A California Ag TODAY Exclusive
|Attendees on the Kearney Trams during a Field Tour.|
UC Researchers Fill the Gaps on Many
By Patrick Cavanaugh, Editor
Nearly 100 alfalfa and other
forage growers and pest control advisors gathered TODAY at the Kearney Research and
Extension Center in Parlier, Calif.
UC Cooperative Extension Agronomy Farm Advisor, Fresno County, spoke about the
importance of alfalfa variety selection as a tool for managing pests and
|Shannon Mueller, Ph.D.|
regions where alfalfa is produced determine which pests are most important
for resistance varieties. “Alfalfa varieties consist of a population of plants
which have varying degrees of resistance to an insect or disease. Since alfalfa
fields can sustain considerable loss of individual plants without reducing
productivity, alfalfa varieties with 51 percent or more plant resistance in the
field are considered to be highly resistant (HR), as resistant plants will
make up for losses from other plants.
Alfalfa is heterozygous and
no plant population would have the same resistance strength.
She noted that growers should
know the pest and disease pressure in their areas and buy seed that has the
resistance quality needed.
|Dan Putnam, Ph.D.|
And since alfalfa is a
nitrogen-fixating crop producing between 250 and nearly 1000 pounds of N per
acre, it could serve as a rotation crop, with wheat for example. “The actual
amount depends upon yield and protein concentration. Although most of this N is
removed in the crop, some portion remains to benefit the succeeding crop,” said Dan Putnam, UC Davis Agronomy Extension
“We want to determine the
impacts of rotation with alfalfa on the N fertilization needs of a following crop, such as
wheat. We would like to develop an N credit recommendation for management of N
fertilizers in non-legumes, rotated with alfalfa. He will have data from his
experiment in 2014.
Putnam also discussed UC
sorghum nitrogen and variety studies. “Sorghum has been proposed as an
alternative forage, primarily as a summer annual silage crop for dairy or other
livestock production,” Putnam said. “The primary value of sorghum in the Central San Joaquin Valley, under irrigation, is that it is likely to use less
moisture and N than corn, which is currently a major forage crop in California.”
He reported on N-sorghum
trials from 2011 and 2012, conducted in three locations. The trials are being
repeated this year.
He noted the major advantages of sorghum include:
· Less expensive to establish
· Lower N requirement/lower inputs
· Lower water requirement/ drought resistance
· Lodging issues in some varieties
· Forage Quality (seed percentage/variety specific)
· Yield (variety dependent/ compared with seed costs)
Following Putnam was a
discussion on how to detect if Roundup Ready (RR) alfalfa is present in a
sample. “There are concerns among
growers, marketers, and the general public about the co-existence of RR and
conventional alfalfa,” said Michelle
Leinfelder-Miles, UC Farm Advisor, San Joaquin County. “Key among the
concerns is the possibility for the RR trait to transfer by pollen to
|Michelle Leinfelder-Miles, Ph.D.|
Gene flow has been measured
between alfalfa fields grown for seed production; however, gene flow between
fields grown for hay is largely prevented by management barriers. The
primary barrier is that hay is generally cut before 10 percent flowering so
seed is rarely allowed to form, let alone mature.
However, it is courteous and
wise to employ practices that allow the co-existence of RR and convention
alfalfa. Several important considerations include:
· Growing certified seed.
· Understanding the potential for gene flow. Cross-pollination
is required in seed production but not in forage production.
· Preventing the mixing of hay lots or carry-over bales
· Being aware of neighboring non-genetically engineered
“Testing for GE Traits is a
good way to insure that they do or do not
exist when a customer is sensitive to GE crops,” Leinfelder-Miles said.
Specific test strips are available to easily and quickly determine if an alfalfa
sample is RR. Contact Leinfelder-Miles for more information on testing supplies.
|Jeff Dahlberg, Ph.D.|
There was also a discussion
on Sorghum Variety Trials, presented by
Jeff Dahlberg, Director, Kearney Agricultural Research and Extension
Center. Sorghum, both grain and forage, is a an important feedstuff for
livestock, as well as a fuel stock.
