Mineral nutrition contributes to...

Title: CitrusLines
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00090045/00016
 Material Information
Title: CitrusLines
Physical Description: Serial
Language: English
Publication Date: Fall 2010
Copyright Date: 2010
 Record Information
Bibliographic ID: UF00090045
Volume ID: VID00016
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.

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    Mineral nutrition contributes to plant disease and pest resistance
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Full Text

The Mission of UF/IFAS is to develop
knowledge in agricultural, human and
natural resources and to make that
knowledge accessible to sustain and
enhance the quality of human life.

Fal 01

p J
.I. A

IFAS Extension
Lake County Extension

Well as the summer comes to a close my children start getting excited about the holidays. Seems to come up
quicker and quicker every year. This Fall is a busy season like always, hopefully everyone will take the time
to continue to educate themselves by attending a few Extension programs. Researchers have been busy putting
your money to good use in the search for solutions to your production problems. Speaking of new problems
Black spot is the latest new disease to Florida, but additional exotic diseases are showing up in other states, the
time frame between diseases seem to be moving faster just like the calendar. I wish you all success as you
start harvesting the bounty of your labor this year!
Arrington, Director, in cooperation with the United States Department of Agriculture, publishes this information to further the purpose of the May 8
and June 30, 1914 Acts of Congress, and is authorized to provide research, educational information, and other services only to individuals and insti-
tutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, na-
tional origin, political opinions, or affiliations. Single copies of extension publications (excluding 4-H and youth publications) are available free to
Florida residents from county extension offices. Information about alternate formats is available from IFAS Communication Services, University of
Florida, PO Box 110810, Gainesville, FL 32611-0810.

Average and Deviation Probability Distribution Probability of Exceedance Last 5 Years
Ja FbMar Ap ay un Jul Au Sep Oct Nv IDec
Average 1.9 1.3 1.8 2.1 3.9 6.3 7.3 7.1 5.9 2.4 1.8 1.6
Deviation -0.7 -1.5 -1.9 -0.4 0.5 -1.4 -0.2 -0.6 -0.2 -0.4 -0.2 -0.9

iiom ;iiaic~

|ENSO Phase

fag~e 2

Florida Ag Expo



Personal Hygiene Training for packinghouses

Fort Pierce

Sept. 27th & Oct. 1st

LaNfa eeo psa h aii ca otne

A. Service of the Southeast Climate Consortium

Variable Type


Other events of possible interest

La Nina predicted for this coming winter;

translation high probability of warmer, drier weather

One of my favorite tools to evaluate the upcoming season is the AgroClimate website. They pro-
vide interesting charts and maps like the ones provided below and on the following page. The
ENSO cycle prediction which utilizes water temperature data collected in the Pacific Ocean pro-
vides a general overview of how climate data in a different parts of the world can be used to
forecast trends in weather patterns for our area. Weather is still obviously unpredictable on a

Freeze Probability (32 F)
1... Nina winters (Nov Mar)
g con- toon
a 1001- 20 as
20 or so so
30 01 40 00
soul.ac co
0 Tool so on
a so01 so on
M 9001- ice oa

Fage 3
day-to-day basis but knowing the overall
trends in climate could be helpful to agri-
cultural producers. With generally
warmer temperatures predicted for this
season one would suspect that new flush
and bloom could be a little earlier this Freeze Probability (28 F) ri
year, which may affect spray programs. La rena winters (Nov Mar)
So maybe getting your dormant spray for a 0 00 10 00
psyllid control would be a wise move for a in 01 20 00 ,
January and not waiting until February. soor .40 00

Additionally the probability that our area so or so on
will endure a freeze event of less than 32 so01. To Do N
degrees is 80% likely (better subscribe to [ ] 70 or so ol: W E
Weather Watch!) but the probability that a soor so co
we have a freeze event with temperatures a so ai 100 on S
of 28 degrees or less drops down to SO%
or less. More than likely we should not
have a major freeze event if temperatures respond as they have in the past La Nina events (yes I
am knocking on wood).

These types of weather patterns play a role
on chill hour accumulation which has an af-
fect on bud differentiation which plays a role
on the number of flowers and eventually the
number of fruit produced on a tree. Irriga-
tion in the spring during a La Nina event is
important to support fruit set and growth as
rainfall amounts are typically less than in a
normal year. Checking and cleaning out
your sprinkler systems might be a wise
move to ensure they are properly working
heading into a dry spring. Additionally, a
warm winter may allow for leafminer to get
an early start in late spring.



