Euphorbia Pulcherrima Sau Poinsettia Pulcherrima (2)

8/16/2019 Euphorbia Pulcherrima Sau Poinsettia Pulcherrima (2)

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History of the Poinsettia

The poinsettia, Euphorbia pulcherrima Willd., is a member of the family Euphorbiaceae. The

genusEuphorbia contains some 700 to 1,000 species. It is characteried by a single female flo!er, !ithout

petals and usually !ithout sepals, surrounded by indi"idual male flo!ers all enclosed in a cup#shaped

structure called a cyathium. The sho!y red, pin$, !hite, or bicolored portion of the plant, popularly referred

to as the flo!er, consists of modified lea"es or bracts %&ig. 1'.

The poinsettia is a nati"e plant of (e)ico and originated in a rather limited region near present day Ta)co.

*ong before the arri"al of Europeans, the +tecs of central (e)ico culti"ated the plant and called it

uetla)ochitl. -ecause of its brilliant color, the poinsettia !as a symbol of purity to the Indians. It !as highly

pried by both ing /etahualcoyotl and (onteuma, but because of the high altitude climate, the plant

could not be gro!n in their capital, no! $no!n as (e)ico ity. The Indians used poinsettia bracts to ma$e a

reddish#purple dye. They also made a medicine for fe"er from the plants late).

uring the 17th entury, a group of &ranciscan priests settled near Ta)co. They began to use the poinsettia

in the &iesta of 2anta Pesebre, a nati"e procession. 3uan -alme, a botanist of the same period, mentionedthe poinsettia plant in his !ritings. He described it as ha"ing large green lea"es and a small flo!er

surrounded by bracts, almost as if for protection. The bracts, he said, turned a brilliant red. -alme also

found the plant flourishing on the slopes and in the "alleys near uerna"aca.

&ig. 4. 3oel 5oberts Poinsett

%1776#181' %clic$ image

forlarger "ie!'.

Poinsettias !ere first introduced in the 9nited 2tates in 148 by 3oel 5oberts Poinsett %40,4:' %&ig. 4'.While ser"ing as the first 9nited 2tates +mbassador to (e)ico, he "isited Ta)co and found the flo!ers

gro!ing on the ad;acent hillsides. Poinsett, a botanist of great ability, had some plants sent to his home in


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&ig. >. 2eedling culti"ar @=a$ *eaf, the

progenitor of modern poinsettia culti"ars

%clic$ image for larger "ie!'.

&ig. :. &ield production of poinsettia stoc$

plants in 2outhern alifornia in the mid#

16>0s %clic$ image for larger "ie!'.

uring the middle 1680s, poinsettia breeding programs !ere initiated at se"eral institutions, including the

Pennsyl"ania 2tate 9ni"ersity, the 9ni"ersity of (aryland, the 92+ 5esearch enter at -elts"ille,

(aryland, and by a number of commercial horticulture firms including +alealand in *incoln, /ebras$aA Paul

Ec$e 5anch in Encinitas, alifornia %&ig. :'A (i$$elsens in +shtabula, =hioA Earl 3. 2mall of Pinnellas Par$,

&loridaA Boder -rothers in -arberton, =hioA Cieger -rothers in Hamburg,


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&ig. 8. Paul (i$$elsen poinsettia %clic$

image for larger "ie!'.

&ig. ?. Winter 5ose the first culti"ar

!ith incur"ed bracts and foliage %clic$image for larger "ie!'.

In 16 Ec$espointG *ilo !as introduced. This !as the of the first dar$ leaf poinsettia culti"ars that !ere

early flo!ering, reco"ered uic$ly after unslee"ing, and had e)cellent foliage retention for the consumer.

This culti"ar reuired certain cultural techniues to insure good branching. In 1664, Ec$espointG

&reedom !as introduced. Ec$espointG &reedom contained the best characteristics of Ec$espointG *ilo

!hile branching more consistently for the producers. Today there are o"er 100 poinsettia culti"ars gro!n

commercially, !ith one culti"ar, Ec$espointG &reedom representing o"er 80 of the red mar$et

!orld!ide and 70#78 of that mar$et consisting of poinsettias !ith red bracts. =ne final re"olution to

poinsettia culti"ars !as the introduction of Ec$espointG Winter 5ose ar$ 5ed in 166 %&ig. ?'. This

culti"ar !as the first introduction in the JcurlyK family !ith dar$ red incur"ed bracts and deep dar$ greenincur"ed foliage. %+dapted from Ec$e, et al., 1660. The Poinsettia Manual L40M.'

Today, poinsettias may be found in many different colors %&ig. 7' as !ell as product forms from mini

poinsettias to large specimen trees and e"ery sie in bet!een. Testifying to its success and popularity, the

poinsettia is not only the most popular holiday flo!er, it is the number one flo!ering potted plant in the

9nited 2tates, !ith o"er ?8 million plants sold nation!ide in 4000 %?1'.


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&ig. 7. Plum Pudding, the first poinsettia

!ith purple bracts %clic$ image for larger

"ie!'.

iseases

2e"eral diseases affect production of poinsettia, including foliar diseases such as -otrytis gray mold,po!dery milde!, +lternaria blight, Nanthomonas blight, Er!inia blight, Phytophthora blight, and root

diseases such as Pythium, Phytophthora and 5hioctonia root rot. Po!dery milde! is a fairly recent

disease problem in poinsettia production that can de"elop e)plosi"ely late in the crop production cycle.

