UC IPM Advisor, Pete Goodell, requests your assistance with an alfalfa IPM survey.
How much IPM is being used in alfalfa in California? A new survey tool wants to help answer that question and we need your help.
If you are interested in participating in developing measures of progress in alfalfa IPM, please volunteer to take the on-line survey. This survey will be used to gauge the level of IPM utilized by California alfalfa growers, similar to surveys conducted in almonds and cotton over the years.
Your participation in this survey will support your Extension and research professionals in getting a better picture of alfalfa pest management practices in California and help identify areas where additional IPM information may be useful.
The survey will take about 20 minutes to complete. All answers are completely confidential and will be grouped for analysis purposes. Survey results will be compiled by the Center for Urban Affairs and Community Services at NC State University. If you have questions about the survey, please contact Dr. Jean-Jacques Dubois, at email@example.com.
Thank you for your consideration in responding to this alfalfa IPM survey.
A land manager recently contacted me with questions about overseeding alfalfa. Her alfalfa stand is diminishing but not to the point of giving up on it. Rachael Long, Yolo County farm advisor, Dan Putnam, UC Davis alfalfa specialist, and Mick Canevari, San Joaquin County farm advisor emeritus, presented on this topic at the Alfalfa and Forage Symposium a few years back and wrote up a proceedings paper on this topic. Additionally, there is a production manual which is available through the UC ANR catalog.
The table below names seeding rates for various annual and perennial species that could be overseeded into alfalfa. The rates have a range (e.g. 4-8 lbs/acre). First, consider the field conditions and the alfalfa stand in order to pinpoint a rate in that range. For example, if the alfalfa is sparse, <3-5 plants/ft2, then perhaps aim on the high end of that range.
Table. Seeding dates and rates for crops overseeded into alfalfa for the Sacramento and San Joaquin Valleys. In the Intermountain Region (Northern California) annual grasses are planted February to April; perennial grasses are planted August to September or March to April. (Table courtesy Long, Putnam, and Canevari, 2003)
If two overseeded species are desired (e.g. one grass and one legume), then the seeding rate could be reduced by 25-30% for both species. So, for example, if orchardgrass and red clover are to be planted over a sparse alfalfa field, then instead of planting the high rates of both, 8 and 12 lbs/acre, respectively, the rates could be reduce 25% to 6 and 9 lbs/acre, respectively, when planting both species.
The reason it is not recommended to overseed with more than two species is because some of the species will outcompete others. The ryegrasses (annual and Italian) are very vigorous and could outcompete red clover, for example. Orchardgrass or tall fescue are best paired with red clover. Berseem clover and a ryegrass, however, could work well together because they have similar vigor and growth timing.
Overseeding should take place in the fall, and ground preparation is important. Scratch up the soil with a harrow; then broadcast the seed, and roll it to slightly cover the seed. Keep in mind that with broadcasting equipment, if seed size is different, the heavy seed may settle to the bottom, and it may not result in a uniform planting of both species. Ensure that seed is mixed well before broadcasting, or use a grain drill. If substantial rain isn't on the forecast, it is best to irrigate the newly overseeded crop to ensure a good stand.
With proper considerations, overseeding could extend the life of an alfalfa field by 2-3 years.
The UC Davis Department of Plant Sciences has announced their field day for small grains and alfalfa. The event will take place on Wednesday, May 11, 2016 from 8:15am to 4:15pm. The small grains field day will take place in the morning, and the alfalfa field day will take place in the afternoon. Lunch will be provided, and there is no registration fee.
The field day is located on Hutchison Road, just west of the city of Davis. Take Highway 113 north from Interstate 80, or take Highway 113 south from Woodland. Exit on Hutchison Road, and go west. Take a right at the first roundabout, left at the second roundabout, and the Agronomy Headquarters is about ¼ mile west in a clump of trees and buildings on your left.