Many other agricultural crops are also af-
fected by La Nina events. In forestry where
they rely on rain to help newly planted trees, companies may decide to not replant well drained
sites until the following year when better conditions are present. In deciduous fruit crops low
chilling units can be a problem as they limit the potential size of the crop, although the warmer
weather usually allows for earlier production of fruit when these conditions exist there tends to
be when higher prices. The use of ENSO weather patterns is even receiving attention in non ag-
ricultural areas, such as ski resorts predicting how much snow fall they can expect when under
La Nina condition. Hopefully as the meteorologist continue to collect data and analysis on how
things like ocean temperatures affect regions of the world we can have even more accurate in-
formation on what general weather patterns will do. For more info: http://agroclimate.orq/

Fag~e 4

Citrus Health Management Ireas (CHII's)
Time Spray week of November 8th

Have you heard the latest acronym going around? CHMA or Citrus Health Management Areas
have been and are being implemented to help lower psyllid populations and limit the spread of
HLB. This is the same idea as area wide spraying. That is the more acreage sprayed around the
same time, the more effective the control of the overall psyllid population. This idea has been
presented here before (last Fall's newsletter). Seems most growers understand and have
adopted the practice of dormant applications (Jan-Feb) of pesticides for psyllid control. The Fall
spray gives great control reducing the population through the winter until the dormant spray.
This year Ben McLean who is representing the Citrus Research and Development Foundation's
(CRDF) effort to implement CHMA's and I are encouraging growers to spray for psyllids in our
area the week of November 8th.
Being that I represent 7 counties spread over a wide distance, it is very difficult for me to speak
to everyone via the telephone. I would encourage you to call your neighbors (local growers)
and encourage them to participate in these efforts! Cooperation is important in the war on HLB.
Now I know there are a lot of independent folks out there that may not want to participate in a
united effort. However, don't assume that they will not want to participate, call them and share
your plans to spray and encourage them to work with you and others. The Fall and dormant ap-
plication for psyllid control are the two of the most economical sprays due to the length of psyllid
control you will benefit from these sprays (2 sprays will control psyllids for half of the year). The
fall spray is done after the growing season is over and trees are "hardening off" for winter, it re-
duces the number of psyllids that will be over wintering in your grove. The dormant spray re-
duces those few psyllids that have survived the fall spray and the cold weather and brings you
through the spring flush with low psyllid population levels.
As part of the CHMA's, psyllid population monitoring will be done routinely (currently the USDA
is monitoring psyllid levels around the state) and more sprays will be coordinated. A website
with psyllid population levels around the state is in the development process. So be on the look
out for e-mails and updates in future newsletters for future CHMA spray coordination information.

CHRP Compliance for 2010-2011
The 2007-2008 Citrus Health Response Program (CHRP) Compliance Agreements and Business
Plans have been extended by the Florida Department of Agriculture and Consumer Services, Di-
vision of Plant Industry through the 2010-2011 citrus harvesting season. The following DACS
2007-2008 compliance agreements shall remain in effect until further notice from the Depart-
ment: Grower / Caretaker Compliance Agreement; Harvester / Handler Compliance Agree-
ment; Processor Compliance Agreement.
Grower Compliance Agreement Number (C/A Number) is required on all field trip tickets.
The Application for Participation is required for growers planning to ship to the EU in

S'agFe 5


Meet at Hendry County Extension

10-11:30 Research updates and grower
I1:30-Noon Lunch
12:20-2:00 Tour McKinnon Corp. Grove
2:20-3:30 Tour SWFREC research plots
I will be leaving the Mt. Dora area around 7AM
and can transport 3 riders. Please call and let
me know if you are interested.

Certified Crop Advisor CEli Day
Wednesday October 13th

For the first time Lake County will be a host
site for the Certified Crop Advisor CEU Day
which is broadcasted via polycom all over the
state. We will be meeting in the conference
room which is directly adjacent to my office at
the Agricultural Center in Tavares.
7:30 AM to 5:30 PM
Soil & Water Management (5 CEUs) &
Crop Management (5 CEUs)
On-site host: UF/IFAS Citrus Research and
Education Center in Lake Alfred, and offered
by videoconference
Speakers will deliver their presentation from the site
in their respective area.

Regular registration is $100
Lunch will be provided at all sites.

Please send the attached registration form to the Cit-
rus Research and Education Center, Lake Alfred.

Visit the CCA Seminar website at
for the specific program as it becomes available.

A pesticide license is required by any persons who apply or supervise the application of re-
stricted use pesticides for agricultural production. This certification requires a passing grade of
70% on the General Standards and Private exam. This certification must be renewed ever 4
years either by testing or by 8 CEU's.
There will be a review and exam in Orlando on December 9th. The review starts at 8:30 AM.
There is a $20 charge for the class. CEU's are available for the training session.
It is advisable to purchase the "Applying pesticides correctly" and "The private applicator train-
ing manual" from the IFAS bookstore on-line at www.ifasbooks.ufl.edu or by calling 800-226-
The private agricultural license itself cost $100 which does not have to be paid until after you
pass the exam. To register please call 407-2S4-9200.

S.W. Florida Field Trip
Friday October 8th

For the last few years we have traveled to Felda
and Immokalee to learn about research pro-
jects and observe grower blocks located in
those areas which have had high HLB incidence
compared to other areas of state. Local grow-
ers have found the trip very insightful and inter-
esting. Please let me know if you are attending
for lunch planning. Lunch is being sponsored
by Plant Food Systems.