2cab caused by Sphaceloma poinsettiae, normally a disease problem only in states li$e &lorida and Ha!aii

!ith subtropical climates, has been introduced nation!ide the past couple of seasons !ith infected rooted

cuttings from propagators in entral +merica. =n the other hand, blac$ root rot caused by Thielaviopsis

basicola, a soilborne pathogen, !as a serious disease of poinsettia in the 1680s and early ?0s until the

floriculture industry mo"ed to soilless potting mi)es. 2ince the 1640s poinsettias in the industry ha"e

e)hibited a free#branching morphotype so that culti"ars de"elop multiple branches from a single pinch

resulting in many blooms. 5ecently, a phytoplasma etiology !as described that e)plained the free branching

habit %:7,:'.

&oliar iseases

Gray mold. Botrytis cinerea %teleomorph Botryotinia fuckeliana %de -ary' Whet.' can cause bro!n spots to

form on poinsettia flo!er bracts %&ig. ' and lea"es. The bract damage is easily confused !ith bract burn

%&ig. 6' caused by calcium deficiency, an imbalance among potassium, calcium, and magnesium or by an

ammonium#calcium antagonism. The fungus readily in"ades tissue damaged in any !ay, including that

caused by bract burn. +fter the true flo!ers ha"e fully de"eloped, Botrytisattac$s and co"ers them !ith the

typical smo$y, gray spores. Poinsettias are particularly susceptible to gray mold late in the season !hen it

can cause significant damage to the aesthetic uality of plants.


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&ig. . -ro!n spots on poinsettia

bracts caused by Botrytis %clic$


&ig. 6. -ract burn due to calcium deficiency


&ig. 10. 2tem

can$ers caused

by Botrytisinfection

%clic$ image for larger

"ie!'.

Botrytis cinerea produces massi"e numbers of spores that are readily detached by air mo"ement or rapid

changes in relati"e humidity !ithin the crop %>6'. epending upon the plant infected, 10: to 107

sporesOcm4 ha"e been obser"ed on leaf tissue %>7'. Pea$ spore concentrations in greenhouses can occur

at midmorning and midafternoon %>>,>:'. 2pores can also be dispersed by splashing %:0', in addition to

!ind dispersal. 2prin$ler irrigation splashes spores from place to place and pro"ides the moisture they need

in order to germinate and in"ade plant surfaces. +lthough Botrytis thri"es most under cool temperatures %40

to 48', it can in fact sur"i"e, sporulate, and continue to cause disease bet!een : and >0 %:1'.

It is important to manage Botrytis in the entire greenhouse because many different crops are susceptible to

gray mold %>7'. If geraniums, primulas, impatiens, or other highly susceptible crops are gro!n in the same

greenhouse as poinsettias, the fungus may form large numbers of spores on those "ery susceptible species

and spread to the poinsettias. In general, fading flo!er tissue of almost any crop becomes a food source

for Botrytis. In order to inhibit Botrytis de"elopment and minimie gray mold damage, the maintenance of

lo! relati"e humidity %belo! 6>' !ithin the crop canopy is crucial. Plants should be spaced and heating,

"enting, and air circulation regimes ad;usted to can $eep the humidity lo! throughout the poinsettiaproduction season. This usually means that pots must be separated once or t!ice during production so that

the canopy does not close. Irrigation systems that do not apply moisture to the abo"e ground portions of the


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plants help to maintain an en"ironment inhibitory to Botrytis gro!th. -y maintaining lo! humidity, the need

for fungicides is greatly reduced or eliminated. In operations !here humidity can be consistently minimied

!ithin the canopy, fungicides are not needed.

-ecause the fungus readily attac$s damaged, fading, or dead tissue, it is important to a"oid damaging

plants and, !hen possible, to remo"e damaged tissues. +ll plant debris should be promptly remo"ed fromthe greenhouse or disposed of in co"ered containers to pre"ent the spores formed on this material from

being dispersed to the crop. If these practices are follo!ed, then fungicides can help in management.

&ungicides including chlorothalonil, fenhe)amid, fludio)onil, and copper and copper plus mancoeb can be

used to protect foliage from Botrytis.


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fungicide treatments if and !hen they find the first colonies %1?,>8,>?'. Pre"enti"e treatments !hen the

pathogen is not present are purposeless and costly.

The most effecti"e fungicides for control of po!dery milde! on poinsettia appear to be the (Is

triadimefon, triflumiole, and myclobutanil %17'. The strobilurins $reso)im#methyl and trif lo)ystrobin are also

"ery effecti"e, as is piperalin %1,16'. + number of other materials pro"ide some disease suppression. 2incefungicides are a"ailable !hich gi"e e)cellent control of the disease, only po!dery milde! infestations that

are detected too late, after the disease has had numerous cycles of infection, !ould be e)pected to result in

significant crop loss.

