Title: Florida plant disease management guide
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Title: Florida plant disease management guide
Alternate Title: Ornamentals and turf
Fruit and vegetables
General plant pathology, field crops and pasture grasses, fungicides, adjuvants and application techniques
Physical Description: v. : ; 28 cm.
Language: English
Creator: University of Florida -- Dept. of Plant Pathology
Florida Cooperative Extension Service
Publisher: The Extension
Place of Publication: Gainesville Fla
Frequency: annual
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Subject: Plant diseases -- Periodicals -- Florida   ( lcsh )
Pesticides -- Periodicals   ( lcsh )
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Statement of Responsibility: Plant Pathology Dept., University of Florida and Institute of Food and Agricultural Sciences, Florida Cooperative Extension, University of Florida.
Numbering Peculiarities: Issued in three volumes: v. 1, General plant pathology, field crops and pasture grasses, fungicides, adjuvants and application techniques; v. 2, Ornamentals and turf; v. 3, Fruit and vegetables.
General Note: Description based on: 1999-2000.
General Note: "SP-52"
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Bibliographic ID: UF00053871
Volume ID: VID00035
Source Institution: University of Florida
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Resource Identifier: oclc - 44549741
lccn - 00229071
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Preceded by: Florida plant disease control guide

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PDMG-V3-27
UF UNIVERSITY of
UFFLORIDA
IFAS Extension



2007 Florida Plant Disease Management Guide: Pear

(Pyrus communis)1


Tim Momol, Laura Ritchie, and Hank Dankers2

BLACK ROT

Introduction

Black rot of pear occurs throughout the eastern
United States but is most severe in the southeast.
Losses from the disease come not only from fruit rot,
but from the weakening of trees due to limb cankers
and leaf spot-induced defoliation.

Symptoms

Leaf lesions begin as small purple flecks which
enlarge and develop a tan to brown center, giving a
"frog eye" appearance. Heavily infected leaves may
become chlorotic and abscise. Fruit symptoms from
direct infection begin as minute red flecks which
develop into raised purple spots bordered by a red
ring. Upon maturation of fruit the lesions will
enlarge and form a series of alternating black and
brown concentric rings (Figure 1).

Limb cankers begin as slightly sunken reddish
brown areas in the bark and can lead to a superficial
hardening of the bark or the canker may cause the


Figure 1. Black spot on pear fruit. Credits: Eugene
Kupferman, Washington State University

wood to crack open and die. Fruit may develop
rotting around the core, yet remain on the tree,
ripening 3-6 weeks before harvest and often dropping
before the rot appears on the surface.

Causal Organism

Botryosphaeria obtusa (anamorph Sphaeropsis
malorum) is the causal organism of black rot.
Pycnidia, commonly found on infected wood and


1. This document is PDMG-V3-27, one of a series of the Plant Pathology Department, Florida Cooperative Extension Service, Institute of Food and
Agricultural Sciences, University of Florida. Revised December 2006. Visit the EDIS Web Site at http://edis.ifas.ufl.edu.
2. Tim Momol, associate professor, Plant Pathology Department, North Florida Research and Education Center--Quincy, FL; Laura Ritchie, biologist, North
Florida Research and Education Center--Quincy, FL; Hank Dankers, senior biologist, North Florida Research and Education Center--Quincy, FL; Florida
Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611.
The use of trade names in this publication is solely for the purpose of providing specific information. UF/IFAS does not guarantee or warranty the
products named, and references to them in this publication does not signify our approval to the exclusion of other products of suitable composition.

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. Larry
Arrington, Dean






2007 Florida Plant Disease Management Guide: Pear (Pyrus communis) 2


fruit, are globose, solitary or botryose, and stromatic
with papillate ostioles. At maturity, conidia are
nonsepate, ovoid, melanized, with a rough or faintly
echinulate wall. Asci are bitunicate and eight-spored;
ascospores are fusiform and occasionally one-septate.
Pseudothecia are rare in the southeastern United
States.

