I got a report from a PCA early in the week of blast infections detected near Maxwell. Blast can occur at any time during the development of the crop. When it infects leaves, it is called leaf blast. If it infects the base node of the panicle, it is called neck blast, if it is on the nodes of tillers, node blast, etc. In all cases, it is the same pathogen. Usually, the first visual indication of blast infection happens in nitrogen overlap areas in the form of dead circular spots.

If you inspect these areas closely, the plants in the center are burned to the water, and the typical diamond shaped lesions can be found in the leaves of surrounding plants.

We do not recommend treating leaf blast. But presence of leaf blast is a good indication that a fungicide treatment will be needed once the crop starts heading.

Blast is a multi-cycle disease, meaning that infections produce spores that then can cause more infections later. After an infection occurs, lesions form after 14 days, and 3 days later new spores are formed. These spores can then repeat the cycle. This is why it is important to protect the panicles if leaf blast is present in a field or surrounding fields. Time your fungicide application anywhere from mid boot to panicle emergence.

All our varieties are susceptible to blast, with the exception of the new M-210. M-206 is considered less susceptible than M-104 and M-205. We have not seen the response of M-105 and M-209 in the field yet, but I suspect they are very susceptible based on their background.

An in-depth workshop that covers the principles and practices of rice production:

Tuesday, August 7, 2018

8:30 – 3:00 pm

Lundberg Family Farms

5311 Midway

Richvale, CA 95974

Program:

• 8:30 Sign in, pick up class materials
• 9:00 Introduction and Workshop Overview         
• 9:10 Rice Growth and Development       
• 9:30 Land Formation, Water Management          
• 9:50 Tillage, Planting and Stand Establishment  
• 10:10 Break
• 10:30 Variety Selection 
• 11:00 Invertebrates
• 11:30 Diseases 
• 12:00 Lunch
• 1:00 Fertility
• 2:00 Weeds       
• 3:00 Adjourn

Enroll online at http://ucanr.edu/rice2018

Prepaid enrollment ($100) is required, and enrollment is limited  to 75 people. Price includes Rice Production Workshop Manual, lunch and snacks. Please enroll by August 1st to ensure your participation. Seats will be filled on a first-come  basis.

DPR and CCA continuing education credits requested.

For more information, contact Luis Espino (530-458-0578), Whitney Brim-DeForest (530-8227515) or Michelle Leinfelder-Miles (209-953-6120), Farm Advisors, UC Cooperative Extension.

I looked at the USDA planting progress for rice in 2018. What the data show is that 50% of the crop was planted by May 14. That is 5 days earlier than last year and a couple days later than average.  The delay was due to significant rains in early and mid-April which delayed groundwork. As I write (in the first full week of June) there are still some fields being planted – though not many.  Having the benefit of driving around the valley for various research projects I am involved with, it seems that the west side of the valley was able to plant much earlier than the east side of the valley. So the east side of the valley may be further behind than the statewide data suggest. Last year, the late planting date was combined with a very warm summer; which, I feel, resulted in lower yields than many growers were used to.  In general, there is a slight yield decline with delays in planting date. However, there are many examples in the data where we have had high statewide yields when 50% of the acreage has been planted by May 15. For example, in 2016 the 50% planting progress date was May 15 and that year was the second highest statewide yield average on record (88.4 sacks/ac). So, on a statewide basis, I think this year is off to a good start, although I do have some concerns about the late planting dates I have been seeing on the east side. I think the outcome in terms of yields will depend on summer temperatures and if we have a favorable fall for a timely harvest.

Tadpole shrimp (TPS) are starting to pop up in rice fields. A grower asked me when is the period when rice is “safe” from TPS. He is seeing very small shrimp, and seedlings are already past the first leave stage of rice (lsr).

To determine if rice is going to escape TPS injury, two things need to be considered, the rice seedling stage and the size of the TPS. It is difficult to determine the size of TPS, but if you pull one out of the water and its shell is smaller than half the size of a medium grain rice seed, then it won't injure a germinating seed. TPS larger than that will readily feed on germinating seeds and seedlings.

TPS with a shell size about half the size of a rice seed feeding on developing root. 

TPS will feed on seedlings until they reach the first leave (when the spike is well developed). TPS don't seem to like feeding on the green tissue. However, they will feed on roots. If the main root is exposed, seedlings are still at risk of TPS injury.

TPS feeding on exposed roots of 1 lsr.

Use this guideline when you scout:

One more thing to considering when scouting. If rice escapes injury and TPS are not treated, they will lay eggs that will stay in the soil and hatch next season.

When it comes to TPS management, fields that can be flooded quickly have an advantage over fields that take several days to flood. A quick flood followed by timely seeding will result in seedlings that can reach the 1 lsr before the TPS grow too large. In fields where flooding takes several days, TPS will have a head start and may reach the injuring size before the seedlings reach the 1 lsr.