• TABLE OF CONTENTS
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 Step 1. Crop rotation
 Step 2. Soil tillage
 Step 3. Fertilizer relationships...
 Step 4. Seed treatment
 Step 5. Resistant varieties
 Step 6. Planting date and depth...
 Step 7. Use of foliar applications...
 Table 2: Information related to...
 Figure 1: Growth stages in...






Group Title: Plant protection pointers/Extension plant pathology reports
Title: Disease control program for small grains
CITATION PAGE IMAGE ZOOMABLE PAGE TEXT
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00066911/00001
 Material Information
Title: Disease control program for small grains
Series Title: Extension Plant Pathology Report 27
Translated Title: Plant Protection Pointers ( English )
Physical Description: Book
Language: English
Creator: Kucharek, Tom
Publisher: Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida
Publication Date: 2003
 Subjects
Spatial Coverage: North America -- United States of America -- Florida
 Notes
Funding: Florida Historical Agriculture and Rural Life
 Record Information
Bibliographic ID: UF00066911
Volume ID: VID00001
Source Institution: Marston Science Library, George A. Smathers Libraries, University of Florida
Holding Location: Florida Agricultural Experiment Station, Florida Cooperative Extension Service, Florida Department of Agriculture and Consumer Services, and the Engineering and Industrial Experiment Station; Institute for Food and Agricultural Services (IFAS), University of Florida
Rights Management: All rights reserved by the source institution and holding location.

Table of Contents
    Step 1. Crop rotation
        Page 1
    Step 2. Soil tillage
        Page 1
    Step 3. Fertilizer relationships with diseases of small grains
        Page 2
    Step 4. Seed treatment
        Page 2
    Step 5. Resistant varieties
        Page 3
    Step 6. Planting date and depth of planting
        Page 3
    Step 7. Use of foliar applications of fungicides for the suppression of foliar diseases of small grains
        Page 4
    Table 2: Information related to fungicides labeled for use on small grains produced for grain
        Page 5
    Figure 1: Growth stages in cereals
        Page 6
Full Text
















Plant Protection Pointers

EXTENSION PLANT PATHOLOGY REPORT NO. 27
GAINESVILLE, FLORIDA, SEPTEMBER, 2003

DISEASE CONTROL PROGRAM FOR SMALL GRAINS

By Tom Kucharek

Numerous diseases occur in small grains in Florida. Plant Pathology Fact Sheets numbers 38
and 53 contain information on the life cycles of the organisms that cause diseases of small grains and
they contain color photographs of the most common diseases of small grains in Florida. This publi-
cation provides information on specific tactics used for suppressing the common plant diseases.

Sequential Control Practices for Diseases of Small Grains

Step 1. CROP ROTATION
It is best not to plant small grains on the same land in sequential years. However, with the
decline of available land for crop production, rotation may be difficult. Possibly you can alternate
different small grains on the same land from year to year because certain diseases of one small grain
crop do not occur on other species of small grains. For example, glume blotch of wheat does not
occur in oats or rye. Also, soilborne wheat mosaic virus infects wheat, but not oats or rye. Soilborne
mosaic viruses of oats and rye have been found in Florida, but up to this time, they have been incon-
sequential in commercial settings. The planting of soybeans or cotton or other summer crops be-
tween the winter small grains season is double cropping and not crop rotation. Crop rotation relates
to years not crops within a year.

Step 2 SOIL TILLAGE
Where conventional plowing and disking is used prior to planting small grains, the old crop
debris needs to decompose for approximately 30 days so that beneficial organisms in the soil are
allowed to build up. Planting into green manure before decomposition is likely to result in develop-
ment of seeding blights from organisms such as Rhizoctonia spp. Planting into a stale seed bed with
surface debris from previous crops has been successful provided good seed to soil contact is
achieved and the small grain seed is not planted more than and 1" deep. The seed should have a
fungicide seed treatment.


1




















Plant Protection Pointers

EXTENSION PLANT PATHOLOGY REPORT NO. 27
GAINESVILLE, FLORIDA, SEPTEMBER, 2003

DISEASE CONTROL PROGRAM FOR SMALL GRAINS

By Tom Kucharek

Numerous diseases occur in small grains in Florida. Plant Pathology Fact Sheets numbers 38
and 53 contain information on the life cycles of the organisms that cause diseases of small grains and
they contain color photographs of the most common diseases of small grains in Florida. This publi-
cation provides information on specific tactics used for suppressing the common plant diseases.

