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~J~fUNIVERSITY of
IFAS Exten-sion
Agronomy Notes
Volume 34:02 February 2010
Features...
Forage
Cover Crops, Winter Grazing and Nutrient
A vaila bility........................................................... Pag e 2
Impacts of Grazing Small Grain on Following Cotton
C rop ...................... ............ ... ........................ .. Page 3
The 'ABCs' of Good Forage Establishment............. Page 3
Weed Control
Mile-a-Minute: A New Weed in South Florida...........Page 4
IFAS CEU Day ..................................................... Page 5
Miscellaneous
C alendar............................................................. Page 2
Affirmative Action Employer authorized to provide research, educational information and other
services only to individuals and institutions that function without regard to race, color, sex, age,
handicap or national origin. For information on obtaining other extension publications, contact your
county Cooperative Extension Office. Florida Cooperative Extension Service/Institute of Food and
Agricultural Sciences/University of Florida/Millie Ferrer-Chancy, Interim Dean.
"Agronomy Notes" is prepared by: Maria Gallo, Interim Chair and Y. Newman, Extension Forage Specialist
(ycnew@ufl.edu); G. Anguelov (ganguelov@ufl.edu); J. Ferrell, Weed Specialist Oferrell@ufl.edu); F. Fishel,
Pesticide Information Officer (weeddr@ufl.edu); K. Langeland, Aquatic Weed Specialist (gator8@ufl.edu); J.
Marois, Extension Agronomist (jmarois@ufl.edu); B. Sellers, Extension Weed Specialist (sellersb@ufl.edu); and D.
Wright, Extension Agronomist (wright@ufl.edu). Designed by Cynthia Hight (chight@ufl.edu.) The use of trade
names does not constitute a guarantee or warrant of products named and does not signify approval to the exclusion
of similar products.
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We recommend cover crops prior to row crop production
.- to protect soil from wind and water erosion, to store
, nutrients in the plants for later release for following crops
and to ultimately increase yields or quality of following
crops. Cattle can also have an impact on the amount of N,
P, K, Ca, and Mg that is available to the following crop.
The figure below shows the amount of nitrate N available
in the soil down to almost a meter deep. Even though both
areas had an oat and rye cover, cattle were recycling the
-> above mentioned nutrients and from 2-4 times the amount
of nitrates were available in the top 20 cm as from non-
grazed areas that had the same amount of fertilizer applied.
Likewise, irrigation will often leach nutrients through the
soil profile and if more water is applied than the soil can
absorb, it will move through the profile taking nutrients
with it. Nitrates move with the soil solution and the
irrigated non-grazed plots had a nitrate surge at 100 cm or
lower out of the normal root zone of most agronomic crops
meaning that it will ultimately end up in ground water.
Therefore, livestock do aid in keeping nutrients in the
upper root zone of the soil to be available for following
crops.
Submitted by Extension Agronomists, North Florida REC, Quincy:
Dr. David Wright, dwright@ufl.edu;
Dr. James Marois, jmarois@ufl.edu;
Dr. Gueoraui Anauelov. sansuelov(Zufl.edu
To follow the link, press "Ctrl" and put cursor over link, and "click. "
Feb. 4-15
Feb. 7-8
Feb. 17
Feb. 24-26, 2010
May 3-6
May 5-7
July 12-16
Aug. 1-5
Florida State Fair, Tampa
American Society of Agronomy Southern Branch, Orlando
Strawberry Field Day, Gulf Coast REC, Noon 5pm, Wimauma
UF Water Institute Symposium, Gainesville
Aquatic Weed Control Short Course, Coral Springs
Florida Beef Cattle Short Course, UF Gainesville, Hilton UF
Greater Everglades Ecosystem Restoration Meeting, Naples
Ecosytem Restoration Conference (NCER), Baltimore, MD
Agronomy Notes Page 2
i
4J40
41
a
Cotton Yield Response to Irrigation and
Grazing (2008 Marianna)
In bahia rotation
1787
-
1712
Irr Non-irr Irr Non-irr
Grazed Non Grazed
With higher nitrate N in the soil where cattle graze small grain, we
found that nitrates were higher in the cotton plant throughout the
season and were higher than recommended in the vegetative stage
indicating that the residual and applied N may have been too high
with a potential for leaching. However, cotton yields were higher
in 2008 where cattle had grazed small grain as compared to
similarly treated plots that were not grazed as noted in the figure
below. We need additional years of research to determine how
much commercial N can be reduced on cotton where cattle have
been grazed. This would be dependent on cattle number and size,
soil type, soil moisture, how much N had been applied to small
grain and other factors. Nitrogen can be reduced with recycling
and probably by a third to one half without yield loss. Having a
legume in the winter grazing could reduce that even further.
Submitted by the Extension Agronomists in the North Florida
REC, Quincy:
Dr. David Wright, dwright@ufl.edu
Dr. James Marois, jmarois@ufl.edu
Dr. Gueorgui Anguelov, ganguelov@ufl.edu
The 'ABCs' of forage establishment refers to those basic practices that if closely followed should result
in a successful pasture or hay field stand.
A= Adequate seeding depth. One of the most common mistakes when planting is to place the seed too
deep whether it is sexual (such as bahiagrass) or vegetative material (sprigs or tops). The reserves
contained in a seed or in the plant tissue of vegetative material are limited. If we plant too deep, the
seed energy and reserves will be exhausted just in trying to make it to the soil surface. If seeds are
placed at an adequate depth, the reserves will be enough for the plumule (future leaf) to reach the soil
surface where it will start photosynthesis and new growth.