PriateAgrculura Liens Reiew& Eam December 9th


S'agFe 6

Want to know what the weather prediction is for
this winter? Know when to run water for cold
protection and when to turn it off? What are cit-
rus leaf freezing points and how do I use that in-
formation? Plan on joining us to learn the answer
to all of these questions and more at the Agricul-
tural Center in Tavares on December 16th from
3PM to 6PM.
3:00-3:30 Check in & network with other growers
3:30-4:00 Predicted weather pattern for upcoming winter

CEli Day and WPS Training
Orlando November 4th

If you are in need of a lot of CEU's for your
pesticide license you are in luck. Twice a
year we offer a CEU Day. This Fall's CEU
Day will be held at the Orange County Exten-
sion office in Orlando. Registration is re-
quired. Multiple CEU's available. Please
call 407-284-9200 to register.
8:30 9:20 am TPDD and Fusarium Wilt: Some
Palm Diseases Never Go Away-
Dr. Monica Elliott, UF/IFAS Extension

9:20 10:10 am Turf Insect Resistance Man-
agement- Dr. Eileen Buss, UF/IFAS Exten-

10:30 am 12:30 pm Core Pesticide
Hands-on stations ES minute rotation

1:00 3:00 p.m. Worker Protection Stan-
dards/Train the Trainer -Ryan Atwood

Farm Worker Safety Day October 29

and its implications -Dr. Clyde Fraisse
Citrus leaf freezing values how are they deter
mined and what do they mean-Dr. Tim
FAWN Cold Weather Tool Kit-Rick Lusher
How to Make a Quality Weather Station-Chris
Cold Protection Decision Making- Ryan Atwood




As always with meal programs please register (see flyer) so

Do you have an agricultural operation? Are you doing all you can to ensure your employees
safety? Insurance companies and food safety auditors are looking to see if you are providing a
safe work environment. Don't you want to show them all your employee's certificates for attend-
ing the Farm Worker Safety Day course provide by UF/IFAS extension! Please register you or
your employees by using the form in the back of the newsletter. There is a $20.00 registration.

Sign in & Welcome
Worker Protection Standards & Pesticide
Safety Overview- Dr. Juanita Popenoe, UF
IFAS Lake County Extension Director
CPR-Dan Meehan, Health Central
Tractor and Equipment Safety-Chris Oswalt,
UF IFAS Polk County Extension

10:30-11:20 Proper transportation of Agricultural Equip-
ment- Lt. Amos Santiago Florida Department
of Transportation
11:20-11:50 General Traffic Safety-Lake County Sherriff
11:50-12:20 Safety Bingo-Ryan Atwood UF IFAS Lake
County Extension
12:20-1PM Lunch



Crop Cold Protection Class


Fag~e 7

I have included pictures of recent activities
at your extension program. If you have not
been coming, I wanted to show you what
you have been missing!
Left: A special thanks to Don Barwick General
Manager of Heller Brothers for giving up a Sat-
urday morning and hosting a 4H Citrus Tree
Project field trip at their packmghouse m Wm-
ter Garden. In attendance were 58 youths and
parents. It was a real educational experience
and the reviews were great! Thanks!!

Below: Dense root balls form under
drip emitters when grown usmg Open
Hydroponic System (OHS) techmques.
These techniques utilize pulsed drip

Above: Lee Jones and Pete Spyke give
their insights on growing citrus trees
using pulsed fertigation. They also dis-
cussed the goals of the trial located in

Left: A picture of a large Advance Pro-
duction System (APS) trial at Garden-
ier Fruit Company's grove in Indian-
town. APS utilizes higher density spac-
ing's with pulse fertigation with the idea
of growing a tree quickly and produc-
ing a return at a younger age.

PldllYOS Of recent Extension Activities

S'agFe 8

One of the great resources the Extension Service provides is the Electronic Database Information System or

AE1466 a 3-page ilusCtrate flact sheet by RdezaEsntihw owGoa Pstoin ytmsdt a

lihdb h FDpartment of Agrticultural an ilgianieneerin, August 2010.

http: //edis.ifas.ufl.edu/ae466

ecs ulished by the UF Department of Hortiultura Sci nces AugustolgJ 2010.

http: //edis.ifas.ufl.edu/hs1848

IPM146 aiu 18-age ilstrtd at shna emet byin NomnC dLeppaadKnehL ono I evsa

http: //edis.ifas.ufl.edu/in849

liF IFAS Electronic Database Information System or EDIS

Fage 9
the U.S. citrus juice market. Includes references. Published by the
UF Department of Food and Re source Economics, June 2010.

If you End these types of publications of interest and you would like to be notiHed when they become
available then you could subscribe using the directions below:
By the World Wide Web:
Direct your browser to http://lists.ifas.ufl.edu/archives/edis-update-1.html
Select "Join or leave the list (or change settings)"
Enter your full email address and name and click the "Join the List" button.
By email:
Send an email message to listserv@lists.ifas.ufl.edu.
leave the subject blank
in the body of the message, type "subscribe edis-update-l"
Send an email message to listserv@lists.ifas.ufl.edu.
leave the subject blank
in the body of the message, type "signoff edis-update-l"
For assistance, email EDIShelp@ifas.ufl.edu.