Disease Cycle and Epidemiology

B. obtusa can survive between seasons in tree
cankers and mummified pears, providing an
early-season source of inoculum. Mummified fruit,
wounded bark, and fire-blighted twigs are rapidly
colonized by B. obtusa and provide inoculum during
the growing season. Conidia and ascospores are
released from fruiting structures during rainfall
throughout the year in the southern United States.
Infection can occur through stomata of leaves or fruit
(early season), and through wounds and cracks in the
fruit cuticles (later season).

Management

Throughout the season fire-blighted twigs should
be removed to lessen the colonization sites for B.
obtusa. Mummified fruit and dead wood should be
pruned and removed from the orchard or burned.
Black rot is best controlled through chemical
applications. See Table 1.

BOTRYOSPHAERIA ROT/WHITE
ROT

Introduction

Botryosphaeria rot, also referred to as Bot rot or
white rot, has symptoms similar to black rot. This
disease can have a severe impact in the southeast
United States. Extensive fruit losses (50%) have been
reported and cankers can cause the loss of scaffold
limbs and possible tree death.

Symptoms

Fruit lesions begin as small, slightly sunken
brown to tan spots, often surrounded by a red halo
(halo may appear purple to black on red cultivars).
The rotted area extends in a cylindrical manner to the
core as the lesions expand in diameter, forming a
v-shaped lesion in cross section. This criterion can be


used as a distinction between black rot and
Botryosphaeria rot.

Limb and twig infections begin as small, sunken,
oozing lesions, often red in color. The lesions
enlarge, exhibiting rings of black Pycnidia and loss of
bark.

Causal Organism

Botryosphaeria dothidea (anamorph Fusicoccum
aesculi) is the causal organism of Botryosphaeria rot.
Pycnidia, found on infected wood and fruit, are
typically compound and spherical (153 X 197pm).
Conidia are nonseptate and hyaline. Ascostroma are
solitary and scattered, botryose, ostiolate, and
spherical. Asci are cylindrical, eight-spored, and
bitunicate; ascospores are hyaline, one-celled, and
ovoid.

Disease Cycle and Epidemiology

Although ascospores and conidia are produced
throughout the growing season in the southeastern
United States, inoculum production is dependent on
temperature (optimum 82-900F) and number of
spores released is dependent upon the amount and
duration of rain. Infection by spores is most common
through wounds in fruit, twigs and limbs, although
twig and limb infection is often associated with the
periods of hot and dry weather.

Mycelium, pycnidia, and pseudothecia of B.
dothidea survive between seasons in cankers,
colonized dead bark, and mummified fruit. B.
dothidea can colonize in current-season mummified
fruit and fire blight strikes to provide a secondary
source of inoculum.

Management

Dead limbs, cankers and mummified fruit should
be pruned and removed from the orchard.
Current-season fire blight strikes should be removed
to lessen colonization of B. dothidea. Limb and
branch infections can also be reduced by irrigation
during hot, dry periods. Severity of Botryosphaeria
rot in the area and whether early-season latent
infections are common are the deciding factors for
chemical control timing. See Table 1.






2007 Florida Plant Disease Management Guide: Pear (Pyrus communis) 3


CERCOSPORA LEAF SPOT

Introduction

Cercospora leaf spot is a minor foliar disease of
apple which may cause early defoliation.

Symptoms

Lesions on infected leaves are round to oblong,
often with a zonate appearance.

Causal Organism

Pseudocercopsora mali is the causal organism of
cercospora leaf spot. Produced in clusters,
conidiophores are dark in color, sparingly branched
and septate. Conidia are typically hyaline, long and
slender and septate.

Management

Fallen infected leaves should be removed from
the area and destroyed.

CROWN GALL

Introduction

Crown gall affects woody and herbaceous plants
from over 90 families, including pears grown for fruit
production and ornamental use. Crown gall is
variable in severity but gradually lowers tree vigor
and may lead to tree death.


to as a tumor-inducing (Ti) plasmid, is carried by A.
tumefaciens.

Disease Cycle and Epidemiology:

Wounds are essential to the infection process and
initiation of the disease cycle. A. tumefaciens enters
through a wound, attaches to a susceptible plant cell
and inserts transfer DNA (T-DNA) from the Ti
plasmid into the plant cell chromosome. Expression
of the T-DNA results in overproduction of plant
hormones, stimulating plant cells to divide, enlarge
and form a gall. The pathogen may move from galls
to surrounding roots and soil, then disseminate to new
plants or planting sites by rain, irrigation water, wind,
insects, tools, and plant parts used for propagation.

