Author: Paul Spraycar, The Nature Conservancy
- BirdReturns is a new program from the Nature Conservancy (TNC), organized in cooperation with the California Rice Commission
- BirdReturns compensates growers to provide shorebird habitat – manage your straw and maintain at least 2” of water for 2-8 weeks in fall 2014 or spring 2015
- To apply, farmers submit a competitive bid – name your price
- Deadline to apply: August 1st
The hot, long days of summer have arrived, and that means rice growers are tending their crop, preparing for harvest, and praying for a decent winter. Harvest will be here in no time, but before then growers should consider a shorebird habitat incentive available for fall 2014 and spring 2015.
The program – known as BirdReturns – is being offered by TNC in cooperation with the California Rice Commission. BirdReturns compensates growers to perform straw management and water management of their rice fields. These field conditions, provided at the right times of year, provide critical benefits to shorebirds traveling the Pacific Flyway. The implementation of the program will be as follows:
The pilot BirdReturns program, which took place in February-March 2014, included 10,000 acres of rice fields and several dozen growers. The strong interest and participation demonstrated the significant value of bird-friendly management practices on rice fields. By comparing the participating fields with a collection of other ‘control' fields throughout the valley, TNC scientists were able to determine the value of the participating growers' efforts. Here are the results:
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- Author: Randall Mutters
The milestone signaling the beginning of the reproductive stage is panicle initiation (PI). At this moment, the cells at the shoot apex, which is just above soil, start transforming into the panicle; however, this “primordial” panicle is not visible yet. All that can be noticed is a light green band at the upper-most internode referred to as “green ring” or PI. About a week later, when the panicle grows to 1/16th of an inch long and is visible with the naked eye, rice is at the panicle differentiation (PD) stage. It is very important to correctly identify when plants reach PI and PD since midseason N should be made at or just prior to this growth interval. The internode elongation that is often used as an indicator actually occurs after PI. Calrose varieties do not respond in terms of yield gain to N topdressing beyond PI based on UC research. In fact applying additional N later in the season may increase disease severity and ‘blanking', as well as delay maturity.
Midseason N application may not always be necessary. If the soil has a good supply of N throughout the season, maximum yields can be obtained using pre-plant N fertilizers only. However, there are several factors that prevent this from happening, such as extended drain periods, high soil permeability, or a planned management strategy.
Several methods can be used to estimate the N nutritional status of rice plants at midseason: leaf chemical analysis, chlorophyll meter and the leaf color chart. In all cases, leaf samples should be taken at or slightly before PI. The Y-leaf should be used to determine plant N content. The Y-leaf is the most recently fully expanded leaf. It is important to know the stage of growth when sampling for leaf-N because the N content can vary drastically over time. The adequate N range for tissue N at PI is 3.2 – 3.6% (Table 1); concentrations below this range indicate an N deficiency and warrant topdressing.
Table 1. Guide for leaf nitrogen percentages at different stages of growth.
Source: Rice Nutrient Management in California. UC ANR No. 3516.
The chlorophyll meter can be used to estimate N content by measuring the amount of light absorbed by chlorophyll in leaves. The meter must be calibrated against leaf samples analyzed in the laboratory. For cultivar M-205, a meter reading of 32 corresponds to the critical value of 3.3% N. The UC leaf color chart is a very practical, accurate and reliable method to estimate plant N content. It consists on a series of panels with colors that match the color of plants with different N contents (Fig. 1). By comparing the chart with color of the Y-leaves, an estimation of the N status of the rice plant is possible. The chlorophyll meter and the color chart have the advantage of allowing “real time' determination of plant N concentration, whereas the leaf chemical requires a few days for processing. The chlorophyll meter ‘samples' a very small area of the leaf (2 x 3 mm). Therefore a large number of readings are necessary to get a reasonable estimation of leaf N levels.
Figure 1. Leaf Color Chart for evaluating nitrogen status in rice.