B= Balanced seeding rate. If the seeding rate is too low, the stand will be thin, slender and weedy. On
the other hand, if the seeding rate is too high, there will be competition among the plants that you are
trying to establish, in addition to prohibitive costs. You want to have enough seed to make up for some
that will fall too deep in the soil, or will have unexpected conditions for germination.
C= Close seed-to-soil contact. The seed must absorb water from the soil after they are planted. If the
seed has poor contact with the soil, it will delay the water absorption, or the seed will dry after
absorbing water, resulting in faulty germination.
These are agronomic principles that, if followed, will help minimize stand establishment failure.
Dr. Yoana Newman
Extension Forage Specialist
ycnew@ufl.edu
Agronomy Notes Page 3
2500
2000
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VI
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-
A new weed was reported late last year near
Homestead, FL. After several consultations and
Mile-a-Minute Weed |
Photo: Ken Langeland
DNA analysis, it was determined that the plant is
Mile-a-minute (Mikania micrantha).
General description. Mile-a-minute is
a highly branched perennial vine. Leaves are
opposite and heart-shaped, 2-5 inches long and 1-3
inches wide, and taper to an acute point. In Florida,
it will likely flower in November and December,
with seed set occurring primarily in December.
Seeds are tufted, making them well-equipped for
wind dispersal. For pictures of this plant, please see
the DPI website at: http://www.doacs.state.fl.us/pi/
enpp/botany/mikania-micrantha.html.
How do I identify Mile-a-minute?
Identification of Mile-a-minute is complicated
by two very similar species that are present in
Florida. Climbing hempweed (Mikania scandens)
is a very similar species to Mile-a-minute. Mile-a-
minute tends to grow in disturbed habitats, has very
rapid growth, and has pale green or yellow-green
leaves with green petioles and white flowers.
Climbing hempweed grows primarily in natural
habitats, has medium green leaves with reddish
petioles and pinkish flowers. A third species,
Florida Keys hempvine (Mikania cordifolia), has
hairy leaves and stems and larger flower heads
compared to the other two species.
W hat is its habitat? Wet areas, forest
borders, clearings, canal banks, rivers,
roadsides, pastures, and other agricultural areas.
Generally invades disturbed areas. This plant does
not typically grow well in heavily shaded areas.
Is it a problem? Simply speaking, yes.
Mile-a-minute is a major environmental and
agricultural threat. Currently, it is recognized
globally as a top 100 invasive species. It is a
significant pest in plantation crop and commercial
forests from West Africa, India, and through
Southeast Asia and the Pacific Islands. It produces
tens of thousands fine, wind-blown seeds that aid in
its dispersal. It also reproduces asexually and can
regenerate from small cuttings.
Growth of Mile-a-minute is quite rapid, and can
grow at rates of at least 3 ft per week. This high
rate of growth allows Mile-a-minute to smother
existing vegetation quite quickly, thus reducing the
light reception of desirable species.
H ow is it controlled? Mechanical
control through cutting is not beneficial as it
can quickly regrow from cuttings. Uprooting and
digging, though very labor intensive, is the primary
mechanical method for control. We are suggesting
that all plant material be incinerated if plants are
removed by hand.
Chemical control methods in Florida will likely
include timely applications of glyphosate or
triclopyr; must be applied prior to flowering. A 3%
v/v solution of glyphosate in water or triclopyr at 1
to 2 pt/acre will likely be sufficient for control.
Excellent control of Mile-a-minute in Australia has
also been found with fluroxypyr (Vista) at 1 pt/acre.
Frequent scouting of the infested and surrounding
areas should be performed to treat any escapes or
regrowth.
Continued on Page 5
Agronomy Notes Page 4
Continued from Page 4
What do I do if I find this weed? Since this weed shows growth reminiscent of Old
World climbing fern that has invaded many natural areas in south Florida, it is imperative
that control efforts on individual populations begin immediately. To date, at least eleven separate
locations in the Homestead area have been identified, and with the wind-blown seeds, we are likely
to find more. If this weed is found in south Florida, please contact Florida Division of Plant
Industry at 888-397-1517.
Dr. Brent Sellers, Extension Weed Specialist
sellersb@ufl.edu
Range Cattle REC, Ona
Dr. Ken Langeland, Aquatic Weed Specialist
Center for Aquatic and Invasive Plants, Gainesville
gator8@ufl.edu
March 30, 2010
8:30 a.m. 4:00 p.m. EST
An opportunity for licensed pesticide applicators to earn CEUs will be held March 30, 2010 from 8:30
to 4:00 EST. The event will be conducted via polycom from participating UF/IFAS county extension
offices, several main campus sites and research and education centers. An applicator will be able to
attend any or all of the 6 sections for pesticide licensing recertification credit. A total of 6 FDACS-
approved CEUs are available for the entire day in the following categories:
Agricultural Row Crop Private Applicator Agriculture
Agricultural Tree Crop Right-of-Way Pest Control
Aquatic Pest Control Pest Control Operator-Lawn &
Demonstration and Research Ornamental
Forrest Pest Control Limited Commercial Landscape
Natural Areas Weed Management Maintenance
Ornamental & Turf Limited Lawn & Ornamental Pest
Credit for Certified Crop Advisors has been applied for and is pending approval. If interested in
attending, contact your local UF/IFAS county extension office or the UF/IFAS Pesticide Information
Office at (352)-392-4721 or http://pested.ifas.ufl.edu/.
Dr. Fred Fishel
Pesticide Information Director
weeddr@ufl.edu Agronomy Notes Page 5
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