Management

Good cultural and sanitation practices are key
deterrents to crown gall. These include choosing a
rootstock with low susceptibility, budding rather than
grafting, developing management practices that
minimize wounding, removing young infected trees
as well as older galled trees, and dipping shears in
rubbing alcohol for 10-15 seconds between cuts.
Planting sites where galled plants were grown should
be left fallow for several years. Effectiveness of
chemical control through soil fumigation and
rootstock dipping varies.

FIRE BLIGHT


Symptoms Introduction


Galls, varying in size, form on the crown, roots,
trunk or limbs. The texture of a gall can range from
soft and spongy to hard, depending on the amount of
vascular tissue it contains. Careful diagnosis of
smaller galls is important, as they may be confused
with excessive callus growth around wound sites, or
with nematode or insect induced galls.

Causal Organism

Agrobacterium tumefaciens is the causal
organism of crown gall. It lacks endospores, is
rod-shaped, gram-negative bacteria, aerobic and
motile by one to six flagella. A large
extrachromosomal piece of DNA, commonly referred


Fire blight is one of the most devastating
bacterial diseases affecting pear, apple, and other
rosaceous plants. This disease varies in severity from
year to year, dependent upon temperature and
precipitation. Additionally, fire blighted wood can
provide a suitable site for other diseases such as black
rot and white rot.

Symptoms

Plant parts affected by fire blight appear
scorched by fire. Infected blossoms may exhibit
ooze, and then change color from red to brown to
black as the disease progresses. Infected leaves will
turn brown to black and desiccate, yet remain
attached to the branches. Vegetative shoots often wilt






2007 Florida Plant Disease Management Guide: Pear (Pyrus communis) 4


and take on the shape of a shepherd's crook (Figure
2), the pith of infected stems exhibiting a dark brown
discoloration. The outer bark of infected branches
and limbs are often sunken and darker than normal,
whereas the inner tissues will be water-soaked with
reddish streaks while the pathogen is active, later
turning brown.


Figure 2. Fire blight of apple. Note blighted leaves and
shepherd's crook symptoms. Credits: Plant Disease Clinic,
Iowa State University

Fruit infected during the early season remain
attached to the cluster base, yet remain small and
appear shriveled and dark, whereas fruit infected as
the disease progresses from the branches appear less
shriveled and dark. Fruit infected following injury
often develop red, brown or black lesions, and may
exude an ooze which first appears clear or milky,
later turning red to brown.

Causal Organism

Erwinia amylovora is the causal organism of fire
blight. The rod-shaped bacterium is gram-negative
and facultatively anaerobic. Isolation and tentative
identification can be made using several selective or
differential media; rigorous identification requires
additional biochemical and molecular testing.


Disease Cycle and Epidemiology

E. amylovora overwinters in small twig cankers
and dead wood to provide an initial source of
inoculum early in the next season. Transferred by
rain or insects, the bacterium penetrates host tissue at
wounds or natural openings. Inoculum produced as
ooze from fresh infections can serve as a secondary
source of disease for later-season vegetative shoots,
blossoms and fruits. Lesion extension slows in late
summer to autumn in response to less favorable
conditions.

Severity of fire blight varies from season to
season, dependent upon the interaction of a
susceptible plant, a virulent pathogen, and favorable
weather conditions. Plant susceptibility varies with
plant age, phonological stage and horticultural
practices employed; strains ofE. amylovora vary in
virulence toward plant genotypes. Weather
conditions, particularly temperature and moisture,
affect vector activity (primarily bees) and pathogen
growth.

Management

Overwintering cankers should be removed
during the dormant season. Active lesions should be
pruned out at least 6-8 inches below obvious
discoloration. Pruning tools must be disinfected
between cuts to reduce spread of the bacterium.
Susceptible cultivars and rootstocks should be
avoided, as should the use of nitrogen fertilizers early
in the season and late-summer cultivation. There are
forecasting models available to time chemical
applications. Properly timed chemical applications
can be highly effective against fire blight. See Table
1.