Poinsettia scab. Poinsettia scab is a spot anthracnose disease caused by the fungus Sphaceloma

poinsettiae 3en$. D 5uehle %::,8?'. 9ntil recently, it had been $no!n to be a production problem only for

poinsettias in &lorida, !here inoculum presumably sur"i"es from year to year on landscape poinsettias. In

the past fe! years, poinsettia cuttings produced in entral +merica ha"e been the source of outbrea$s in

greenhouses across the 9nited 2tates. The host range for scab includes, in addition to Euphorbia

pulcherrima Willd. %poinsettia', t!o other euphorbs, E . heterophylla *. %(e)ican fire plant' and E.

prunifolia *. %painted euphorbia'. Weed species of Euphorbia are li$ely to be the source of spores foroccasional infections in ornamental stoc$ produced in subtropical and tropical +merica. &or the most part,

crop losses in /orth +merican production greenhouses ha"e been minor, but the economic impact has

been significant in a fe! cases.

&ig. 1>. 2cab lesions on a leaf. /ote

multiple lesions along top of midrib due to

channeling of spores in !ater %clic$ image

for larger "ie!'.

The disease affects both lea"es and stems of the plant %18'. 2mall, round lesions %1 to 8 mm in diameter'

form on the leaf blade, and commonly occur on the mid"ein or lateral "eins !here they freuently coalesce

%&ig. 1>'. The spots de"elop !hitish to bro!n centers, ha"e a dar$ red to purple rim, and often sho! a

diffuse yello! halo. The most distincti"e feature of the spots is that they are buc$led out from the upper leaf

surface. With time the leaf spots de"elop a coating of sporulation, causing them to change from !hite to a

"el"ety bro!n coloring %&ig. 1:'. The fungus ma$es single#celled, o"oid, hyaline conidia %> to 7 ) 1.8 to :

Qm' and also produces larger %7 to 48 ) 4.8 to 7 Qm', pigmented, 1 to 4 celled conidia, constricted at the

septation. The latter spore type, called the Jfa!cetti conidiumK has been thought to be the form most li$ely to

be in"ol"ed in long#distance spread of the fungus by !ind %&ig. 18'.


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&ig. 1:. 2porulating scab lesion on midrib

!ith "el"ety bro!n spores %clic$ image

for larger "ie!'.

&ig. 18. =ne to t!o#celled @fa!cetti conidia

of Sphaceloma poinsettiae %clic$ image

forlarger "ie!'.

&ig. 1?. 2cab stem lesions !ith red

pigmentation at margin %clic$ image

for larger "ie!'.

The stems of poinsettias sho! o"al to elongated raised can$ers, !ith dimensions of > to 10 ) 4 to ? mm.

The stem lesions are !hitish in color, and there may be red pigmentation around them %&ig. 1?'. =ne of the

most biarre features of the disease is the result of a gro!th regulating chemical produced by the fungus in

!hich a shoot !ith only a single can$er can sho! Jsuperelongation.K Thus, the internodes are lengthened

so that the shoot rises si) inches or more abo"e the rest of the crop %&ig. 17'. assa"a is affected by a

similar fungus, Sphaceloma manihoticola, and that pathogen has been sho!n to produce gibberellin +:%?4'.

E"en if the lesions on lea"es and stems are o"erloo$ed, gro!ers !ill notice the affected shoots that stretch

high abo"e the rest of the crop.


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&ig. 17. 2uperelongation of poinsettia

stems in the "egetati"e stage %left' and

later in the flo!er bract stage %right' due

to scab %clic$ image for larger "ie!'.

S. poinsettiae is fa"ored by high humidity and !et gro!ing conditions, !hich are not uncommon during

poinsettia propagation. 2plashing !ater !ill spread the spores easily, and insects might also mo"e spores

from plant to plant. etails of the epidemiology of S. poinsettiae ha"e not been determined.

ontrol studies by Engelhard in &lorida t!o decades ago sho!ed benomyl, chlorothalonil, mancoeb,

mancoeb plus thiophanate#methyl and copper hydro)ide to be effecti"e against poinsettia scab, !hereas

dicarbo)imides !ere ineffecti"e %48'. Trials conducted in 4001 by hase and aughtrey %1:' indicated that

triaoles, strobilurins, materials containing mancoeb, chlorothalonil, and a chlorothalonil plus thiophanate#

methyl combination !ere "ery effecti"e as protectants against poinsettia scab. -icarbonates and copper

sulfate pentahydrate !ere less effecti"e but pro"ided some control.

Poinsettia gro!ers are encouraged to scout for scab symptoms on lea"es and stems. If scab is detected,

infected plants should be remo"ed, and the remainder treated !ith an effecti"e fungicide. 2plashing during

irrigation and lengthy periods of leaf !etness should be a"oided in order to reduce the opportunity for ne!

scab infections.

&ig. 1. +lternaria leaf spot on poinsettia


Alternaria leaf spot and blight. +lternaria leaf spot in poinsettia %caused by Alternaria euphorbiicola' !as

first reported causing commercial losses from &lorida in about 16:. In 16?, Boshimura et al. %86'

described !hat appears to be the same disease caused by Alternaria euphorbiae%RMacrosporium

euphor biae'. The disease started in Ha!aii in late 16>. +lternaria blight of poinsettias is characteried by

small %less than 1 mm in diameter' lesions that are initially !ater#soa$ed. The roughly circular lesions turn

reddish#bro!n to dar$ bro!n and reach 40 mm in diameter %&ig. 1'. *esions may or may not ha"e a halo.*esions also form on bracts reaching :0 mm across !ith a blac$#purple margin. 2tem lesions can result in

girdling and subseuent loss of the stem. ulti"ar resistance !as e)amined in the 160s but no !or$ has

been done !ith the multitude of ne! culti"ars introduced since that time. Elimination of !ater on lea"es is

important to completely control +lternaria leaf spot of poinsettias. In 168, iprodione and the combination

product of thiophanate methyl and mancoeb !ere reported effecti"e in controlling +lternaria leaf spot %4?'.

