UF FLORID Production Times
IFASExtension Nursery Edition
Volume 16, Number 1
See the newsletter in color at:
Maranta mite damage on Stromanthe
Chilli thrips damage on viburnum and
Plant Clinic Problems -
Maranta mite, Chilli thrips
The Maranta mite caused the de-
cline of Maranta in the market
and now is attacking Stromanthe.
There is no really effective pesti-
cide that can be used under green-
house conditions. In the field you
can use Thiodan. Avid and Pylon
provide some control.
Chilli thrips continue to attack
Indian Hawthorn, Viburnum, Ar-
boricola, Blueberries and most
everything else. Thrips controls
and more can be found at
For all the Plant Clinic diagnoses:
iiltiirp/nlant rlinir/indlp dhtml
Production Times is going to a new format. Twice a year, in the spring
and winter, the newsletter will focus on nursery issues and be edited by
Juanita Popenoe. Twice a year in summer and fall the focus will be on
greenhouse foliage issues and Lelan Parker will be the editor.
Upcoming Educational Programs
For more information and links to most programs and agendas go to:
http://cfextension.ifas.ufl.edu or the UF Extension Calendar at http//
Turf & Ornamental Pest Management Workshop. January
10, 2009. Orange County Extension Office, Orlando. Contact Celeste
White at (407) 254-9200.
AGRItunity 2009. Small Farms Program. January 24, 2009, Her-
nando County Fairground south of Brooksville. Contact Stacy Strickland
or Donna Peacock (352) 754-4433.
Limited Certification Pesticide Applicator Training and
Exams. Landscape Maintenance License. January 31, 2009. Orange
County Extension, Orlando. Contact Celeste White at (407) 254-9200.
Fertilizers and Alternatives. February 3, 2009, 5-7 pm, Lake
County Extension Office, Tavares. Free program, dinner included. Contact
Maggie Jarrell at (352) 343-4101.
Palm Management in the Florida Landscape. February 5-6,
2009. UF/ IFAS, Fort Lauderdale Research and Education Center, Davie,
FL. Contact Dr. Monica Elliott, at email@example.com or 954/577-6315.
Nursery Production School. February 17, 2009. 8:30 a.m.
p.m. Sumter County Extension Office, (352) 793-2728
Agricultural Risk Management & Crop Insurance. Febru-
ary 17, 2009, 5-7 pm, Lake County Extension Office, Tavares. Dinner in-
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eluded. Contact Maggie Jarrell at (352) 343-4101.
Private Applicator & Ornamental /Turf Pesticide License training & exam. Febru-
ary 19, 2009. Seminole County Extension Office, Sanford. Contact Richard Tyson at (407) 665-5554.
Dead Palms Tell No Tales Video Conference February 24, 2009. Lake County Extension Of-
fice, Tavares. Contact Maggie Jarrell at (352) 343-4101.
Integrated Pest Management Update March 4, 2009, MREC, Apopka. Contact Maggie Jarrell
at (352) 343-4101.
Websites to Checkout
Canna yellow mottle virus in 'Bengal
Tiger.' Symptoms are similar to nutri-
The University of Tennessee has a new Ornamental Pest and Disease
Update newsletter at http://soilplantandpest.utk.edu/pdffiles/
OPandDUpdates/dec2008.pdf. The latest edition has an interesting article
on canna virus, a new stink bug pest and the emerald ash borer.
If you would like to learn more about Phytophthora, Oregon State
Extended Campus in cooperation with the Oregon Department of
Agriculture has developed an online course for nursery growers. The
course is divided into three modules: Module 1-Biology, symptoms, and
diagnosis; Module 2-Disease management; Module 3- Phytophthora
ramorum (Sudden Oak Death). For more information go to:
Interested in reaching out to the younger generation through the web?
Check out http://www.hubspot.com/archive/facebook-for-business to
learn how to use Facebook to promote your business.
Weather The Neutral Pacific means more variable weather patterns and
greater likelihood of severe freezes. If you want to find out more about the
agricultural weather forecast, go to http://agroclimate.org/forecasts/
Production Times is brought to you by:
Juanita Popenoe, Ph.D.
Multi-County agent, Woody Ornamental Production
1951 Woodlea Rd.
Tavares, FL 32778
This material is provided as one of the many services relating to the educational programs offered
to you by this agency Our statewide network of specialists is prepared to provide current infor-
mation on agriculture, marketing, family and consumer sciences, 4-H, marine science, and related
fields We will be happy to help you with additional information upon request
Use of trade names in this newsletter does not reflect endorsement of the product by the Univer-
sity of Florida, Institute of Food and Agricultural Sciences, or the Florida Cooperative Extension
The Institute of Food and Agricultural Science (IFAS) is an Equal Employment Opportunity
Institution 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 US DEPARTMENT OF AGRICULTURE, FLORIDA COOPERATIVE
EXTENSION SERVICE, UNIVERSITY OF FLORIDA, IFAS, FLORIDA A & M
UNIVERSITY COOPERATIVE EXTENSION PROGRAM, AND BOARDS OF COUNTY
HortScience Research Summaries
By Juanita Popenoe
New light emitting diode (LED) lights (similar to
those new Christmas tree lights that are so bright and
do not get hot) offer a way to supplement or provide
light to plants within a very narrow range of wave-
lengths. LEDs have several advantages over tradi-
tional light sources: small size, durability, long oper-
ating lifetime, wavelength specificity, and relatively
cool emitting surfaces. The wavelengths are so spe-
cific that you must determine which you need to pro-
duce the best crop. As with other light sources, LEDs
can affect crop anatomy and morphology as well as
nutrient uptake and pathogen development. LEDs
may be used in future to control plant growth instead
of the plant growth regulators used today. Blue light
grown plants were more compact whereas red-light
grown plants were tall, and mixes of the lights al-
lowed the best growth. A regime could be designed
for each stage of development to get the type of
growth desired for best production.