FLY SPECK

Introduction

Flyspeck is a common disease of pear that
lowers fruit quality by fungal growth on the fruit
surface. Due to the warm, moist weather, fungicide
use is essential in the southeastern United States.






2007 Florida Plant Disease Management Guide: Pear (Pyrus communis) 5


Symptoms

Flyspeck colonies on fruit surfaces are
well-defined groupings of shiny, black, superficial
pseudothecia. Colony size varies from 1-3 cm and
round to irregular. Conidiophores and conidia are
produced within the colonies of pseudothecia during
warm, moist weather.

Causal Organism

Schizothyrium pomi (formerly Microthyriella
rubi; anamorph Z2'goplhitja jamaicensis) is the causal
organism of flyspeck. Pseudothecia vary in size and
have irregular margins. Embedded in a centrum
tissue asci are spherical to oval and bitunicate, each
ascus containing eight hyaline, two-celled ascospores.
The upper cells of ascospores are shorter and wider
than the basal cells. Conidiophores consist of a
subhyaline basal cell; a smooth, thick-walled brown
sector; an angular, subhyaline terminal cell; and two
hyaline conidiogenous cells. Two-celled conidia are
thin-walled and elliptical to obovate.

Disease Cycle and Epidemiology

S. pomi overwinters as pseudothecia on infected
twigs and woody reservoir hosts. Airborne
ascospores are released by the pseudothecia just prior
to bloom and germinate from 60.80F to 82.40F.
Under optimum conditions (63.10F, relative
humidity above 96%) conidia may be produced in
10-12 days. Airborne conidia are released after
sunrise as the relative humidity declines and the twigs
dry, providing the secondary inoculum.

Management

During normal to dry weather, well-pruned trees
will usually have less disease; during wet seasons
well-pruned and poorly pruned trees may be equally
diseased. Proper thinning of fruit can lessen the
microclimate for disease development that tightly
clustered fruit provides and allows for thorough
coverage of fungicide sprays. Primary control of
flyspeck is through fungicide sprays. See Table 1.


LEAF SPOT

Introduction

Various fungi cause leaf spot on pear. Due to the
warm, wet summers, leaf spot is more prevalent in
the southeastern United States.

Symptoms

Leaf spots vary in size, shape, and color,
depending on the pathogen involved (Figure 3).
Severely infected leaves will often turn yellow and
abscise. Severe defoliation can reduce tree vigor and
yield.


Figure 3. Leaf spot on apple leaf. Credits: D.M. Gadoury,
Dept. Plant Pathology, Cornell University, Geneva

Causal Organism

Various fungi.

Disease Cycle and Epidemiology

The fungal pathogens for leaf spot overwinter in
infected leaves, and twig cankers. In the spring
spores are released and spread by rain or overhead
irrigation. Secondary infections occur during warm,
wet weather.

Management

Infected leaves should be removed from beneath
the trees and buried or destroyed. Adequate spacing
of trees and reduction of overhead irrigation can
reduce infection. Control of primary inoculum
improves productivity of fungicide applications. See
Table 1.






2007 Florida Plant Disease Management Guide: Pear (Pyrus communis) 6


MUSHROOM ROOT ROT

Introduction

Mushroom root rot is also known as Armillaria
root rot, oak root fungus disease, and shoestring root
rot.

Symptoms

Foliage may turn yellow, then brown and dry
rapidly. Dark brown to black rhizomorphs, or
"shoestrings" appear at the soil line around the
trunk of the tree. A creamy white layer of fungus is
often present between the bark and the wood; a white
to light yellow mycelial growth within the bark of
surface roots. Honey-colored mushrooms may form
in groups around the drip line of the tree or next to
the trunk during moist periods.

Causal Organism

Armillaria tabescens is the causal organism of
mushroom root rot. Lacking an annulus on the stipe
of the mushroom (basidiocarp), it is easily
distinguished from other Armillaria species.
Blackish, hardened, mycelial extrusions are produced
on the bark of infected roots.

