Y I UNIVERSITY o
UF FLORIDAgronomy Notes
IFAS Extension Agronomy otes
Volume 34:03 March 2010
Corn Pests With Planting Dates ............................... Page 2
Water Use Efficiency n Corn .................................. Page 2
Soil Temperature And Sorghum Planting Date .......... Page 2
Sorghum Seeding Rate ........................................ Page 3
Prowl H20 Now Labeled in Forage Bermudagrass ... Page 4
Pastora Herbicide ................................... ............Page 5
IFAS CEU Day .................................... Page 6
Cheap Pest Control ..................................... Page 7
C alendar............................................................... Page 4
Foliar Nutrition Of Crops ........................................ Page 7
The Institute of Food and Agricultural Sciences (IFAS) is an Equal Employment Opportunity-
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
(email@example.com); J. Ferrell, Weed Specialist (firstname.lastname@example.org); F. Fishel, Pesticide Information Officer
(email@example.com); B. Sellers, Extension Weed Specialist (firstname.lastname@example.org); D. Wright, Extension Agronomist
(email@example.com). Designed by Cynthia Hight (firstname.lastname@example.org.) 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.
Early planted corn has a better chance of avoiding fall armyworm and damaging disease epidemics
during its growth period. Planting in early March often results in high yield and quality but needs
irrigation in most years since May is typically a dry month when early planted corn silks and tassels. If
corn is planted into green cover crops, a soil insecticide is important for stand establishment. Corn is not
very susceptible to frost since the growing point remains under the soil surface until corn reaches about
12" high. The vegetative stage of growth can be slow from early planting in cool, wet soils but still fares
better in most years than corn planted in April and May if irrigated. Corn planted without irrigation may
do better if planted later due to summer rains that often occur in June.
Dr. David Wright, Extension Agronomist
North Florida REC, Quincy
Water requirements for corn can be significantly
higher where potassium in the soil is inadequate.
Potassium is important in corn for drought
tolerance since it impacts stomata opening in
leaves. A moderate potassium deficiency can result
in a loss of .2 inch more water loss per day through
the leaves than one with adequate potassium.
Follow soil tests for potassium use on all crops. A
lower rate can be used if fertilizer is banded in the
row vs. broadcast applications.
Dr. David Wright
There is a relatively wide range in planting dates for sorghum in the southeastern U.S., mainly because
sorghum germination is closely linked to soil temperature. For good stand development, it is important to
ensure that the soil temperature at the 2" depth is at least 650 F. Cold soils result in poor germination and
emergence and lead to poor stand development. Planting too early is one of the most common causes of
Plantings may begin in March in south Florida, early to mid-April in central and north Florida. Plantings
made after mid-June may have lower yields and experience more disease and insect pressure. Plantings
made after early July may produce very limited yields because of shortening daylengths. Early planted
silage sorghums will produce a second (ratoon) crop in Florida, but yields are generally less than the
Dr. Yoana Newman Dr. David Wright
Extension Forage Specialist Extension Agronomist
email@example.com North Florida REC
Agronomy Notes Page 2
Sudangrass and sorghum x sudan hybrids can be broadcast (B) or drilled. Hybrid forage sorghum
(single cut) is usually planted in wide (20 to 36 inch) rows (R) to facilitate harvest and in-season field
operations. The planter may need special plates or other modifications to handle sorghum seed.
Recommended seeding rate for forage sorghum intended for silage use in Florida and Georgia is 6-8
lb. per acre (R) and 10-15 lb per acre (B). Recommended seeding rate for sorghum-sudan hybrids in
Florida and Georgia is 8-20 lb per acre (R) and 25-30 lb per acre (B). Excessive seeding can increase
lodging (see Table below).
Seeding rate for sorghums in Florida
Species (Row planting) (Broadcast)
Lbs per acre Lbs. per acre
Hybrid Forage Sorghum 6-8 10-15
Sorghum x Sudan hybrids 8-20* 25-30
* Iffiner stems are desired, then choose the higher rate.
To calculate seeds per acre:
1bs rfnei ses ed mnbar of Seds
acre 1 of seed acrs
To calculate seeds per foot of row:
Lows Spacitn (M-cft) X 0,0Q03 X - -X I-od
S4 .60 1tbofs ss^
foot of row
Dr. Yoana Newman
Extension Forage Specialist
Agronomy Notes Page 3
For many years, high-quality bermudagrass hay producers have needed a preemergence herbicide for the
control of crabgrass, goosegrass, Texas panicum, sandbur and other summer annual grasses. BASF has
recently announced that Prowl H20 is now labeled for use on forage bermudagrass.