Sweet Orange Scab (SOS) recently discovered in Louisiana & Texas

Well we have another acronym to learn, SOS or Sweet Orange Scab (an exotic disease) has hit the U.S. citrus
industry, but has only been found in Louisiana & Texas to date. Thankfully it has not been found in Florida.
The causal agent of SOS is the fungus Elsinoe australis, which is similar to Elsinoe fawcetti, common citrus
scab, however it is a distinct species. SOS pathogen never infects leaves and only produces symptoms on fruit,
whereas citrus scab pathogen infects both leaves and fruit of susceptible varieties. The scab isolates can be
readily differentiated based on their abilities to infect different citrus cultivars. E. fawcetti incites lesions on
leaves of rough lemon, but E. australis does not. SOS mainly attacks all sweet oranges and some tangerine
cultivars. The damage produced is superHeial and does not affect internal fruit quality. Why be concerned?
Like so many of these diseases they present possible quarantine issues when shipping fruit overseas. For
those interested in learning more about this potential threat to fresh fruit in Florida please read: hty
edis.ifas.ufl.edu/pp l47.

. Photo from K.-R.
& Chung and L.W.
Tinuner'- Citrus Dis-
eases Exotic to Florida:
Sweet Orange Scab
(SOS) found at the link

If you have not yet had a chance to fill out this years survey. Please go
to :http://www.survevmonkev.com/s/citruslines and share your input to your
extension program. The survey takes about 1 minute to fill out.
New Insecticides & label changes for citrus:

Agri-FlexTM miticide/insecticide, from Syngenta Crop Protection, provides broad-spectrum 'trifecta' in-
sect control by protecting against Asian citrus psyllid, citrus leafminer and citrus rust mite. By combining
the active ingredients abamectin and thiamethoxam, Agri-Flex provides citrus growers with proven effi-
cacy and reliability in controlling these key destructive pests. For label go to:
Lorsban Advanced insecticide, a Dow product, recently changed its label to include applications with oil
and added psyllids as a pest. For label go to: http://www.cdms.net/LabelsMsds/LMDefault.aspx?
Intrepid 2F, a Dow product, recently added a spray drift management section to its label. For label go
to: http://www.cdms.net/LabelsMsds/LMDefault.aspxpd=6065&t=

Bayer Crop Sciences recently announced that all uses of Tenrik will be cancelled in 2011. This cancella-
tion includes citrus as well as all other crops. Limited supply of product will be available for use in late
2010 and early 2011 for citrus. No additional product is being manufactured. However, only about SO% of
the amount used in the 2009-10 application season will be available, thus if you used Temik last season
and wish to apply the material this year, you should be making arrangements with your supplier for mate-
rial allocation.

Think you haven't received my quarterly newsletter lately or just want to look something up but misplaced an
older copy. Archived copies can be found at:

The Vision for the University of Florida's Institute of Food and Agri-
cultural Sciences (UF/IFAS) is to increase and strengthen the knowl-
edge base and technology for:

* Expanding the profitability of global competitiveness and sustain-
ability of the food, fiber, and agricultural industries of Florida.
* Protecting and sustaining natural resource and environmental sys-
* Enhancing the development of human resources.
* Improving the quality ofhumanlife.

fa & e 8 E 0 / 5 5 US / ?L 5
Ryan Atwood
Extension Agent II
Multi County Fruit Crops
1981 Woodlea Rd
Tavares, FL 32778
Phone: 382-343-4101
Fax: 382-343-2627


Citrus Program Survey

Complete Address

Phone number 1 & 2

Additional numbers*

Additional phone numbers beyond two (extra charge of $25 a piece).

Email Addresses *

* Email of individuals that you want to receive the email updates.

I would like to subscribe to the Central Florida Weather Watch service and understand that I am
NOT to release the unlisted telephone number to anyone.



Enclosed is my check in the amount of $100 made payable to:
Weather Watch
1951 Woodlea Rd.
Tavares, FL 32778
The unlisted number will be sent prior to commencement of the service. We will begin Novem-
ber 15, 2010, and run until the threat of cold has passed (generally early to mid April).

Weather Watch


Locations of interest


IFAS Extension

Mineral Nutrition contributes to Plant Disease and Pest


The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and
other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex,
sexual orientation, marital status, national origin, political opinions or affiliations. U.S. Department of Agriculture, Cooperative Extension Service,
University of Florida, IFAS, Florida A. & M. University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Millie
Ferrer-Chancy, Interim Dean

Timothy M. Spann and Arnold W. Schumann2

Mineral nutrients are essential for the growth and
development of plants and microorganisms, and are
important factors in plant-disease interactions. How
each nutrient affects a plant's response to disease,
whether positively or negatively, is unique to each
plant-disease complex. This publication briefly
summarizes plant mineral nutrition and what is
known about how different nutrients affect different
types of plant diseases (fungal, bacterial, viral, and
soilborne) and pests.