A tentative agenda is as follows:
8:15am – Noon: Small Grains Field Day
7:45 Registration (no charge)
8:15 Welcome and Introductions—Mark Lundy, UCCE/UCD Grain Specialist
8:20 Overview of wheat breeding—Jorge Dubcovsky, UCD wheat breeder
8:25 Introducing new California Wheat Commission Executive Director Deanna Fernandez
8:35 Depart for field
8:50 – 10:50 Advances and directions in small grain breeding
8:50 Promising malting barley varieties —Alicia del Blanco, UC Davis
9:05 Durum Wheat Varieties: new genes for grain yield—Alicia del Blanco, UC Davis
9:15 Promising common wheat releases—Oswaldo Chicaiza, UC Davis
9:30 Evaluation of high resistant starch wheat lines—Andre Schönhofen, UC Davis
9:45 QTL for increased number of spikelets— Junli Zhang and Saarah Kuzay, UC Davis
10:00 Discovering genes for drought tolerance—Tyson Howell, UC Davis
10:15 Combining two stripe rust resistance genes in a single locus—Nicolas Cobo, UC Davis
10:30 Mutants for stripe rust resistance—Josh Hegarty, UC Davis
10:45 Travel to forage trial
10:55 – 11:55: Variety testing and agronomic management of small grain crops
10:55 Small grain forage variety evaluation—Cal Qualset & Lynn Gallagher, UC Davis
11:10 Statewide Variety Development and Evaluation – Wheat, Triticale, and Barley Yields, Performance and Pest Resistance—Mark Lundy & Phil Mayo, UC Davis
11:40 Demonstration of in-field N monitoring & quicktests for improved precision of N fertilization—Jessica Schweiger, UC Davis
11:50 Late-planted heirloom varieties at different seeding rates—Margaret Lloyd, UCCE
12:00 NOON – Barbeque Lunch – Many thanks to California Crop Improvement for the Complementary Lunch!
12:35pm - 4:15pm: Alfalfa/Forages Field Day
12:35 Introductions—Dan Putnam, UCCE/UCD Alfalfa Specialist
12:40 Welcome, Department of Plant Sciences—Chris Van Kessel, Chair
12:50 Welcome from the Dean-Changes at UC Davis in Agriculture—Dean Helene Dillard, Dean College of Agriculture and Environmental Sciences, UC Davis.
1:00 Depart for field
1:05 Insect Management and Disappearing Options for Alfalfa—Larry Godfrey, UC Davis and Rachael Long, UCCE
1:20 Measuring Evapotranspiration (ET) in the Field – Ali Montazar, Project Scientist, UC Davis
1:35 Using ET to schedule irrigations – How to—Daniele Zaccharia, Irrigation Specialist, UC Davis.
1:50 Sorghum Field Studies for Grain and Forage Crops—Jeff Dalberg, Kearney Ag. Center, Fresno, CA
2:05 Field Studies with New Weed Management Options—Mick Canevari, UCCE, San Joaquin County
2:25 Kura Clover, an alternative Clover for Pastures—Dan Putnam, UC Davis
2:35 Subsurface Drip Irrigation Studies on Spacing—Dan Putnam, Daniele Zaccaria, UC Davis
2:50 Deficit Irrigation Strategies for Alfalfa—James Radavich, Dan Putnam, Ali Montazar, UC Davis
3:05 Controlling Gophers in Alfalfa Fields—Roger Baldwin, UC Davis
3:20 Understanding the Fertilizer Needs of Alfalfa—Steve Orloff, UCCE Farm Advisor, Siskiyou County
3:35 Variety Performance Data for Managing Diseases, Insects, and Nematodes, UC Davis—Dan Putnam, UC Davis
3:50 Breeding Alfalfa for California—Scott Newell, Gitanshu Munjal, Charlie Brummer, UC Davis
4:15 Return to Base
Nematodes are microscopic roundworms that use their stylet, or needle-like mouthpart, to puncture plant cells and suck out their contents. The alfalfa stem nematode lives and feeds in the stems and crown of the plant. Symptoms of infection include plant stunting, shortened internodes, and swollen buds (Figure 1), and white flagging where stems lack chlorophyll (Figure 2). Identification of stem nematode can be done under a dissecting microscope by cutting pieces of stems and the crown in a petri dish with water. I took this picture using my smartphone through the eyepiece of the microscope (Figure 3). The stem nematodes are indicated with the blue arrow; they are the almost-translucent wiggly lines emerging from the piece of stem.