Sequential Control Practices for Diseases of Small Grains

Step 1. CROP ROTATION
It is best not to plant small grains on the same land in sequential years. However, with the
decline of available land for crop production, rotation may be difficult. Possibly you can alternate
different small grains on the same land from year to year because certain diseases of one small grain
crop do not occur on other species of small grains. For example, glume blotch of wheat does not
occur in oats or rye. Also, soilborne wheat mosaic virus infects wheat, but not oats or rye. Soilborne
mosaic viruses of oats and rye have been found in Florida, but up to this time, they have been incon-
sequential in commercial settings. The planting of soybeans or cotton or other summer crops be-
tween the winter small grains season is double cropping and not crop rotation. Crop rotation relates
to years not crops within a year.

Step 2 SOIL TILLAGE
Where conventional plowing and disking is used prior to planting small grains, the old crop
debris needs to decompose for approximately 30 days so that beneficial organisms in the soil are
allowed to build up. Planting into green manure before decomposition is likely to result in develop-
ment of seeding blights from organisms such as Rhizoctonia spp. Planting into a stale seed bed with
surface debris from previous crops has been successful provided good seed to soil contact is
achieved and the small grain seed is not planted more than and 1" deep. The seed should have a
fungicide seed treatment.


1








2


With the increased use of minimum tillage and the concomitant reduction in sub-soiling with
some sort of deep ripping device, hard pans in soils have commonly developed. This author believes
that the presence of hardpans is one of the main factors interfering with lush fall growth of the small
grains that are planted for winter grazing. Root systems of young plants are not able to penetrate the
hardpan. Also, the hardpan becomes a site for salt accumulation which further interferes with nor-
mal root elongation. Roots of small grains are capable of penetrating five or more feet into the soil if
allowed to do so. Roots that are stressed from mechanical barriers or other factors are more likely to
become infected with root-rotting fungi such as Helminthosporium spp. (Bipolaris spp). Also,
disruption of hard pans allow roots to grow into deeper water sources during the spring if rainfall is
inadequate.

Step 3. FERTILIZER RELATIONSHIPS WITH DISEASES OF SMALL GRAINS.
Excessive levels of nitrogen have been related to higher severities of rust diseases and pow-
dery mildew of wheat. Excessive levels of phosphorous in the soil have been related to higher
severities of glume blotch. Practically speaking, variables such as varieties and planting dates are
more influential on levels of diseases than amounts of fertilizer. Certainly excessive use of nitrogen
should be avoid because of cost and the likelihood of lodging.

Step 4. SEED TREATMENT
The primary purpose of seed treatment is to protect the seed and emerging seedling from
infection by soil-inhabiting fungi such as Rhizoctonia solani, Fusarium spp., and Pythium spp.
These fungi are not typically transmitted by seed.

Captan and thiram are non-systemic, contact-type, somewhat broad-spectrum seed treat-
ment fungicides that reduce infection to a modest degree before the emergence of seedlings.

Carboxin (Vitavax) provides systemic protection for a short period of time beyond emer-
gence of the seedlings. Carboxin is particularly effective against Rhizoctonia spp., but it provides no
protection against infection from Pythium spp. Carboxin also reduces seedborne smut, but it is best
not to plant seed that was produced in fields with smut.

Metalaxyl-M (or metalaxyl, formally mefenoxam), is particularly effective for suppression of
diseases caused by Pythium spp. but not for diseases caused by other pathogens. Metalaxyl M is sold
under the trade names of Apron and Allegiance. Like carboxin, it is systemic and provides protec-
tion beyond emergence for a short period of time. Most formulations of Metalaxyl-M as seed treat-
ments are labeled for use in commercial seed-treating facilities, but Allegiance LS (a 1.63 lb/gal
formulation) can be used in the hopper box. at 1.2 fl oz/100# of small grain seed.

NEVER USE TREATED SEED FOR FOOD OR FEED FOR MAN OR BEAST. TREATED
SEED IS CLASSIFIED AS A PESTICIDE, BY LAW.








2


With the increased use of minimum tillage and the concomitant reduction in sub-soiling with
some sort of deep ripping device, hard pans in soils have commonly developed. This author believes
that the presence of hardpans is one of the main factors interfering with lush fall growth of the small
grains that are planted for winter grazing. Root systems of young plants are not able to penetrate the
hardpan. Also, the hardpan becomes a site for salt accumulation which further interferes with nor-
mal root elongation. Roots of small grains are capable of penetrating five or more feet into the soil if
allowed to do so. Roots that are stressed from mechanical barriers or other factors are more likely to
become infected with root-rotting fungi such as Helminthosporium spp. (Bipolaris spp). Also,
disruption of hard pans allow roots to grow into deeper water sources during the spring if rainfall is
inadequate.