In general, nutrient-pathogen interactions are not
well understood. Plant nutrients may affect disease
susceptibility through plant metabolic changes,
thereby creating a more favorable environment for
disease development. When a pathogen infects a
plant, it alters the plant's physiology, particularly
with regard to mineral nutrient uptake, assimilation,
translocation, and utilization. Pathogens may
immobilize nutrients in the soil or in infected tissues.
They may also interfere with translocation or
utilization of nutrients, inducing nutrient deficiencies
or toxicities. Still other pathogens may themselves
utilize nutrients, reducing their availability to the
plant and thereby increasing the plant's susceptibility
to infection. Soilborne pathogens commonly mfect

plant roots, reducing the plant's ability to take up
water and nutrients. The resulting deficiencies may
lead to secondary infections by other pathogens. Plant
diseases can also infect the plant's vascular system
and impair nutrient or water translocation. Such
infections can cause root starvation, wilting, and plant
decline or death, even though the pathogen itself may
not be toxic.

Fertilizer Nutrients

In addition to carbon (C), hydrogen (H), and
oxygen (0), which plants take up through the fixation
of carbon dioxide (CO2) via photosynthesis and
water (H20) uptake via roots, there are 13 mineral
nutrients that are essential for normal plant growth
and development. These nutrients, their general
relative abundance in plants, and their roles in plant
biology are listed in Table 1. These nutrients are often
viewed simply as plant food necessary for better plant
growth and yield. However, mineral nutrition also
influences growth and yield by affecting plant
resistance or susceptibility to pathogens and pests.

Although disease resistance is genetically
controlled, it is considerably mfluenced by

Mineal utrtio Cotribtesto lan DieaseandPes Reistnce2

environmental factors. Some disease resistance genes
in plants are only activated by specific environmental
stimuli. Mineral nutrition is an environmental factor
that can be easily controlled in agricultural systems,
the effects of which can be substantial.

In order to complement disease and pest control
methods, it is helpful to know how mineral nutrients
affect disease resistance in plants. Altering how plants
respond to pest or disease attacks can increase
resistance. There are two primary resistance
mechanisms that mineral nutrition can affect:

1. The formation of mechanical barriers, primarily
through the development of thicker cell walls.

2. The sulthesis of natural defense compounds,
such as phytoalexins, antioxidants, and
flavonoids, that provide protection against

nu3 ents


Figure 1. A schematic representation of the relative
balance of macronutrients, secondary nutrients, and
micronutrients for citrus. All of the nutrients are required
and must be present in the proper ratios to build a balanced
and complete pyramid. illustrationn: Arnold W. Schumann '

A balanced nutrient supply, illustrated for citrus
in the form of a "nutrient pyramid" (Figure 1),
ensures optimal plant growth and is usually
considered optimal for disease resistance as well. As
a rule, plants with an optimal nutritional status have
the highest resistance (tolerance) to pests and
diseases. Susceptibility increases as nutrient
concentrations deviate from this optimum. The
interaction between plants and disease organisms and
pests is complex. However, the roles of mineral

nutrients are well established in some areas of
host-disease interaction. The goal is to recognize
these interactions and see the possibilities and
limitations of disease and pest control by mineral
nutrition and fertilizer applications.

Fungal Diseases

Thinner, weaker cell walls leak nutrients from
within the cell to the apoplast (the space between
plant cells). This can create a fertile environment that
stimulates the germination of fungal spores on leaf
and root surfaces. Mineral nutrient levels directly
influence the amount of leakage as well as the
composition of what is leaked.

For instance, potassium (K) is essential for the
synthesis of proteins, starch, and cellulose in plants.
Cellulose is a primary component of cell walls, and K
deficiency causes cell walls to become leaky,
resulting in high sugar (starch precursor) and amino
acid (protein building blocks) concentrations in the
leaf apoplast. Calcium (Ca) and boron (B)
deficiencies also cause a buildup of sugars and amino
acids in both leaf and stem tissues. Nitrogen (N) is a
key component of amino acids: therefore, an
excessive supply of N can bring about higher amounts
of amino acids and other N-containing compounds in
plant tissues. These mineral imbalances lower
resistance to fungal diseases by creating a more
favorable environment for pathogens.

Most fungi invade the leaf surface by releasing
enzymes, which dissolve the middle lamella (the
"glue" that bonds adjacent cells). The activity ofthese
enzymes is strongly inhibited by Ca, which further
explains the close correlation between the Ca content
of tissues and their resistance to fungal diseases.

As stated previously, plant tissues contain and
produce a variety of defense compounds, which
hmder fungal attacks. Boron plays a key role in the
synthesis of these compounds. Borate-complexing
compounds trigger the enhanced formation of a
number of plant defense chemicals at the site of
. .
Infection. The level of these substances and their
fungistatic effect also decreases when the N supply is
too high.

Mineal utrtio Cotribtesto lan DieaseandPes Reistnce3

Mineral nutrition also affects the formation of
mechanical barriers in plant tissue. As leaves age, the
accumulation of silicon (Si) in the cell walls helps
form a protective physical barrier to fungal
penetration. Excessively high N levels lower the Si
content and increase susceptibility to fungal

Other micronutrients play a role in disease
resistance, too. Copper (Cu) is a plant nutrient that is
widely used as a fungicide. The amount required,
however, is very much higher than the nutritional
requirement. The action of Cu as a fungicide relies on
direct application to the plant surface and the
infecting fungi. From a nutritional perspective, Cu
deficiency leads to impaired defense compound
production, accumulation of soluble carbohydrates,
and reduced lignification (wood development), all of
which contribute to lower disease resistance.

