Do you want to make sure your freshly planted rice fields don't look like the muddied mess on the left below (vs. clear on right) following a pyrethroid application? Wondering if your tadpole shrimp are becoming less susceptible to pyrethroids? We do too! Pyrethroids are widely used for managing resistance, and resistance seems to be a growing issue.

We are looking for additional fields where we can sample tadpole shrimp to test for pyrethroid resistance. We will be gathering soil/shrimp and then using these samples to run laboratory bioassays and measure susceptibility. The goal is to start measuring precisely how susceptible populations are in different fields. This will...

The last time we saw a severe blast epidemic was 2011. Since then, we haven't had much blast; in fact, I had not see any blast at all during several years. I don't think 2019 qualifies as a severe blast year, but there is more blast than in the previous few years. 

Blast is caused by a fungal pathogen, Pyricularia oryzae. This fungus can affect any plant part, and usually we refer to blast according to the tissue affected. Leaf blast, node blast, collar blast, and neck blast (when it affects the node right below the panicle) are all caused by the same pathogen. 

N management in wet year: revised based on cool weather.

Earlier this week I sent out a blog discussing N management during a wet year. In the blog, one scenario (Scenario 2) mentioned was “I decided not to apply aqua but just go ahead and flood field when the rains started”. I was traveling around the valley yesterday looking at fields and I saw that rice that had been planted was not coming up – or was coming up very slowly. These rains have been accompanied by very cool weather (almost 10 degrees cooler than normal for this time of year) and the 10 day forecast shows continuing cooler than normal weather. This means plant growth and N uptake is going to be...

Rain in May, especially in the amounts we have seen this year are far from ideal for rice growers. It makes establishing seedling, N management and weed control extra challenging. Rain in May is not new. In 1995, 1996, 1998, 2005 average May rainfall in the Sacramento Valley was 2.3 inches and average statewide yields of those years was 73 sacks/ac. Interestingly, in 2011 the Sacramento Valley also received about 2” in May, but yields were 83.5 sacks. Statewide yields over the last 10 years have averaged about 85 sacks/ac.

Here I want to address some nitrogen management concerns. I address three potential scenarios below and some ideas on how to best manage N fertilizer.

Scenario 1. I applied aqua-N before...