Stem nematodes can be a perennial problem in California alfalfa. (See a previous article on the UC Alfalfa and Forage News blog.) They are a particular problem in the spring when the weather is cooler. As temperatures warm, the nematodes recede to the soil and go dormant until cool weather returns. They can cause complete plant die-back, leaving open areas in the field where weeds can become a problem. Unfortunately, management of this pest is challenging. Varieties have varying levels of resistance, but even with a highly-resistant variety, it can be typical to have susceptible plants next to healthy plants within a stand. For this reason, in an area where stem nematodes are a problem, a grower should plant nothing less than a highly-resistant variety. It is important to plant clean seed. Using proper sanitation methods is also advised and would include not moving equipment and wastewater from infected to clean fields, and also not applying manure from cattle fed with infected stem nematode hay to clean fields. Stem nematodes have a limited host range, so rotating out of alfalfa for at least 2 years can help to reduce the problem, but longer rotations (4 years) might be advised under severe infestations. Rotation crops could include small grains, corn, or dry beans. There are no registered nematicides for stem nematode.
In late August, I was requested by a crop consultant to visit an alfalfa field in the Delta that was exhibiting symptoms like those in the picture. The leaves had little white spots near the margins, and generally, the plants had not grown well after the previous cutting. These symptoms are characteristic of potassium (K) deficiency. Delta soils are often deficient in K, so the consultant was going to follow-up with a soil nutrient test.
Fall is the season in which to address alfalfa fertilizer needs. Two nutrients that alfalfa frequently needs are phosphorus (P) and K. [Nitrogen fertilizer (N) is seldom required or profitable in alfalfa because root nodules contain N-fixing Rhizobium bacteria.] P and K should be applied between October and February because it could take 60-90 days for the crop to fully respond to fertilizer application.
A deep-rooted crop, alfalfa can scavenge nutrients from where other crops cannot, but because it has a long growing season, alfalfa has a long season of nutrient demand. Additionally, each cutting removes large amounts of nutrients with the plant tissue. Therefore, proper nutrition is important in maintaining alfalfa yield and quality year after year.
P – important for seedling vigor, root development, and early season growth – is the most commonly deficient nutrient because it can get tied up by the soil. P deficiency may be difficult to diagnose because it can be mistaken for moisture stress, but in general, plants are stunted and have smaller leaves. K is often required because large amounts of it are removed with each cutting. Additionally, sandy soils and/or soils with a long history of alfalfa production can be low in K.
Soil sampling is a reliable way to assess P and K deficiency, but tissue sampling is another way to test for deficiency. P is deficient when soil levels are 4-P (when plant samples are taken at 1/10 bloom). K is deficient when soil levels are 1/10 bloom).
Use a granule (0-45-0, 11-52-0) or liquid (10-34-0) fertilizer to correct P deficiency. These sources are the most economical. If soil or plant tissue tests show deficient levels, then apply P at a rate of 120-180 lbs P2O5/acre (if yield was around 8 tons/acre) and at a rate of 180-270 lbs P2O5/acre (if yield was around 12 tons/acre). Use muriate of potash (0-0-52) to correct K deficiency, or use potassium sulfate (0-0-52, 18% sulfur) if sulfur was also deficient. Correct K deficiency by applying it at a rate of 300-400 lbs K2O/acre (if yield was around 8 tons/acre) and at a rate of 400-600 lbs K2O/acre (if yield was around 12 tons/acre). Single applications of P should not exceed 100-150 lbs P2O5, and single applications of K should not exceed 200-300 lbs K2O. If soil or tissue tests indicate that higher rates are needed, then apply half of what is needed in late fall/early winter and the other half after the second or third cutting. Both P and K are effectively taken up by plants whether pre-plant incorporated or surface applied in established stands. Use these rates to guide your fertilizer applications – remembering that soil type, climate, and yield will influence fertilizer needs – and keep good records of all laboratory results, fertilizer applications, and crop observations. These records will be helpful in developing a long-term, economical fertilization program.
Additional information on how to soil and tissue sample, as well as tables to guide adequate nutrition, are available from this handout.