Disease Cycle and Epidemiology

In recently-cleared woodland (particularly that
which had oak cover), rhizomorphs and mycelial
strands of the fungus can remain on infected roots in
the soil for many years, serving as an initial source of
inoculum for new orchard trees. Rhizomorphs also
spread between trees, attaching to the roots of a new
host and entering through pressure and enzymatic
activity.

Management

Location of orchard plantings is important. New
trees should not be planted in recently cleared
woodland (particularly that which had oak cover),
near existing stumps or buried debris, or where trees
have recently died from mushroom root rot, unless
the root system has been removed in its entirety and
several years of fallow have passed. Fumigation of
the soil can assist in control of mushroom root rot.


PINK LIMB BLIGHT

Symptoms

Pink limb blight produces a pale pink mycelium
which often encircles limbs, twigs and trunks of trees.
The foliage distal from the affected area wilts and
dies, eventually killing the limb or twig.

Causal Organism

Erythricium salmonicolor (anamorph Necator
decretus)

Management

Infected tissue should be removed immediately;
pruning limbs a minimum of 4-6 inches below the
external appearance of mycelium on twigs. Prunings
should be collected and destroyed.

POWDERY MILDEW

Introduction

A persistent disease, the severity of powdery
mildew and resulting economic loss varies with
environmental conditions, cultivar susceptibility, and
management practices. Powdery mildew can be
especially damaging in nursery production.

Symptoms

Infections on leaves first appear on the lower
surface as grayish-white patches of mycelium and
spores (Figure 4) with chlorotic spots on the upper
surface. Infections may spread to the upper surfaces,
covering the entire leaf and eventually turning brown.
Leaves infected along the margin may curl, while
severely infected leaves may fold longitudinally,
become brittle and abscise.

Infected flower buds will open 5-8 days later
than healthy buds and exhibit reduced fruit set; flower
petals will be distorted and pale yellow or light green.
Pears affected during bloom may be covered by
white mycelium until early summer when the
mycelium sloughs off, leaving a russeted patch on the
surface where cells died.






2007 Florida Plant Disease Management Guide: Pear (Pyrus communis) 7


Figure 4. Powdery Mildew asexual stage on apple leaf.
Credits: Sherm Thompson,Utah State University

Causal Organism

Podosphaera leucotricha (anamorph Oidium
farinosum) is the causal organism of powdery
mildew on pear. Produced in long chains on thin,
amphigenous mycelium, conidia are ellipsoidal,
truncate, hyaline, and contain fibrosin bodies.
Perithecia are densely gregarious and subglobulose,
with apical and basal appendages. Apical appendages
are three to seven times longer than the diameter of
the perithecium, brown basally and widely spreading
or erect-fasticulate. Rudimentary basal appendages
are pale brown, short-tortuous, and simple or
irregularly branched. Asci are oblong to
subglobulose and contain 8 ovate to elliptical
ascospores.

Disease Cycle and Epidemiology

P. leucotricha overwinters as mycelium in
dormant buds infected during the previous growing
season. Conidia produced on the mycelium serve as
primary inoculum. Healthy buds often open earlier
than infected buds, thus providing susceptible tissue
upon conidia development. Limited germination
occurs at high temperatures or in free water. High
concentrations of spores are released in the air from
midday to early afternoon. Infection of young or
mechanically damaged leaves, blossoms and fruit
serve as a secondary source of inoculum.

Management

Dormant season pruning may remove infected
buds and reduce the level of primary inoculum.
During the growing season severely infected shoots
should be pruned and destroyed. Prevention of new


spores and reduction of spores produced on new
lesions may be accomplished through fungicide
sprays. See Table 1.

RUST

Introduction

Several related rust fungi infect pear in the
southeastern United States, including quince rust and
American hawthorn rust. These fungi involve two
host plants in their life cycle, usually requiring a
Juniperus species as an alternate host. The various
fungi differ in life cycle complexity and whether they
affect fruit, leaves, or both.

Symptoms:

Quince rust appears initially as yellow lesions on
the upper leaf surface (Figure 5). Lesions may later
appear on the lower leaf surface. Darker lesions may
appear on the calyx end of fruit, causing the fruit to
distort.