Bacterial Diseases

Mineral nutrition affects susceptibility to
bacterial infections in much the same way that it
affects fungal infections. Potassium and Ca play key
roles in forming an effective barrier to infections.
When K, Ca, and, often, N levels are deficient, plants
are more susceptible to bacterial attacks. A frequent
symptom ofB deficiency is the development of
"corky" tissue along leaf veins and stems as a result
of the irregular (misshapen) cell growth that occurs
when B is deficient. These irregular cells are more
loosely bound than normal cells, essentially
producing wounds through which bacteria can

Adequate N levels increase plant resistance to
most bacterial diseases; however, excessive N can
have the opposite effect. As a rule, parasites that live
on senescing (dying) tissue or that release toxins in
order to damage or kill the host plants thrive in low N
situations. However, some bacteria actually increase
under high N conditions. These bacteria usually
depend on food sources from living tissue.

Disease relationships to K content are more
consistent. A review of 534 research articles found
that K reduced bacterial and fungal diseases 70% of
the time and insects and mites 60% of the time.
Unlike for other nutrients, the generalization can be

made for K that an adequate supply usually results in
an increased resistance to attack by all parasites and
pests. Potassium deficiencies created by
overapplication of dolomite or magnesium lower this

Ca affects the incidence of bacterial disease in a
variety of ways. First, Ca compounds play an
essential role in the formation of healthy, stable cell
walls. Adequate Ca also inhibits the formation of
enzymes produced by fungi and bacteria, which
dissolve the middle lamella, allowing penetration and
infection. Ca deficiencies trigger the accumulation of
sugars and amino acids in the apoplast, which lowers
disease resistance. Fruit tissue that is low in Ca is
also less resistant to bacterial diseases and
physiological disorders that cause rotting during

In general, similar principles govern the effect of
both micronutrients and macronutrients on disease
resistance: Any nutritional deficiency hinders plant
metabolism and results in a weakened plant, which
lowers disease resistance.

For instance, the lack of one small ounce of
molybdenum (Mo) per acre can lower disease
resistance by impeding the production of nitrate
reductase. This is an enzyme that contains two
molecules of Mo, and it is required to convert nitrates
to proteins. This example also illustrates the
importance of balanced nutrition-no nutrient
functions in isolation from the others. All essential
nutrients are critical for the proper metabolic
functioning of higher plants.

Viral Diseases

Nutritional factors that favor the growth of host
plants also favor virus multiplication. This holds true
particularly for N and phosphorus (P). However,
despite the rapid multiplication of the virus, visible
symptoms of the infection do not necessarily
correspond to an increase in mineral nutrient supply
to the host plant. In fact, symptoms of virus
infections sometimes disappear when N supplies are
large, even though the entire plant is infected. Visible
symptoms are dependent upon the competition for N
between the virus and the host cells. This competition

Mineal utrtio Cotribtesto lan DieaseandPes Reistnce4

varies with different diseases and can be influenced
by environmental factors, such as temperature.

Soilborne Fungal and Bacterial

Mineral nutrition affects soilborne diseases in
many different ways. A micronutrient-deficient plant
usually has depressed defense capabilities against
soilborne diseases. However, in some cases, nutrients
can have direct effects on soilborne pathogens. For
example, soil-applied manganese (Mn) can inhibit
the growth of certain fungi. Also, nitrites are toxic to
some Fusarium and Phytophthora species. Nitrites are
formed from ammonium nitrogen in the nitrogen
cycle as it is converted to nitrates by beneficial soil
bacteria. This two-step process is shown in Figure 2.

Atmospheric Nitrogenard I

"*** --** -

have on soilborne diseases are independent of soil
pH, further indicating the complex relationship of
mineral nutrition and disease.


Pests are organisms such as insects, mites, and
nematodes that are harmful to cultivated plants. In
contrast to fungal and bacterial pathogens, visual
factors such as leaf color are important factors in pest
susceptibility. Nutritional deficiencies discolor leaf
surfaces and increase susceptibility to pests. The
Asian citrus psyllid, Diaphorina citri, for example,
tends to settle on yellow reflecting surfaces (i.e.,
surfaces that appear yellow in color to the human

Three primary pest defenses of plants are:

1. Physical surface properties: color, surface
properties, hairs

2. Mechanical barriers: tough fibers, silicon
crystals, lignification

3. Chemical/biochemical: content of attractants,
toxins, repellents

Mineral nutrition affects all three defense
systems. Generally, young or rapidly growing plants
are more likely to suffer attack by pests than older,
slower-growing plants. Therefore, there is often a
correlation between N applications (stimulation of
growth) and pest attack. Boron deficiency reduces
the resistance to pest attack in the same ways it
reduces resistance to fungal infections. It is used in
the synthesis offlavanoids and phenolic compounds,
which are a part of the plant's biochemical defense