Along similar growth control lines, research on pho-
toselective polyethylene greenhouse covering film
that limits light transmission to the wavelengths be-
tween 500 nm and 800 nm indicates that gardenia
plants rooted under this film were 69% shorter than
plants grown under normal polyethylene. Young pot-
ted plant growth was not as good under this film, but
if plants were rooted under the special film and then
transferred to the common film, the result was com-
pact, well-shaped plants.
High light levels during rooting and after transplant-
ing increased the quality of New Guinea impatiens
and petunias. They were shorter with a greater root
mass and flowered earlier. Increased light for woody
cuttings is best done after roots have initiated (to
avoid reduced rooting from loss of water stimulated
by high light levels). Some woody species like Japa-
nese maple and hibiscus do not respond to increased
light during propagation, so test before using in pro-
In a study to determine the effect of herbicide drift
on white oak seedlings at swollen bud, leaf unfolding
and expanded leaf growth stages, they found 2,4-D
and dicamba at leaf unfolding stage caused leaf cup-
ping, downward rolling of leaf margins, elongation
of leaf tips, leaf strapping with parallel veination and
initial leaf cupping followed by death of the growing
point. Glyphosate applied at either the leaf unfolding
or expanded leaf stage caused leaf yellowing and
browning and curling of leaves. Acetochlor and me-
tolachlor both caused leaf tatters malformed leaves
lacking tissue between veins when applied at the
leaf unfolding stage. They recommend that herbicide
applications near trees occur when the trees are dor-
mant and leafless or after the expanded leaf stage.
(This is much more difficult to time in Florida!)
Azalea lace bugs (ALB) feed by inserting their
mouthparts into the azalea plant's stomata. However
a study measuring stomata size in different cultivars
and comparing to ALB preference and damage found
no correlation. 'Fourth of July' was the least pre-
ferred by ALB, and 'Watchet' the most preferred in a
study of 33 cultivars. 'Fourth of July' has one of the
smallest average stomata size, but so does 'Delaware
Valley White', one of the more susceptible cultivars.
Therefore the mechanism for lace bug resistance is
not the stomata size and remains to be found.
ments no longer influenced plant growth.
Soil amendments for landscape trees and shrubs are
not recommended because they can limit root exten-
sion into the surrounding soil, but some recent re-
search from Washington State indicates that amend-
ments, or at least mulch, may be useful in some sites.
They studied the effect of no treatment, 3 inches of
compost applied to the surface, 3 inches of compost
incorporated by rototilling to a depth of 8 inches, 3
inches of bark mulch, surface applied compost + bark
mulch and incorporated compost + bark mulch over
five years. Their results show that Redosier dogwood
growth was best during the first 4 years with incorpo-
rated compost + bark mulch. Incorporated compost
had a greater effect than surface applied compost, but
both were beneficial in reducing soil density and
compaction and increasing water infiltration. Using
bark mulch with the compost made soil properties
even better. Both surface applied compost and bark
mulch increased water infiltration, meaning that sur-
face application of compost could provide benefits
where incorporation is not feasible. About half the
depth of surface-applied compost and bark mulch re-
mained 5 years after application. By year 5, treat-
Pine tree substrate (PTS, loblolly pine trees that are
chipped and hammer-milled to a desired particle size)
was shown to be an effective poinsettia potting me-
dia. This study compared the effect on poinsettia
growth of PTS milled to three different sizes (2.38
mm, 4.76 mm and 4.76 mm screen) to peat-lite me-
dia. Poinsettias were equal in quality to peat-lite
plants when grown in PTS with small particles (2.38
mm screen) or PTS with larger particles if peatmoss
was added at 25% and they were fertilized with 300
mg/L nitrogen. Dr. Beeson at MREC in Apopka is
doing similar research with woody shrubs and ex-
pects results by summer 2009.
INS it -.. a..
For more details on these research summaries see the
American Society for Horticultural Science publica-
tion HortScience, December 2008 or ask your exten-
Bark Cracking Problems?
By Juanita Popenoe
Many growers use Glyphosate
(Roundup) herbicide around their
woody plants. The demand for
faster-working glyphosate prod-
ucts and the fact that Roundup is
now off patent has led to the ge-
neric development of many differ-
ent formulations with different
characteristics. Growers got used
to using the original "classic"
Roundup, but now have to deal
with a much more potent chemi-
cal. New research by Dr. Hannah
Mathers at Ohio State University
on new formulations should send a
warning to all about the use of this
Bark cracking costs the U.S. nurs-
ery industry an estimated $6.6 mil-
lion annually, and even more in
landscape failures. In the past this
was thought to be caused by cold
injury, but Dr. Mathers' research
points to glyphosate with new sur-
factants that get it into thin or pig-
mented bark where it can remain
for years. It reduces cold hardiness
and causes other growth defects.
Surfactants break down the cuticle
of plants and increase the uptake
of chemicals they are formulated
with. Glyphosate does not last
long in soil, but once in the plant
is translocated to the roots where it
is stored and may last for years,
accumulating each year. It may
take up to two years before effects
of sub-lethal doses of glyphosate
can be seen. Effects can be witches
broom, stunting, bark cracking or
splitting, loss of apical dominance,
individual dead limbs, yellowing
and death. It is very difficult to
diagnose this problem because of
the varied symptoms and the
length of time it can take before
they are seen.
Glyphosate should be used only
when absolutely necessary around
a nursery. Pre-emergent herbicides
should be used to keep weeds out
of the nursery. If you find that you
have a weed emergency and need
to use glyphosate, use a product
that has no additives and be very
careful not to get the product near
thin and/or colored bark.
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