Figure 5. Juniper-pear rust on pear leaves. Credits: Andrej
Knuca, National Flrest Centre, Slovakia. Clemson
University USDA Cooperative Externsion Slide
Series.The Bugwood Network, NSF Center for Integrated
Pest Management and the University of Georgia

American hawthorn rust infects pear leaves, but
rarely infects fruit.

Causal Organism

Various Gymnosporangium species are the
causal organisms of rust on pear. Morphologies of
fungal structures vary between species.






2007 Florida Plant Disease Management Guide: Pear (Pyrus communis) 8


Disease Cycle and Epidemiology

On native cedars Gymnosporangium sp. will
induce a gall, from which telial horns will emerge
under wet conditions. During rains telia swell and
appear jellylike, releasing teliospores which then
germinate to produce basidiospores. Basidiospores
are immediately discharged into the air and can travel
more than 1 mile on air currents. Those landing on
susceptible apple tissue may germinate and infect the
host if a film of water is present for a suitable length
of time. Aeciospores are later released from aecia
during dry weather and may germinate and infect
native cedars.

Management

Removal of infected native cedars within close
proximity may reduce infection pressure, however,
elimination is unlikely as basidiospores can travel
great distances. Rust is best controlled using
fungicides. See Table 1.

SOOTY BLOTCH

Introduction

Sooty blotch is a late-summer disease of pear
that lowers fruit quality by fungal growth on the fruit
surface. Due to the warm, moist weather, fungicide
use is essential in the southeastern United States.

Symptoms

Sooty blotch colonies appear as olive green,
soot-like smudges on mature fruit. Large portions of
the fruit surface may be covered by colonies due to
secondary spread on the fruit.

Causal Organism

Gloeodes pomigena is the causal organism of
sooty blotch. Produced in the thallus, pycnidia are
dark brown, scattered or aggregate, and dimidiate.
Conidia are variable in length, generally
cigar-shaped, with slight constrictions at the point of
septation. Spores in mass are cream to pinkish in
color.


Disease Cycle and Epidemiology

Sooty blotch survives between seasons as
mycelium and pycnidia on infected twigs of apple
and reservoir hosts (woody plants common to
hedgerows and woodlots). Spores are released during
spring and early summer rains. Infection can occur
any time, but is most noticeable during late season.
Mycelial growth is possible despite a lack of free
water at relative humidities above 90%.

Management

During normal to dry weather, well-pruned trees
will usually have less disease. During wet seasons
well-pruned and poorly pruned trees may be equally
diseased. Proper thinning of fruit lessens the
microclimate for disease development that tightly
clustered fruit provides and allows for thorough
coverage of fungicide sprays. Primary control of
sooty blotch is through fungicide sprays. See Table 1.

SOUTHERN BLIGHT

Introduction

Southern blight occurs in orchards and nurseries
on trees approximately 3 years old and younger. Due
in part to the warm, humid weather, tree losses in
some southeastern United States have reached 30%
due to this disease.

Symptoms

A coarse, white mycelial mat is often found at
the base of an infected tree, progressing upward.
Small, white sclerotia develop within the mycelium,
later turning tan to brown. Leaves of an infected tree
may exhibit a reddish or grayish purple discoloration,
later drying and turning brown as the fungus girdles
the crown and the tree dies.

Causal Organism

Sclerotium rolfsii is the causal organism of
southern blight. Grown on a wide range of media,
the fungus produces white mycelium and reddish
brown to dark brown or tan, hard, round sclerotia. No
asexual spores are produced.






2007 Florida Plant Disease Management Guide: Pear (Pyrus communis) 9


Disease Cycle and Epidemiology

Sclerotia are easily dislodged from mycelium
and fall into soil, where they can survive for several
years. Infection occurs directly through both injured
and healthy bark. Warm summer temperatures
(77-950F), high soil moisture, good soil aeration and
plentiful organic debris promote a high incidence of
disease.

Management

Delay placement of apple trees where legumes or
solanaceous crops have been grown until the area has
been deep-plowed, fallowed for a season, and
fumigated.