Step 3. FERTILIZER RELATIONSHIPS WITH DISEASES OF SMALL GRAINS.
Excessive levels of nitrogen have been related to higher severities of rust diseases and pow-
dery mildew of wheat. Excessive levels of phosphorous in the soil have been related to higher
severities of glume blotch. Practically speaking, variables such as varieties and planting dates are
more influential on levels of diseases than amounts of fertilizer. Certainly excessive use of nitrogen
should be avoid because of cost and the likelihood of lodging.

Step 4. SEED TREATMENT
The primary purpose of seed treatment is to protect the seed and emerging seedling from
infection by soil-inhabiting fungi such as Rhizoctonia solani, Fusarium spp., and Pythium spp.
These fungi are not typically transmitted by seed.

Captan and thiram are non-systemic, contact-type, somewhat broad-spectrum seed treat-
ment fungicides that reduce infection to a modest degree before the emergence of seedlings.

Carboxin (Vitavax) provides systemic protection for a short period of time beyond emer-
gence of the seedlings. Carboxin is particularly effective against Rhizoctonia spp., but it provides no
protection against infection from Pythium spp. Carboxin also reduces seedborne smut, but it is best
not to plant seed that was produced in fields with smut.

Metalaxyl-M (or metalaxyl, formally mefenoxam), is particularly effective for suppression of
diseases caused by Pythium spp. but not for diseases caused by other pathogens. Metalaxyl M is sold
under the trade names of Apron and Allegiance. Like carboxin, it is systemic and provides protec-
tion beyond emergence for a short period of time. Most formulations of Metalaxyl-M as seed treat-
ments are labeled for use in commercial seed-treating facilities, but Allegiance LS (a 1.63 lb/gal
formulation) can be used in the hopper box. at 1.2 fl oz/100# of small grain seed.

NEVER USE TREATED SEED FOR FOOD OR FEED FOR MAN OR BEAST. TREATED
SEED IS CLASSIFIED AS A PESTICIDE, BY LAW.









3


Step 5 RESISTANT VARIETIES


Resistant varieties are not available for all diseases. However, efforts have been made by
plant breeders associated with universities and commercial companies to develop varieties that have
resistance to some of the common diseases. Varieties listed in Table 1 have resistance to certain
diseases and are agronomically acceptable for use in north Florida.


Table 1. Reaction of varieties to common diseases in Florida.

op Variety Leaf Rust* Powdery Soilborne wheat
Crop Variety Leaf Rust* mle m
mildew mosaic virus
Wheat AGS 2000 R R S
AGS 2485 MIR R S
NK Coker 9152 R R R
NK Coker 9663 R S R
USG 3209 MIR R R
Pioneer 26R61 R R R
Pioneer 2684 S R ?
Pioneer 2691 MVR MR ?
Agripro R R R
Crawfo rd


Triticale Sunland R R R


Oats Horizon 314 MIR NP** ANPA*
Horizon 474 R NTP NP
Chapman S NP NP
Plot Spike R NP NP
LA9339
Secretariat MS NP NP
LA495
Harrison S NP NP
LA 604 R NP NP


Rye Wrens 96 R R NP

For oats, the leaf rust organism is called crown rust and is a different species than the one that
infects wheat.
** Not pertinent


In addition, the oat varieties, Arkansas Co. 604, Horizon 314, and Chapman have some (fair) resis-
tance to barley yellow dwarf virus which is spread by aphids


Step 6. PLANTING DATE AND DEPTH OF PLANTING


To minimize seedling blights and root rots caused by Pythium spp., planting of small grains
should be delayed until the end of October and preferably until the end of November. In order to
establish winter grazing for cattle, planting in October is necessary, but the risk from Pythium spp.-









3


Step 5 RESISTANT VARIETIES


Resistant varieties are not available for all diseases. However, efforts have been made by
plant breeders associated with universities and commercial companies to develop varieties that have
resistance to some of the common diseases. Varieties listed in Table 1 have resistance to certain
diseases and are agronomically acceptable for use in north Florida.


Table 1. Reaction of varieties to common diseases in Florida.

op Variety Leaf Rust* Powdery Soilborne wheat
Crop Variety Leaf Rust* mle m
mildew mosaic virus
Wheat AGS 2000 R R S
AGS 2485 MIR R S
NK Coker 9152 R R R
NK Coker 9663 R S R
USG 3209 MIR R R
Pioneer 26R61 R R R
Pioneer 2684 S R ?
Pioneer 2691 MVR MR ?
Agripro R R R
Crawfo rd


Triticale Sunland R R R


Oats Horizon 314 MIR NP** ANPA*
Horizon 474 R NTP NP
Chapman S NP NP
Plot Spike R NP NP
LA9339
Secretariat MS NP NP
LA495
Harrison S NP NP
LA 604 R NP NP