+lthough both products are still a"ailable, (c


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cutting, causing disintegration %&ig. 16'. + characteristic rotten fishy odor often is present in the propagation

house !hen this disease is present. Infected cuttings parts that ha"e dried remain sources of acti"e

bacteria for at least ? !ee$s. Erinia carotovora is !idely distributed throughout most ornamental

production areas. It has e"en been found in irrigation !ater in some of the southern states.


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"ery high percentage of the crop can be lost. Pythium usually attac$s early in the season %>', soon after

cuttings ha"e been potted. 2e"erely affected rooted cuttings !ilt and die rapidly. The base of the cutting is

bro!n and has a !ater#soa$ed appearance. The callus and any ne! roots at the base of the cutting also

turn bro!n. The gro!th of infected plants that sur"i"e is stunted %&ig. 41' and these plants often !ilt %&ig.

44' during the heat of the day and reco"er at night later in the season. Infected roots of established plants

are dar$ bro!n in color and the outer layers of root tissue strip off lea"ing a bare strand of inner "asculartissue e)posed %&ig. 4>'. Infected plants that sur"i"e until flo!ering usually flo!er prematurely and defoliate.

&ig. 41. 2tunting of poinsettia gro!th %left'

due to Pythium root rot compared to

healthy plant %right' %clic$ image for larger

"ie!'.

&ig. 44. Wilted foliage of a poinsettia due to

Pythium root rot. Wilted plants may reco"er

at night %clic$ image for larger "ie!'.

&ig. 4>. 5oots of poinsettia !ith dar$

bro!n discoloration and sloughed off

cortical tissues %clic$ image for larger

"ie!'.

&ig. 4:. 2pherical oospores of

a Pythium sp. in the cortical cells of a

poinsettia root %clic$ image for larger "ie!'.

+n e)amination of the root corte) cells often re"eals the presence of spherical oospores %&ig. 4:'. Ho!e"er,

oospores may be absent and only sparse hyphae are obser"ed in the roots. When such roots are plated

onto !ater agar or a selecti"e medium %41,:>', Pythium gro!s out !ithin 4: hour Pythium irre"ulare and P.

ultimum are common species found in poinsettia roots %46,87' but a recent e)amination of isolates obtained

from clinic samples in Pennsyl"ania from 166? to 4001 indicated that Pythium aphanidermatumaccounted

for 7? of the Pythium root rot cases %(oorman, unpublished'. +t this time it is not $no!n !hether


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poinsettias are more susceptible to P. aphanidermatum than other species, !hether P. aphanidermatum is

infecting cuttings during propagation and is being inad"ertently shipped to other gro!ers or !hether the

greenhouse temperatures and other cultural conditions used in poinsettia production ma$e it more li$ely

that P. aphanidermatum !ill successfully attac$ poinsettias than other species.

Pythium inoculum may enter the production system from a number of sources. If the propagator of cuttingsallo!s Pythium to infect plants during the callusing and rooting process and infections go unobser"ed,

then Pythium#infected cuttings are sold to customers. =ther sources of the organism include contaminated

soil from under and bet!een benches or outside the greenhouse that is then mo"ed into pots or irrigation

!ater reser"oirs or onto benches or flood floors. If the gro!er uses contaminated field soil as a component

of the potting mi) or if the properly treated potting soil is contaminated !ith untreated soil, it is not unusual

for a "ery high percentage of the crop to be affected.


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Phytophthora root, crown, leaf, bract, and flower blight. T!o species of Phytophthora, P.

nicotianae -reda de Haan %RP. parasitica astur' and P. drechsleri ha"e been reco"ered from poinsettias in

greenhouses at "arious locations in the 9nited 2tates. 5oot, cro!n, and stem rot caused by P.

nicotianae !as first described by Engelhard and Ploet in 1676 %47', and foliar infection caused by both P.

nicotianae and P. drechsleri !as first described by Boshimura et al. in 168 %8'. Infected roots are bro!n

and depending on the en"ironmental conditions and the age of the plant, infection may be present for"arying lengths of time before !ilt or stunting is noticed. Infections at and abo"e the soil line are

characteried by purple#blac$ lesions that may e)pand rapidly from stems to brac$ petioles causing the

bracts to !ilt %&ig. 48'. *eaf lesions are paper#li$e and dry in te)ture, grayish bro!n at first, turning bro!n to

blac$. -light symptoms produced by these t!o species are "irtually identical %8'.

&ig. 48. Wilting of flo!er bracts and

foliage due to stem lesions caused by

aPhytophthora sp. %clic$ image for larger

"ie!'.