In the game of baseball, no home runs are scored
without touching first base. In the strategies of
integrated pest management, mineral nutrition is first
base. Optimizing mineral nutrient levels-especially
at critical stages when pest populations are
threatening-is both cost effective and agronomically

Figure 2. A schematic representation of the nitrogen cycle.
Ammoniacal nitrogen enters the system through the
fixation of atmospheric nitrogen by bacteria, the
decomposition of organic matter by bacteria and fungi, or
through fertilizer application. Ammonium is oxidized to
nitrite and then nitrate by bacteria through a process known
as nitrification. Plants take up (assimilate) nitrogen as
either ammonium or nitrate. illustrationn from Wikimedia
Commons, http://commons.wikimedia.org/).

The use of ammonium-based fertilizers can
increase the incidence of some diseases (e.g.,
Firsaristm and Phytophthora root rots), whereas
nitrate-based fertilizers generally have the opposite
effect. One explanation for this effect is how these
different N forms affect soil pH. Ammonium
fertilizers generally decrease soil pH over time,
particularly in soils with low suffering capacity, and
nitrate fertilizers tend to either slightly increase soil
pH or have no effect. However, some studies have
found that the effects these two N fertilizer forms

Mineal utrtio Cotribtesto lan DieaseandPes Reistnce5

Table 1. The 13 essential mineral nutrients required by all plants for normal growth and development

Nutrient Chemical Relative Function in plant
symbol abundance
Nitroen N100 rotens, minoacid

Acknowledg ments





Sign in & Welcome
Worker Protection Standards & Pesticide Safety Overview- Dr.
Juanita Popenoe, UF IFAS Lake County Extension Director
CPR-Dan Meehan, HealthCentral
Tractor and Equipment Safety-Chris OswaltUF IFAS Polk County
Proper transportation of Agricultural Equipment- Lt. Amos Sanitago
Florida Department of Transportation
General Traffic Safety-Lake County Sheriff
Safety Bingo-Ryan Atwood UF IFAS Lake County Extension
12:20-1PM Lunch




Make checks payable to:
Citrus Extension Program
Send to:
Maggie Jarrell
clo Lake County Extension
1951 Woodlea Road
Tavares, FL 34788
Phone 352-343-4101
Fax 352-343-2767

Phone Number:

Registration for this event is REQUIRED!!! Please register by October 27th!

2010 Farm Safety IDay

$20.00 per attendee


Environmental Quality Incentives Program

USDA Natura I Resources
Conservation Service

Imke & Sumter
Soil & Water Conservation Districts

Tavares Service Center
Renee Leech, District Conservationist
1725 David Walker Drive, Suite C
Tavares, FL 32778
Office: (352) 343-2481 ext. 3
Other programs offered:
Wetland Reserve,,Grassland Reserve,
Emergency Watershed, Conservation
Stewardship, & Conservation
Technical Assistance

The Environmental Quality
Incentives Program (EQIP) is a
voluntary conservation program for
farmers and ranchers that promotes
environmental quality in agricultural
production. EQIP offers financial and
technical assistance to participants to
install or implement stmetural and
management practices on agricultural
land. EQIP offers 2 to 10 year
contracts that provide financial
assistance to implement conservation
National, state, and local priorities
are used to guide which producers will
be selected to receive EQIP assistance.
The ranking system evaluates the
environmental benefit of each
application as it relates to the
conservation priorities.

All practices installed with program
assistance must be installed according
to NRCS standards and specifications.
Participants are expected to maintain all
practices throughout the life of the
practices as established by NRCS.
Annual status reviews are conducted to
ensure proper implementation and
contract compliance.
As with all NRCS programs, EQIP
is a voluntary program that is intended
to yield high quality, productive soils;
clean and abundant water; healthy
plant and animal communities; clean
air; an adequate energy supply; and
working farms and ranchland.

* Implement pest management plan
with recordkeeping
Animal & Plant Health
* Installation of cross fence, water
troughs, pumping plants, and
pipeline to facilitate rotational
* Eradication of invasive species (i.e.
TSA, cogongrass, etc)
Soil Erosion
* Install grade-stabilization strictures
* Strictures for water control (i.e.
flashboard risers)
Wildlife Habitat
* Prescribed burning
* Brush management

Water Quantity
* Convert inefficient irrigation
systems; such as seep irrigation to
drip tape irrigation systems, and
overhead sprinklers to micro-
irrigation. For nurseries;
conversion from sprinklers to ebb-
flow benches or capillary mats
* Retrofit inefficient spray jet
systems (i.e. replace PE tubing and
* Establish t ..1 < .r. r recovery
* Incentive for Irrigation Water
Management with Soil Moisture
Monitoring devices
Water Quality
* Implement nutrient management
plan with recordkeeping and soil

EQIP Resource Concerns


Dr. Jack Payne and "The Future of IFAS"

December 8, 2010

10:00 a.m. to 12:30 p.m.

Lake County Extension Office
1951 Woodlea Road
Tavares, FL 32778
Due to strong interest in this program and space size of room... registration is REQUIRED!!!

