

Most experienced agricultural professionals do not rely on a single source. They layer several tools together, weather station data, degree-day models, regional field updates, regulatory alerts, and triangulate between them to build a picture of what is happening and what is coming next.

California has some of the most advanced agricultural monitoring infrastructure in the world. The challenge is not access. It is knowing which sources to trust, what each one is actually built for, and how to use them together without spending your whole morning in browser tabs.

Below are seven of the most trusted sources used by PCAs, farm managers, and growers across California specialty crops including almonds, grapes, citrus, berries, and vegetables.

1. UC IPM: Weather, Models and Degree-Days

Run by: University of California Agriculture and Natural Resources

Link: ipm.ucanr.edu/weather/

This is the core bookmark for pest timing work. If you only set up one of these links, make it this one.

The UC IPM weather and models hub connects three things that field advisors constantly triangulate: local weather data, pest and plant phenology models, and degree-day calculators. Pest development is driven by heat accumulation, not calendar date. Two fields in different microclimates can be weeks apart in pest pressure even if they are geographically close. A degree-day model accounts for that. A calendar does not.

Most PCAs and farm managers use this to time scouting windows and align treatment decisions to the most vulnerable stages of pest development, which in practice means fewer unnecessary sprays and better results when you do spray.

2. CIMIS: California Irrigation Management Information System

Run by: California Department of Water Resources

Link: cimis.water.ca.gov

If you do any irrigation scheduling, CIMIS is probably already on your radar. It is one of the most widely used agricultural weather networks in the state, providing temperature, humidity, wind, solar radiation, and reference evapotranspiration from a network of stations across California.

Worth flagging for pest and disease work: CIMIS is also a solid backbone for degree-day calculations, but only if you are using the right station. Matching your station to your field's actual microclimate matters more than most people realize. A station ten miles away in a different valley floor can give you numbers that are meaningfully off.

If you are pulling data regularly, CIMIS supports automated delivery via email, FTP, and a web API. Most operations set this up once and let it run.

3. UC IPM: Pest Management Guidelines

Run by: UC Statewide Integrated Pest Management Program

Link: ipm.ucanr.edu/agriculture/

Weather data and degree-day models tell you when to look. These guidelines tell you what to look for and what to do about it.

UC IPM publishes crop-specific guidelines covering pest identification, monitoring techniques, economic thresholds, and management strategies, structured as year-round programs broken into seasonal windows: dormancy, bloom, fruit development, harvest, postharvest. For most PCAs this is the reference they have had open in a tab for years. For farm managers and growers newer to IPM, it is the clearest starting point available.

If you work across multiple crops, the structure is consistent enough that you can move between them quickly once you know how they are organized.

4. UC ANR: Pest Management Blogs

Run by: University of California Agriculture and Natural Resources

Link: ipm.ucanr.edu/blogs/

The blog directory is a curated index of region and crop-focused blogs run by UC Cooperative Extension advisors, people who are actually in the field writing about what they are seeing right now. The Almond Doctor, Grape Notes, Salinas Valley Agriculture, Strawberries and Caneberries. These are field notes at scale, not marketing content.

One honest caveat, which UC ANR states directly: these regional summaries are reference material, not a substitute for your own scouting. What is showing up in one district may have nothing to do with what is in your blocks. But for understanding what is moving across the region and what other advisors are watching, this is one of the fastest signals available.

5. CDFA Plant Health: Pest Alerts and Quarantine Maps

Run by: California Department of Food and Agriculture

Link: cdfa.ca.gov/plant/

When a pest situation becomes regulatory, this is the official source. CDFA Plant Health tracks invasive pest detections, publishes quarantine boundaries, maps treatment areas, and issues official alerts statewide.

For anyone moving product, growers, packers, shippers, quarantine updates can affect operations overnight. The site includes dated maps and treatment area postings for major programs including invasive fruit fly projects and the ACP/HLB citrus program. Most major program pages have email alert options worth setting up if any of these programs touch your region or crops.

6. California Citrus Threat

Run by: Citrus Pest and Disease Prevention Program, administered by CDFA

Link: californiacitrusthreat.org

Citrus specific, but if you work in citrus it belongs on your list.

California Citrus Threat consolidates ACP and HLB detection status, quarantine zone maps, and plain-language updates in one place, without requiring you to navigate multiple CDFA regulatory pages to piece together the picture. It also routes suspected detections directly to the CDFA pest hotline.

7. National Weather Service: Frost, Freeze and Weather Alerts

Run by: National Oceanic and Atmospheric Administration

Link: weather.gov

Pest models and crop updates are important. But short-fuse weather events often drive the most urgent farm decisions.

Frost advisories, freeze warnings, heat advisories, high wind alerts. These determine whether you run frost protection, whether a spray application can go ahead, whether crews should be in the field at all. During bloom periods in tree fruit and nuts, or in cold-sensitive berry and vegetable systems, a freeze warning changes your whole day.

Everything else on this list helps you plan ahead. NWS is what you check when the plan needs to change right now.

How these sources work together

Experienced agricultural professionals use these tools as a layered decision stack, not independently.

CIMIS and NWS cover weather reality, what is actually happening in your microclimate and what acute hazards are coming. UC IPM's models hub translates that weather data into pest timing, when emergence windows are opening, when disease pressure is building, when degree-day accumulation puts you in a treatment window. The pest management guidelines then tell you how to act on that signal, what to scout for, which thresholds matter, what the options are.

The UC ANR blogs layer on regional context, what advisors and scouts in similar operations nearby are actually finding. And CDFA Plant Health, along with California Citrus Threat for citrus operations, keeps you connected to the regulatory picture, quarantine boundaries, treatment areas, and movement restrictions that can affect your operation whether you are expecting it or not.

A lot of field advisors and farm managers end up with a Monday morning routine built around some version of this stack. Check CIMIS for the week's weather. Pull UC IPM to see where degree-days are landing. Scan any relevant Extension blogs. Check CDFA if anything has been moving in the region. It takes twenty minutes and it shapes how you prioritize the whole week.

These sources tell you when to look. Tellia helps you capture what you find.

All of that monitoring signal only matters if what you find in the field actually gets recorded.

For most operations, that is still the hard part. Observations scribbled on notepads. Voice memos sitting in a camera roll. Details that made sense in the field and are fuzzy by the time you are at your desk trying to write them up at the end of the day.

Tellia was built around that problem. Call in or leave a voice note from the field and Tellia automatically structures everything into organized records. No forms, no typing, no catching up at night.

These sources tell you what to watch for. Tellia makes sure what you find actually gets recorded.