-oth P. nicotianae and P. drechsleri are heterothallic, reuiring +1 and +4 mating types to complete the

se)ual stage, and form thic$#!alled oospores %4'. 2ingle isolates readily produce sporangia on diseased

tissue and sporangia can uic$ly release s!imming oospores as the crop is !atered. 5ecent epidemics of

Phytophthora blight in floriculture production facilities throughout the 9.2. !ere caused by the spread of a

single clonal lineage %e.g., sporangia and oospores from a singlePhytophthora isolate' including one

epidemic in poinsettia caused by P. drechsleri %*amour and Hausbec$, unpublished '. (any poinsettia

production facilities utilie ebb and flood !atering strategies !hich pro"ide freuent opportunities for the

spread of sporangia and oospores to other plants as the crop is !atered. The incubation period bet!een

the initial infection of a plant and subseuent "isible symptoms pro"ides ample time for spread of inoculum

throughout a facility.

ontrol strategies that pre"ent initial infections are most effecti"e in limiting the de"elopment of

Phytophthora epidemics in poinsettia. These include the use of pathogen#free potting mi) and strict

sanitation in the production facility. The fungicides metala)yl %2ubdue' and more recently mefeno)am

%2ubdue (a))' ha"e been sho!n to be "ery effecti"e in controlling Phytophthora blight of poinsettia %8'.

Ho!e"er, isolates of P. nicotianae resistant to the highest rate of application of metala)yl or mefeno)am

ha"e been reported from floriculture production facilities %>0, *amour and Hausbec$, unpublished '. +pplying

fungicide to $no!n infected plants !ill increase the chance of selecting for insensiti"e isolates. The most

effecti"e !ay to halt an epidemic is to remo"e all plants from a production area in a facility that ha"e been

irrigated !ith !ater from the reser"oir that collects recycled !ater from $no!n infected plants. E"en healthy

loo$ing plants may be infected so strict sanitation follo!ing an epidemic is mandatory to pre"ent re#

occurrences.


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Rhizoctonia stem rot. 2tem rot caused by $hi%octonia solani uhn +


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&ig. 4. 5ooting strip remo"ed from

protecti"e plastic co"er to

re"eal $hi%octoniahyphae gro!ing through

strip %clic$ image forlarger "ie!'.

Rhizoctonia crown and root rot. 5oot rot may de"elop either in the rooting cube or on rooted cuttings

transplanted to pots as the crop is finished for retail. Infected roots become !ater#soa$ed then bro!n. -oth

root tips and sections of the root a!ay from the tip may de"elop symptoms. ro!n rot can de"elop on the

stem as lesions e)pand from stem infections occurring during propagation. Ho!e"er, stem lesions may

de"elop at a much slo!er pace on rooted plants, since this tissue is more hardened off and thus more

resistant than stems of ne!ly made cuttings. &oliar symptoms of cro!n and root rot include chlorosis, leaf

necrosis, !ilting, defoliation, and plant death, but often the most common symptom is stunting. 5oot rot

infections may be initiated from lesions on stems or from inoculum introduced to the potting mi) from debris

sur"i"ing in the greenhouse.


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onclusion

The long production season for poinsettias %from propagation in the hot months of summer to "egetati"e

gro!th and then flo!er bract de"elopment in the shorter days and cooler months of fall and early !inter'

pro"ides a !ide range of en"ironmental conditions that can foster a series of diseases. We ha"e described

the ma;or poinsettia diseases that are !idespread in the industry. + number of other less common diseases

can cause significant problems for indi"idual gro!ers !hen fa"orable en"ironmental conditions pre"ail. In

addition to biotic agents, improper fertiliation practices can cause symptoms in poinsettias. +

con"enient table summariing the management of poinsettia diseases and nutrient deficiencies is a"ailable

online from Penn 2tate 9ni"ersity. + description including images of physiological disorders in poinsettia

due to improper fertiliation can be found online from /orth arolina 2tate 9ni"ersity. Plant pathologists !ill

continue research and e)tension efforts to pro"ide gro!ers !ith the best possible disease management

strategies that !ill help to preser"e the poinsettia as the hristmas flo!er.

httpSOO!!!.apsnet.orgOpublicationsOapsnetfeaturesOpagesOpoinsettiaflo!er.asp)

Mai multe boli afectează producția de Poinsettia, inclusiv a bolilor foliare, cum ar mucegai Botrytis gri, fainarea, Alternaria pacoste, Xanthomonas pacoste,r!inia pacoste, Phytophthora mana, "i boli de rădăcină, cum ar Pythium,Phytophthora "i #hizoctonia $

%ăinarea este o problemă destul de recentă a producției Poinsettia care se poate

dezvolta e&ploziv t'rziu (n ciclul de producție a culturilor$ )rusta cauzată de*phaceloma poinsettiae, (n mod normal, o boală problemă numai (n state precum%lorida "i +a!aii cu climă subtropicală, a fost (nregistrată la nivel național (nultimele sezoane cu buta"i (nrădăcinați infectate de propagatori din America)entrală$

Pe de altă parte, putregaiul negru de rădăcină cauzat de hielaviopsis basicola-unagent patogen a fost o boală gravă la Poinsettia (n anii ./01 "i (nceputul anilor 21p'nă la industria 3oristică mutată la mi&urile de sol (n ghivece$ Av'nd (n vederecă această specie (n ./41, (n industrie a prezentat o liberă ramicare, astfel

(nc't să dezvolte soiuri multiple, ramuri dintr-un singur v'rf de cuțit care rezultă (n mai multe 3ori$