Prowl H20, active ingredient pendimethalin, has been registered in a multitude of crops for over two decades.
This herbicide is highly effective on annual grasses, but must be applied prior to grass seedling emergence.
Pendimethalin is only active at the root tip and has no postemergence activity. Therefore, the herbicide must
be applied prior to weed germination or no herbicide effect will be observed.
Currently, Prowl H20 is only labeled for use in dormant bermudagrass pastures and hay fields. Applications
to bahiagrass, limpograss, etc. is currently not allowed. However, it is expected that many more pasture
grasses will be added to the Prowl H20 in coming years.
The labeled application rate of Prowl H20 is 1.1 to 4.2 qt/A. Research has shown that the 1.1 qt/A rate is
generally not sufficient for season-long control while the 4.2 qt/A rate is often more than necessary.
Applications of 3 qt/A have shown to be satisfactory, but some late-season escapes should be expected.
Regardless, the price of Prowl H20 is near $35/gal, so over-application would be unattractive economically.
Currently, Prowl H20 is labeled only for applications to dormant bermudagrass and carries a 45 day hay
restriction as well as a 60 day grazing restriction.
This new use for Prowl H20 will be shown on a supplemental label and is available at http://www.cdms.net/
Dr. Jason Ferrell
Dr. Brent Sellers
Extension Weed Specialist Range Cattle REC, Ona
To follow the link, press "Ctrl" and put cursor over link, and "click."
Home and Garden Show, Tampa
Aquatic Weed Control Short Course, Coral Springs
Florida Beef Cattle Short Course, UF Gainesville, Hilton UF
Soil and Crop Science (SCSSF) meets jointly with the
Florida State Horticultural Society (FSHS), Plantation Golf Resort
Caribbean Food Crops Society meeting,
Boca Chica, Dominican Republic
Greater Everglades Ecosystem Restoration Meeting, Naples
Ecosvtem Restoration Conference (NCER), Baltimore, MD
Agronomy Notes Page 4
A New Tool for Grass Weed Control in Bermudagrass
A new herbicide mixture will soon be labeled for use in bermudagrass pastures and hayfields for grass weed
control. Pastora is a premix of nicosulfuron (56.2%) and metsulfuron (15%). Federal registration for this product
is expected near the beginning of the second quarter of this year.
The use rate for this herbicide will be 1.0 to 1.5 oz/acre per application, with a total maximum of 2.5 oz/acre/year.
The 1.0 oz/acre rate contains 0.035 lb ai nicosulfuron + 0.009 lb ai metsulfuron per acre. Increasing the rate to
1.5 oz/acre provides 0.052 lb ai nicosulfuron + 0.014 lb ai metsulfuron. The amount of metsulfuron in 1.0 and 1.5
oz/acre of Pastora is equivalent to applying 0.24 or 0.37 oz/acre of any 60DF formulation of metsulfuron
(MSM60, Accurate, Clean Pasture, etc). It is anticipated that there will be no grazing or haying restrictions when
using this herbicide.
i a'. -* .The primary target weed for this herbicide
Shas been sandbur, but this product will also
So P h control many other grass weeds including
dallisgrass, barnyardgrass, coast cockspur,
johnsongrass, vaseygrass, and several others.
Sq le aIn addition to grass weeds, several winter and
Sn summer broadleaf weeds can be controlled
with this herbicide. Dogfennel and tropical
soda apple will not be controlled with this
Apply Pastora postemergence when weeds
are small. Sandbur should be no taller than
1.5 inches for complete control; however,
applications to larger sandbur plants has been
shown to cause stunting and prevent
seedhead formation. Tall, dense stands of
, .bermudagrass will intercept much of the
herbicide spray. Therefore, Pastora should be
applied for annual grass weed control when
Vaseygrass is a common perennial grass weed in bermudagrass hayfields. Untreated bermudagrass is no taller than 4 inches
vaseygrass (A) compared with control ofvaseygrass 30 days after treatment with 1.3 following initial greenup or after cutting for
oz/acre ofPastora herbicide (B). hay. Considering that rainfall is usually
Photo: B. Sellers limited after initial greenup, applications may
need to be delayed for optimum control until
after the initial hay cutting and when rainfall is sufficient for active weed growth.