Rye Wrens 96 R R NP

For oats, the leaf rust organism is called crown rust and is a different species than the one that
infects wheat.
** Not pertinent


In addition, the oat varieties, Arkansas Co. 604, Horizon 314, and Chapman have some (fair) resis-
tance to barley yellow dwarf virus which is spread by aphids


Step 6. PLANTING DATE AND DEPTH OF PLANTING


To minimize seedling blights and root rots caused by Pythium spp., planting of small grains
should be delayed until the end of October and preferably until the end of November. In order to
establish winter grazing for cattle, planting in October is necessary, but the risk from Pythium spp.-








4


induced diseases is high. Earlier plantings of small grains should be done with seed treated with
either Apron or Allegiance. See Step 4 on seed treatment.
To minimize seedling blights, planning depth should not exceed 1" of depth.


Step 7. USE OF FOLIAR APPLICATIONS OF FUNGICIDES FOR SUPPRESSION OF
FOLIAR DISEASES OF SMALL GRAINS.

In select situations, the use of a fungicide spray program can aid significantly in suppression
of foliar diseases of small grains and increased yields. The primary target diseases are leaf rust
glume blotch, and Helminthosporium leaf spot (Bipoloris sorokinianum) of wheat. Helmintho-
sporium leaf spot of rye and triticale have also been successfully suppressed with aerially applied
fungicide treatments.

The primary ingredient for success with this program is to use a timely spray program and an inex-
pensive fungicide. Specifications about some labeled fungicides for use on small grains are presented
in Table 2. Mancozeb (Dithane M45, Dithane 75 Rainshield DF, Manex II, Manzate 75 DF,
Manzate 80 WP, Penncozeb 75DF, or Penncozeb 80WP) has been tested extensively in Florida and
should be at least part of the spray program.

The first of three applications should be applied during FEEKE'S GROWTH STAGE 7 or 8 (See
Figure 1). SPRAY PROGRAMS INITIATED AFTER GROWTH STAGE 8 ARE NOT LIKELY TO
BE EFFECTIVE. Labels of some fungicides will sometimes refer to the Zadok's growth stage or the
Feeke's scale or both. The Zadok's scale is not easy to use because the small grain may grow
through more than one its stages within one day. The Feeke's scale is more practical to use for
commercial production. The second and third spray applications, if used, should be applied on 10-14
day spray intervals. If a rainy front is forecasted to arrive by the 11th day after the previous applica-
tion, apply the next scheduled spray on the 10th day after the previous spray. If a rainy weather front
is forecasted to arrive the 13th day after the prior application, apply the next spray on the 12th day
after the previous spray. THE KEY IS TO HAVE THE FUNGICIDE ON THE LEAVES DURING
THE RAIN EVENT NOT AFTER THE RAIN. The addition of an adjuvant that contains both a
spreader and sticker (e.g. Latron CS-7) to the spray mix is important to hold the spray on the leaves
where a mancozeb product is used.









5


Table 2. Information related to fungicides labeled for use on small grains produced for
grain. The pertinent diseases are Helminthosporium leaf spot (Bipolaris), glume blotch, leaf
rust, and powdery mildew. Glume blotch and powdery mildew are problems on wheat, but
not the other three small grains in Florida.

Maximum
Fungicide Common Names Crops RateAce Restrictions
Rate/Acre

Common Trade Names Wheat Triticale Rye Oats

Mancozeb Dithane M45 Yes Yes Yes Yes 2.0 Lbs Limit is 3 appl,
Penncozeb, or & 3 times the
Manzate 80WPS single
appl.rate/crop.
Do not graze
treated forage.

Dithane F45 or Yes Yes Yes Yes 1.6 qts
Manex II

Dithane 75 DF Yes Yes Yes Yes 2.11bs

Penncozeb Yes Yes Yes yes 2.01bs
75DF

Azoxy- Amistar 80 DF Yes Yes No No 4.0 oz Limit is 2 appl.
strobin & 0.51b/crop/
season. Do not
harvest treated
wheat for forage.
Do not apply
within 45 days
of harvest for
grain and straw.

Pyraclo- Headline Yes No Yes No 9.0 Fl. oz Limit is 2 appl.
strobin 2.09DF & 18 fl oz/crop.
Do not harvest
wheat hay within
14 days of last
application.

Propicon- Tilt 3.6E Yes No Yes Yes 4 fl oz Limit is 1
azole appl.not to be
applied within
40 days of
harvest. Do not
feed treated
wheat or rye to
livestock. Only
oat forage &
hay maybe fed.
Harvested straw
of wheat, rye or
oats can be
used for
bedding or
feed.









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