Mucegai gri$ Botrytis cinerea 5teleomorph Botryotinia fuc6eliana 5de Bary78hetz$7 Poate provoca pete maro, care se formează pe bracteele de 3oriPoinsettia 5%ig$ 97 "i frunze$ Pagubele asupra bracteelor sunt u"or de confundat cuarsura 5%ig$ /7 cauzate de decienta de calciu, un dezechilibru (ntre potasiu,calciu, magneziu sau de antibioză amoniu-calciu$ )iuperca invadează țesutul u"ordeteriorat (ntr-un fel anume, inclusiv cea cauzată de arsura bracteelor$ :upă ce s-au dezvoltat adevărate 3ori complete, Botrytisattac6s le acoperă cu tipice sporide fum, gri$ Poinsettias sunt deosebit de sensibile la mucegai gri (n sezonult'rziu c'nd aceasta poate provoca daune semnicative privind calitatea esteticăa plantelor$ :ezvoltare mucegaiului gri apare, de asemenea, (n timpultransportului, dacă culturilor au fost infestate (n sera de producție$ Mare, marodeschis p'nă la cafeniu, gangrenele u"or ad'ncite 5g$ .17, atunci c'nd prezintă

http://www.ppath.cas.psu.edu/extension/plant_disease/pdf%20Flowers/Poinsettia%20Diseases.pdfhttp://www.ppath.cas.psu.edu/extension/plant_disease/pdf%20Flowers/Poinsettia%20Diseases.pdfhttp://www.ces.ncsu.edu/depts/hort/poinsettia/corrective/a11.htmlhttp://www.ces.ncsu.edu/depts/hort/poinsettia/corrective/a11.htmlhttp://www.ces.ncsu.edu/depts/hort/poinsettia/corrective/a11.htmlhttp://www.apsnet.org/publications/apsnetfeatures/pages/poinsettiaflower.aspxhttp://www.ppath.cas.psu.edu/extension/plant_disease/pdf%20Flowers/Poinsettia%20Diseases.pdfhttp://www.ces.ncsu.edu/depts/hort/poinsettia/corrective/a11.htmlhttp://www.ces.ncsu.edu/depts/hort/poinsettia/corrective/a11.htmlhttp://www.apsnet.org/publications/apsnetfeatures/pages/poinsettiaflower.aspx


17/29

răni mai vechi sunt pe ramuri mari sau prin intermediul sucursalelor ramurilorbifurcate la capăt crăpate$

&ig. . -ro!n spots on poinsettia

bracts caused by Botrytis %clic$


&ig. 6. -ract burn due to calcium deficiency


Botrytis cinerea produce un număr masiv de spori, care sunt u"or de deta"at demi"carea aerului sau schimbări rapide (n umiditatea relativă (n cultură 5;/7$ spori ? cm4 pe țesut defrunză 5;>7$ )oncentrațiile de spori de v'rf (n sere pot apărea la mi@locul după-amiezii "i dimineții 5;;,;=7$ *porii pot , de asemenea, dispersați prin stropire5=17, (n plus față de v'nt$ rigare orin aspersiune sporesc sporii din loc (n loc "ioferă umiditatea de care au nevoie pentru a germina "i a invada suprafețeleplantei$ :e"i Botrytis prosperă mai mult la temperaturi reci 541 la 40 )7, poatesupraviețui "i continuă să provace boli chiar "i (ntre = "i ;1 ) 5=.7$


18/29

Poinsettia$ Fu numai că colonii albe strica frunzele 5g$ ..7, dar ciuperca formatcolonii albe dramatice pe bractee colorate, plante redare nevandabil 5%ig$ .47$

&ig. 11. olonies of po!dery milde! on a

leaf %clic$ image for larger "ie!'.

&ig. 14. olonies of po!dery milde! on

flo!er bracts %clic$ image for larger "ie!'.

Agentul patogen este un sp Eidium$ 5numai (n stadiul anamorf a fost observată7$

Fu are gazde cunoscute, altele dec't Poinsettia, ceea ce (nseamnă că, dacăcultivatorii ține poinsettias peste (n seră de la an la an, nu este de natură săsupraviețuiască dec't (n climate fără gheață (n cazul (n care poinsettias locuiescpe tot parcursul anului ca plante ornamentale peisa@$ Agentul patogen este mutatde la efect de seră cu efect de seră pe buta"i sau plante infectate$ Ericeactivitate cultivator (n cultura, cum ar spațierea, sau chiar pulverizare poatedispersa (n aer conidii 5.17$ oate soiurile de Poinsettia testate au arătatsensibilitate la boala 5.47$ *tudii de mediu la Michigan *tate Dniversity audemonstrat că făinare nu se va dezvolta (n timpul verii, din cauza efectelornocive ale temperaturi ridicate asupra procesului de infectie 59,/,.4,.;7$ Fumaiatunci c'nd temperaturile cu efect de seră (ncetează să a@ungă la 92 % 5;1 )7

(n timpul zilei va (ncepe făinare epidemia a obține un impuls$


19/29

in sere de producție din America de Ford au fost minore, dar impactul economic afost semnicativă (n c'teva cazuri$

&ig. 1>. 2cab lesions on a leaf. /ote

multiple lesions along top of midrib due to

channeling of spores in !ater %clic$ image

for larger "ie!'.