The nicosulfuron component of Pastora has been shown to provide suppression of vasseygrass. Nicosulfuron, at
rates equivalent to 0.7, 0.9 and 1.3 oz/acre of Pastora, was applied as vaseygrass was transitioning out of spring
dormancy. Vaseygrass control ranged from 75 to 79% control 30 days after treatment (DAT) (Figure 1), but
decreased to 65 to 75% by 60 DAT. Therefore, it looks like we will get suppression of vaseygrass if Pastora is
applied at initial greenup. We anticipate slightly better control of vaseygrass after full greenup, but applications
will need to be made fairly quickly due to the quick growth of vaseygrass.
Some bermudagrass injury should be expected, but the level of injury is much less than when Journey (imazapic
+ glyphosate) is utilized for sandbur or vaseygrass control. Injury will consist of some yellowing of leaf tissue.
More severe yellowing and some biomass reductions should be expected when using higher rates of Pastora.
Dr. Jason Ferrell
Dr. Brent Sellers
Extension Weed Specialist, Range Cattle REC Ona
Agronomy Notes Page 5
Need CEUs? An opportunity for licensed pesticide applicators to earn CEUs will be held:
March 30, 2010 8:30 am to 4:00 pm EST
The event will be conducted via polycom from participating UF/IFAS county extension offices 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
Agricultural Tree Crop
Aquatic Pest Control
Demonstration & Research
Forest Pest Control
Natural Areas Weed Management
Ornamental & Turf
Private Applicator Agriculture
Right-of-Way Pest Control
Pest Control Operator Lawn & Ornamental
Limited Commercial Landscape Maintenance
Limited Lawn & Ornamental Pest Control
Section Time Topic Title Speaker(s)
8:30 9:00 Register and convene at participating locations
1 9:00 9:50 How Different Kinds of Herbicides Work Greg MacDonald
2 10:05 10:55 Plant Anatomy: The Route of Herbicides Into and Within Clyde Smith
3 11:10 11:35 New Herbicide Registrations and Use Patterns Mike Netherland
11:35 12:00 Managing Herbicide Applications Against Development of Bill Haller
4 1:00 1:50 New Weeds to be on the Look-out for Colette Jacono
5 2:05 2:30 Integrating Biological Controls and Herbicides Jim Cuda
2:30 2:55 What is NPDES and How it May Affect Herbicide Applicators Tina Bond
6 3:10 3:35 Which Herbicide to Use Jason Ferrell
3:35 4:00 Minimizing Non-target Herbicide Effects Ken Langeland
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 http://solutionsforvourlife.ufl.edu/map/
Dr. Fred Fishel
Pesticide Information Director
Agronomy Notes Page 6
Pests are a leading cause of yield losses in all Florida
crops. One of the cheapest methods of pest control is
use of rotation. Even though this is something that
growers have known about for hundreds of years, we
often don't fully appreciate the impact it can have on
following crops since crop yield declines are often
gradual. Cotton and peanuts make a good rotation for Photo: Tyler Jones, IFAS Communications
each other but fields need to be out of peanuts for
more than one year. Grass crops like bahiagrass make an excellent rotation for most crops and often
result in more profit after 2 years of bahiagrass than could be made in 3-4 years in a standard rotation.
Peanuts and soybeans do not need to be in the same rotation unless there is at least two years between
Dr. David Wright
The majority of plant nutrients are taken up through the root system and that is the most efficient
method of nutrient uptake. Leaf absorption of nutrients is not the desired way of fertilizing crops since
the primary purpose of leaves is for photosynthesis. However, in certain situations micronutrients
become limiting to crop growth and may exhibit discoloration or slow growth and can be corrected with
foliar applications. In these situations foliar applications may be appropriate.
Macro-nutrient deficiencies can seldom be solved with foliar applications due to the total amount of
nutrients needed by the plant. Urea has often been used in cotton during bloom period but has not shown
yield advantages in Florida over soil applications during squaring or early bloom. Zinc and Manganese
deficiencies have been overcome on corn and soybeans in Florida with foliar applications as well as
boron on peanut. There are ways to make the applications more efficient including: applications made in
the early morning or late evening, apply when temperatures are less than 850 F, apply when relative
humidity is higher than 70%, make applications to youngest tissue that is actively growing, etc.
Listed below are the foliar absorption rankings of nutrients which would relate to the ability for the
plant to overcome deficiencies due to foliar applications.
Dr. David Wright, Extension Agronomist
North Florida REC, Quincy
Agronomy Notes Page 7