Dahlberg is working on a major
trial with many different sorghum varieties. He is measuring how all of them
stack up regarding fall dormancy, winter survival, all major pests and
diseases, salt tolerance and continuous grazing tolerances. He mentioned many very
good varieties for California Production.
Nearly all forage sorghum
growers are interested in trying to grow crops with less water, and Bob Hutmacher, UC Davis, Department of Plant Sciences, Shafter Research
and Extension Center, presented research that shows respectable yields with
three to four fewer inches of water.
|Bob Hutmacher, Ph.D.|
He stated that he and colleagues
are working on different irrigation timings as well as different amounts of
water on distinct forage and grain sorghum varieties in several locations. “We
are testing forage types and grain types, but all were cut for silage in the
trials,” Hutmacher said. “We are seeing some results that even with lower yields
due to decreased water, there still can be a profitable yield.” He noted
that the yield differences were less on the grain sorghum than on the forage
UC Cooperative Extension Agronomy Farm Advisor, Tulare County spoke about the N
needs of wheat.
“You need to fertilize
according to yield potential,” Wright said. “Some varieties will yield five
tons per acre, and they will require about 300 pounds on N per acre.
“Growers need to develop
variety/nitrogen management strategy what would assure maximum yield and
acceptable protein for all growing areas,” Wright said. “Recent research
indicates that applying N at plating, tillering, boot, and flowering on newer
varieties may increase yield and protein, however more research is needed,” he
|Larry Godfrey, Ph.D|
Wright noted that a good rule
of thumb is three to five pounds N per 100 pounds yield. “However ground water
contamination is an important consideration regarding N-use. But I think
growers can manage their N so that it will not cause any further problems,”
Following Wright was a
discussion on the Blue Alfalfa Aphid that caused enormous problems for growers
throughout the state this year. The
pest populations were very high, the usual materials were not working, and so there were yield reductions. Heading up the discussion
was Larry Godfrey, a UC Davis Extension
Godfrey described the biology
of the Blue Alfalfa Aphid and said there are several generations per year.
He said the pest injects a toxin into the plant while feeding, which causes
much more damage than the Pea Aphid.
Tim Hays, a
PCA with Wilbur-Ellis, Shafter Branch, reported the Blue Alfalfa Aphid was a
big problem in the 1970s, and it has always been at least a minor problem each
year. “This year we had very high aphid numbers; we sprayed but did not get
control. We had good materials that worked well on the aphid until this
season. Clearly this is a resistance issue and the answer we need is new
materials,” Hays said.
Godfrey noted that there is
no apparent evidence that the failure this year was caused by insecticide
resistance, and this did not appear to be a failure of the
A Section 18 was filed for the use of another effective material for the 2014 season. Godfrey noted
that the Section 18 might be canceled soon because a particular registrant has
a new product and the company anticipates it will be registered in 2014 for use in the alfalfa
And finally, Kurt Hembree UC Cooperative Extension
Weed Management Farm Advisor, Fresno County, spoke about weed management in
alfalfa with and without Roundup, on Roundup Ready stands.
He noted that growers need to
plan their program strategy around the weeds that they have or expect, and
dedicate extra efforts to control as many weeds as possible during early stand
“When using glyphosate in
seedling fields, treat the first time at the third trifoliate leaf stage,”
Hembree explained. “Earlier or later timings can result in more weeds escaping
control. And growers must expect some crop injury if tank-mixing with other
Hembree noted that it’s
important to preserve the effectiveness of glyphosate. “Growers need to control
escapes and rotate and/or tank-mix other materials as often as necessary,” he
He noted that a survey
indicates that a large majority of growers are pleased with the Roundup Ready
technology in alfalfa because it provides better weed control with simplicity.
“However, more than half the growers surveyed are not concerned with
glyphosate-tolerant or glyphosate-resistant weeds in alfalfa. The growers who
think this way are in trouble,” said Hembree. He stressed: “If you want these
products to be around, then you must make smart decisions.”
Labels: Alfalfa and Forage Meeting, Bob Hutmacher, Dan Putnam, Jeff Dahlberg, Kearney Round Ready Alfalfa, Kurt Hembree, Larry Godfrey, Michelle Leinfelder-Miles, Shannon Mueller, Tim Hays