INFORMATION SOURCES

Simone, G. W. and R.S. Mullin. 1999-2000
Florida Plant Disease Management Guide. Vol.
3: Fruit and Vegetables

Compendium of Apple and Pear Diseaes. 1990.
American Phytopathological Society.

CDMS Chem Search.
http://premier.cdms.net/webapls. Accessed
December 11, 2006.







2007 Florida Plant Disease Management Guide: Pear (Pyrus communis) 10


Table 1. Fungicides approved for disease management of Pear in Florida.


Chemical (a.i.) Fungicide Max ratelacre Min. days Disease Remarks 2
Group Application Season to harvest


Pristine 7 14.5-18.5 oz 74 oz 0 Black rot, Flyspeck,
(boscalid + Powdery mildew,
pyraclostrobin) Sooty blotch, Rust,
White rot

Basic Copper 53, M1 0.5 Ib per Fireblight Excessive doses
Cuprofix Disperss 100 gal may cause fruit
(basic copper sulfate) russet

Kocide 101, Champion M1 1 Ib 1 Fireblight Excessive doses
WP, Nu Cop 50WP may cause fruit
(copper hydroxide) russet


Kocide 2000, Kocide M1 0.75-1 Ib 1 Fireblight Excessive doses
DF, Nu Cop 50DF may cause fruit
(copper hydroxide) russet

Kocide 4.5LF, Champ M1 0.6-1.3 pt 1 Fireblight Excessive doses
Formula 2F, Nu Cop 3L may cause fruit
(copper hydroxide) russet

Dithane DF Rainshield, M2 3-6.4 Ib 21-25.6 Ib 77 Fireblight,
Manzate 75DF, Flyspeck, Leaf
Penncozeb 75DF spot, Rusts, Sooty
(mancozeb) blotch

Dithane F45 M2 2.4-4.8 pt 16.8-19.2 pt 77 Fireblight, Leaf
Rainshield, Manzate spot, Rusts
Flowable
(mancozeb)

Dithane M45, Manzate M2 3-6 Ib 21-24 Ib 77 Fireblight,
Pro-Stick, Penncozeb Flyspeck, Leaf
80WP (mancozeb) spot, Rusts, Sooty
blotch
Agri-Mycin 17, 25 24-48 oz 30 Fireblight
Streptrol
(streptomycin)
Dusting Sulfur, M1 rate varies Powdery mildew Do not use within 2
Kumulus DF, see labels weeks of an oil
Micronized Gold, spray treatment
Micrthiol Disperss,
Sulfur 90W
(sulfur)
Thiophanate Methyl 1 0.8 Ib 3.2 Ib 1 Flyspeck, Leaf
85WDG spot, Powdery
(thiophanate methyl) mildew, Sooty
blotch







2007 Florida Plant Disease Management Guide: Pear (Pyrus communis) 11


Table 1. Fungicides approved for disease management of Pear in Florida.


Chemical (a.i.) Fungicide Max ratelacre Min. days Disease Remarks 2
Group Application Season to harvest


Topsin M 70WP, 1 1 Ib 4 Ib 1 Flyspeck, Leaf
Topsin M WSB spot, Powdery
(thiophanate methyl) mildew, Sooty
blotch
Ziram 76DF, Ziram M2 6-8 Ib 56 Ib 14 Flyspeck, Leaf
Granuflo spot, Rust, Sooty
(ziram) blotch
1 Fungicide group (FRAC code): Numbers (1-37) and letters (M, U, P) are used to distinguish the fungicide mode of action
groups. All fungicides within the same group (with same number or letter) indicate same active ingredient or similar mode of
action. This information must be considered for the fungicide resistance management decisions. M = Multi site inhibitors,
fungicide resistance risk is low; U = Recent molecules with unknown mode of action; P = host plant defense inducers. Source:
http://www.frac.info/ (FRAC = Fungicide Resistance Action Committee).
2 Information provided in this table applies only to Florida. Be sure to read a current product label before applying any chemical.
The use of brand names and any mention or listing of commercial products or services in the publication does not imply
endorsement by the University of Florida Cooperative Extension Service nor discrimination against similar products or services
not mentioned.




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Last updated October 10, 2010 - - mvs