Boala afecteaza atat frunze "i tulpini de plante 5.07$ Jeziuni mici, rotunde 5de la .la 0 mm (n diametru7 formular pe lama frunze, "i frecvent apar pe midvein saulaterale venele (n cazul (n care se unesc (n mod frecvent 5%ig$ .;7$ *poturiledezvolta albicios la centrele de maro, au un ro"u (nchis la #M violet, "i arată demulte ori un halou galben difuză$ )aracteristica cea mai distinctivă a pete este căacestea sunt cedat de la suprafața frunzelor superioare$ )u timpul petele frunzedezvolta un strat de sporulare, care le determină să se schimbe de la alb la oculoare maro catifelat 5%ig$ .=7$ )iuperca face unicelular, ovoid, conidii hialin 5cu; la > & .$0 pentru a =Fm7 "i, de asemenea, produce mari 5> pentru a 40 & 4$0pm la > pm7, pigmentat, . p'nă la doi celula conidii, constr'nsă la septation$Dltimul tip de spori, numit Kfa!cetti conidiiK a fost considerat a forma cea maisusceptibile de a implicate (n răsp'ndirea pe distanțe lungi a ciupercii de v'nt5%ig$ .07$

&ig. 1:. 2porulating scab lesion on midrib

!ith "el"ety bro!n spores %clic$ image

for larger "ie!'.

&ig. 18. =ne to t!o#celled @fa!cetti conidia

of Sphaceloma poinsettiae %clic$ image

forlarger "ie!'.


20/29

&ig. 1?. 2cab stem lesions !ith red

pigmentation at margin %clic$ image

for larger "ie!'.

ulpinile de poinsettias arată ovale pentru can6ers ridicate alungite, cudimensiuni de ; p'nă la .1 & 4 la 2 mm$ Jeziunile stem sunt albicioasă culoare, si

nu pot de culoare ro"ie pigmentare @urul lor 5%ig$ .27$ Dna dintre caracteristicilecele mai bizare ale bolii este rezultatul unui produs chimic de reglare a cre"teriiprodusă de ciuperca (n care o trage cu un singur gangrenă poate arătaKsuperelongation$K Astfel, internodii sunt prelungite astfel (nc't trage ridică "aseinci sau mai sus de restul recoltei 5g$ .>7$ )assava este afectată de o ciupercasimilară, *phaceloma manihoticola, iar agentul patogen a fost demonstrat pentrua produce gibberellin A= 5247$ )hiar dacă leziunile pe frunze "i tulpini sunt trecutecu vederea, cultivatorii vor observa muguri afectate care se (ntind deasuprarestul culturii$

&ig. 17. 2uperelongation of poinsettia stems in the

"egetati"e stage %left' and later in the flo!er bract stage

%right' due to scab %clic$ image for larger "ie!'.

*$ poinsettiae este favorizat de umiditatea ridicată "i condițiile de cre"tereumede, care sunt mai puțin frecvente (n timpul nu Poinsettia propagare$ *tropiriicu apă se va răsp'ndi sporii u"or, "i insecte s-ar putea deplasa, de asemeneaspori de la planta la planta$ :etalii privind epidemiologia *$ poinsettiae nu au fostdeterminate$ *tudiile de control de ngelhard (n %lorida urmă cu două decenii auarătat benomil, clorotalonil, mancozeb, mancozeb plus tiofanat-metil "i hidro&id

de cupru pentru a ecient (mpotriva Poinsettia crustă, (n timp ce dicarbo&imideau fost ineciente 5407$ *tudiile realizate (n 411. de către )hase "i :aughtrey


21/29

5.=7 a indicat că triazoli, strobilurine, materialele care conțin mancozeb,clorotalonil, "i o clorotalonil plus tiofanat-metil combinație au fost foarte ecienteca protectori (mpotriva Poinsettia crustă$ Bicarbonați "i sulfat de cuprupentahidrat au fost mai puțin eciente, dar cu condiția anumit control$

)ultivatorii Poinsettia sunt (ncura@ate să *cout pentru simptome crustă pe frunze

"i tulpini$ :acă se detectează rapăn, plante infectate trebuie eliminate, iar restulse tratează cu o fungicid ecient$ *tropire (n timpul irigare "i perioade lungi defrunze umezeala ar trebui evitate pentru a reduce posibilitatea de infectii noicrustă$

&ig. 1. +lternaria leaf spot on poinsettia


Alternaria la fața locului frunze "i pacoste$ Alternaria la fața locului frunze (nPoinsettia 5cauzate de Alternaria euphorbiicola7 a fost prima raportat cauz'ndpierderi comerciale din %lorida (n ./9=$


22/29

dezintegrare 5%ig$ ./7$ Dn miros de pe"te putred caracteristic de multe ori esteprezent (n casa de propagare atunci c'nd această boală este prezent$ Buta"ipiese infectate care au uscate răm'n surse de bacterii active pentru cel puțin 2săptăm'ni$ r!inia carotovora este distribuit pe scară largă (n cele mai multezone de producție ornamentale$ Acesta a fost găsit chiar "i (n apă pentru irigații

(n unele state din sud$ )ultivatorii au raportat că tratamentul apei preventiv cu1,0 p'nă la . ppm brom sau clor a fost ecient$ Dtilizarea bactericide este rareoriutil cu boli moi putregai de buta"i$

&ig. 16. Er!inia blight on poinsettia cuttings

in propagation %clic$ image for larger "ie!'.

