Back in 2017, I wrote a brief blog about myrtle spurge being present in Lassen County. Myrtle spurge was evaluated by CDFA and determined to warrant being placed on the A list of noxious weeds here in California. Recently, a local landowner asked me where he could find a list of noxious weeds within the state. This landowner was specifically interested in myrtle spurge, but wanted to know what other species he should be on the lookout for.

Since moving to California, when folks have asked me about noxious weeds I have sent them straight to the source. The CDFA encycloweedia page which lists all of the noxious weed species in the state. When you click on each species, it will bring you to a detailed description of that species, biology, history, pest rating and even various control methods. It is a one stop shop for noxious weed information!

However, when I looked for myrtle spurge on the web page, I couldn't find it…. I thought there had to be a mistake! Upon further investigation by scrolling down to the bottom of the page, I realized that the webpage hadn't been updated since July 15, 2016, well before myrtle spurge was officially listed as a rated pest. It brought me back to school, where teachers always hounded us to pay attention to website dates!

Picture one: Myrtle spurge growing among rocks

But, if all of the updated noxious weeds were not listed on encycloweedia, where were they listed?

With a little bit of digging, I was able to find a webpage with pest rating proposals and final ratings specific to  weeds in California. On this page, there were an additional 67 weed species with pest ratings listed. Comparing the original list and this new list, there was an overlap of 25 species which had their rankings re-evaluated and occurred on both lists. Forty two species were only listed on the pest rating proposals and final ratings web page, but not the encycloweedia webpage. This included A ranked species, like myrtle spurge and prickly acacia, as well as C ranked species, like cheatgrass and Sahara mustard. Seven of the 42 species were listed on the D list, which indicates there is no mandated state action needed. Another place I often check for noxious weed ratings is the federal USDA plants database. They have a webpage for each state, listing the noxious weeds species. Out of curiosity, I gave it a gander and only found two of the 35 newly listed species represented on the federal webpage (false pickerel weed and jeweled distaff thistle).

I was confused. Were species listed on the pest rating proposal web page actually noxious weeds, or just proposed noxious weeds? So, I called the CDFA to figure it out! What I found out is that these species have not officially been added to the 4500 noxious weed list, but they are going to be added in the near future. I also found out that even though they are not on the 4500 list, they are still considered rated pests by the state, and should be treated as such!

Noxious weeds are legally required to be controlled/managed under state law, and there are two places to look for species that you need to watch out for. There are 198 noxious weeds listed on encycloweedia, and an additional 35 species listed on the pest rating proposals and final ratings web page. When looking for noxious weeds to manage in California, make sure to check both web pages, not just one. Knowing what weeds are listed is the first step to identifying them in the field and preventing their spread!

The table below lists species named on the newer pest rating proposals webpage but not encycloweedia.

Table One