Keep in mind that greener is not necessarily better. Studies conducted on M205 and M206 at multiple locations demonstrated that tissue N levels at PI above the critical level do not translate into higher yields (Fig. 2).
Figure 2. Yield as a function of leaf N at panicle initiation. Pooled across varieties (M-206, M-205) and location.
Last year, resistance to the herbicide propanil was confirmed in populations of smallflower umbrella sedge and ricefield bulrush. Considering that propanil is a common “clean up” herbicide, used in almost 400,000 rice acres every year, propanil resistant sedges are a significant threat to the rice industry. To make matters worse, populations of these propanil resistant sedges were also found to be resistant or partially resistant to several ALS-inhibiting herbicides (Londax, Sandea and Granite).
Herbicide trials conducted last year showed sedge populations resistant to propanil and ALS-inhibiting herbicides were susceptible to the herbicide Shark H2O. For control of propanil resistant sedge, Shark H2O herbicide can be applied at one of two timings:
- Early, at the 2 to 4 leaf stage of rice, for control of submerged weeds, at a rate of 7.5 oz/a, or
- Twenty to 45 days after seeding, to the foliage of exposed weeds at a rate of 4 oz/a.
Additionally, the herbicides Bolero and Abolish used at standard rates and timings also control propanil and ALS-resistant smallflower umbrella sedge.
Other herbicides will need to be used to control the whole spectrum of weeds present. For example, programs could include an early application of Shark H2O followed by Regiment or propanil; Cerano or Bolero can be followed by a later application of Shark H2O to control escapes. Remember to read and follow the label.
When dealing with herbicide resistant weed populations, do your best to control all weed escapes and late season flushes. Harvest infested checks last, so your equipment does not spread seeds of resistant weeds to uninfested checks.
Growers who are not experiencing reduced efficacy of propanil should implement these well known strategies to delay the development of propanil resistance:
- Avoid repeated use of herbicides with the same mode of action.
- Use different modes of action in mixtures and sequences.
- Use label rates and avoid low rates.
If you suspect propanil resistance, collect mature sedge seeds in problem fields and bring them to the Rice Experiment Station, where they will be tested during the winter. Control failures are not necessarily due to resistance, but can be caused by application problems such as incorrect timing, dosification errors, mixture incompatibilities, etc.
Smallflower umbrella sedge in rice field
The 2014 rice season is in full swing. Some ground is still being worked, and fields are being flooded and planted. Calls are starting to trickle in (algae, tadpole shrimp) and it's looking like it will be a challenging season.
But in this blog entry I'm not going to write about rice. I want to take this opportunity to tell you about a very special celebration, a centennial celebration.
One hundred years ago, on May 8, an act of Congress formally created the Cooperative Extension system nationwide. This legislation called for “cooperation” between land-grant universities, the USDA and county governments in order to fund an agent to work in the community “extending” the agricultural knowledge generated on university campuses and agricultural experiment stations.
In California, the University of California was in charge of establishing extension agents in the counties throughout the state. Humboldt County was the first to get an agent on July 1913, a year before passage of the federal legislation. The agent had the title “farm adviser”, which was later changed to “farm advisor”.
Today, UC Cooperative Extension advisors are present in all California counties, and include not only farm advisors, but also natural resources advisors, nutrition, family and consumer sciences advisors, and 4-H youth development advisors, among others.
UC Cooperative Extension has evolved significantly in the last 100 years, but its core mission remains the same: to serve the people of California.
Happy centennial, UCCE!
In early 2012 UCCE conducted a survey of rice storage facilities (on and off-farm) to see what research and extension needs the rice industry had in this area. The results of the suvey have been published in the journal California Agriculture, and if you are interested, the article can be accessed on the web here: http://californiaagriculture.ucanr.edu/landingpage.cfm?article=ca.v068n01p38&fulltext=yes
The survey showed that storage facilities are users of IPM: most operations rely on monitoring, thresholds, sanitation and aeration to manage pest problems.