Jack Payne
Jack Payne is the Senior Vice President for Agriculture and Natural Resources at the
University of Florida. Appointed senior vice president in June, 2010, Payne is the
administrative head of the Institute of Food and Agricultural Sciences (lFAS) which includes
the College of Agricultural and Life Sciences, the School of Natural Resources and the
Environment, the School of Forest Resources and Conservation, elements of the College of
Veterinary Medicine, the Florida Agricultural Experiment Station, 13 Research and Education
Centers throughout Florida, and the Florida Cooperative Extension Service with offices in each
of the state's 67 counties.

Prior to his current position he served as the Vice President for Extension and Outreach at
lowa State University and before that was the Vice President and Dean for University
Extension at Utah State. Jack also has experience at two other land-grant institutions:
Pennsylvania State University, where he served on the faculty of the School of Forest
Resources, and, later, at Texas A&M University, where he served as a faculty member in the
Fisheries and Wildlife Department.

Please plan on joining us December 8, 2010 at the Lake County Extension Office, at 10:00 for
a presentation titled "The Future of IFAS" by our new Senior Vice President, Jack Payne. Get
his insights on our future and take this opportunity to let him know what you as a grower need
from UF/lFAS. Lunch will immediately follow this program.
Please detach and send registration for each attendee:

Maggie Jarrell
Lake County Extension Office
1951 Woodlea Road
Tavares, FL 32778
Or fax to 352-343-2767


City: State Zip:



Orange County Extension
Celeste White
6021 South Conway Road
Orlando, FL 32812
(407) 254-9200
Osceola County Extension
Jennifer Welshans

Orange County/UF/IFAS
Extension Education Center
6021 South Conway Road
Orlando, FL 32812
Office: (407) 254-9200
FAX: (407) 850-5125

Ornamental & Turf or
PriVate Applicator

Ag ric u Itural Pesticide

Thursday, December 9, 2010

8:00 am / Registration
8:30 am 12:00 pm / Reviews
1:00 pm / Exams

Orange County/UF/IFAS
Extension Education Center
6021 South Conway Road
Orlando, FL 32812
Office: (407) 254-9200
FAX: (407) 850-5125

CEU't Availthbi

Visit us at:


OFax OEmai

t C/Ck/MO

CEU's Available: 1.5 in General Standards (CORE), 2 in Private Applicator Agricultural, and
Ornamental & Turf

If you plan to take an exam, you should study the training manuals. They can be ordered at
(800) 226-1764 or http://ifasbooks.ufl.edu. In order to be certified, you will need to take the
General Standards CORE exam and the category license exam. No examine may receive
any examination without his or her government issued, valid, picture-bearing ID card (Florida
driver's license or government ID).

General Standards (CORE) The category is a basic examination that includes general knowledge
of proper pesticide use and pesticide safety. This exam is required for all licenses. Training
manual: Applying Pesticides Correctly SM 1.

Private Applicator Agricultural This license will be issued to persons who apply or supervise on
land owned or controlled by the private applicator or his/her employer the application of restricted
use pesticides for agricultural commodities for production such as vegetable, fruit, or cattle farm, sod
farm or nursery and greenhouse. Training Manual: Private Applicator Agricultural Pest Control -
SM 53.

Ornamental and Turf The license is for commercial or public applicators seeking certification and
licensure to apply pesticides for ornamental and turf pest control on a golf course, park, athletic field,
or cemetery. Training Manual: Ornamental and Turf grass Pest Management SM 7, Spray
Equipment and Calibration SM 38.

8:00 8:30 AM Registration
8:30 10:00 AM Review for the General Standards Exam
10:00 10:15 AM Break
10:15 11:00 AM Private Agricultural and Ornamental/Turf Review
11:00 AM 12:00 PM Calibration Review
12:00 1:00 PM Lunch on your own
1:00 4:00 PM All Exams Administered

Review & Exam: Ornamental & Turf or Private Applicator ? Registration Form

Agricultural Pesticide Licenses Review & Exam: Ornamental & Turf or Private
Applicator Agricultural Pesticide Licenses
Orange County/UF/IFAS Extension Education Center Orlando, Florida
I Thursday, December 9, 2010
Thursday, December 9, 2010
Register by: Monday, December 6, 2010
$20 non-refundable fee for the class
H t R i t

ow o egser:

1. Detach form and fill in your information as a as
2. Efee per-person for class, non-refundable.
3. Cash or checks only.
4. Checks made payable to 'Orange County Exten-
sion Fund'.
5. Mail registration form with payment to: Orange
County Extension, Commercial Horticulture
Services, 6021 S. Conway Rd., Orlando, FL 32812.

Note: Individuals needing special accommodations
should contact Celeste White at least five (5) working
days prior to the class at (407)254-9210.

Mailing Address

I Phone
I Fax
I Confirmation by:
Select section (s) y
I General Standards (
I Ornamental & Turf
Private Applicator Ag
CEUs Only 0

Amt Commen

ou are attending:


O Review ]Ea

ricultural 0 Review

O Exam

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