&ig. 40. +ngular leaf spots on poinsettia

caused by !anthomonas %clic$ image

forlarger "ie!'.

Ja fața locului frunze Xanthomonas$ Ja fața locului frunze Xanthomonas pepoinsettias a fost raportat inițial (n ./0. din ndia 50=7$ Mai t'rziu a fost descris cacauz'nd pierderi comerciale (n producția (n aer liber de poinsettias (n %lorida (n./21 5=/7$ )auza este Xanthomonas campestris pv$ poinsettiicola$ ndica pete

(ncepe gri mat (n zonele u"or (mbibată (n apă maro$ )a leziunile mature se (ntorc

galben p'nă la cafeniu "i sunt (mpră"tiate pe suprafața frunzelor$ Dneori, ei mări"i devin unghiulare (n formă, datorită circulație limitată peste vene frunze 5%ig417$ Aceasta boala poate confundată cu simptome timpurii ale ruginii$ nfecțiisevere poate provoca o denaturare a frunze noi, precum "i cloroza complet "i, (nnal e&tirpare de frunze mai mari$ Atunci cand boala a fost descoperit (n %lorida,cercetatorii au descoperit ca multe, dacă nu toate, soiuri populare de zi au foste&trem de sensibile la Xanthomonas la fața locului frunze$

Fici o lucrare nouă a fost efectuat pentru a evalua rezistenta soiul$ :e controltrebuie să se bazeze pe eliminarea tuturor plantelor de stoc cu Xanthomonas lafața locului frunze$


23/29

focar odată infecție a avut loc$ Boala este aproape imposibil de controlat, cue&cepția cazului plantele sunt produse fără udare sau e&punerea la precipitații$

Boli rădăcină

Pythium rădăcină putrezească$ %iecare sezon, unele cultivatorii Poinsettia (nt'lni

pierderi de recolte, ca urmare a Pythium rădăcină rot$


24/29

a Pythium sp. in the cortical cells of a

poinsettia root %clic$ image for larger "ie!'.

E e&aminare a celulelor corte&ului rădăcinii relevă adesea prezența oospores

sferice 5g$ 4=7$ )u toate acestea, poate absent oospores "i numai hife raresunt observate (n rădăcini$ Atunci c'nd astfel de rădăcini sunt placate pe agar cuapă sau un mediu selectiv 54.,=;7, Pythium cre"te (n termen de 4= irregularehourPythium "i P$ ultimum sunt specii comune găsite (n rădăcinile Poinsettia54/,0>7, dar o e&aminare recentă de izolate obținute din clinica probe dinPennsylvania de la .//2 la 411. a indicat că Pythium aphanidermatumaccountedpentru >2C din cazuri putrezirea radacinilor Pythium 5maur, nepublicat7$


25/29

eliminarea agentului patogen din sistemul de producție$ Microorganismepatogene amestecuri ghivece sunt esențiale (n acest efort "i a practicilorgenerale de salubritate (n seră ar trebui să vizeze eliminarea sau tratarea soluluicare pot sferei de Pythium$ :isinfesting suprafețe banc, sistemelor de plansee deinundații, banci ghivece, unelte "i echipamente care vor sa contactati amestecul

ghiveci este important$ :acă iaz sau @et de apă este folosită pentru irigații,conducta de admisie trebuie să e bine deasupra fundului, astfel (nc'tsedimentele să nu e absorbit (n$ :acă alimentarea cu apă este suspectat de a o sursă de Pythium, poate necesar pentru a trata apa 544 7$ *isteme de irigare

(n care apa neutilizat este reciclat, odată contaminate cu un agent patogen,devine o sursă continuă de Pythium$ :in acest motiv, BB "i sistemul de curgererezervoare trebuie acoperite pentru a preveni solului sau resturi contaminate dela introducerea lor$ Pentru a elimina resturile de plante, care pot port agentuluipatogen din apa, apa ar trebui să e trecut peste un ecran grosier (nainte de a revenit la rezervor$

ntr-o operație de seră cu o istorie de putrezirea radacinilor Pythium, fungicide sau

agenți de control biologic ar aplicat ca la (nceputul ciclului de trunchiere posibil$Agenții biologici, inclusiv specii "i tulpini de richoderma, Bacillus, Iliocladium, "i*treptomyces, pot aplicate pentru a se amesteca ghiveci (nainte, (n timpul sauimediat după transplant$ / 54>7, "i infecția foliare cauzată at't P$ nicotianae "iP$ drechsleri fost descrisă pentru prima dată de Loshimura "i colab$ (n ./90 5097$#ădăcini infectate sunt de culoare maro "i (n funcție de condițiile de mediu "iv'rsta plantei, infectie poate prezent pentru diferite lungimi de timp (nainte8ilt sau pipernicire se observă$ nfecții la "i deasupra liniei de sol secaracterizează prin leziuni violet-negru, care se poate e&tinde rapid din tulpini laBrac6 pețiolele cauzează bracteele sa se oleasca 5%ig$ 407$ Jeziunile frunze suntde h'rtie ca "i uscat (n te&tură, maro gri la prima, de cotitură maro la negru$*imptome pacoste produse de aceste două specii sunt practic identice 5097$


26/29

&ig. 48. Wilting of flo!er bracts and foliage due to stem

lesions caused by aPhytophthora sp. %clic$ image

for larger "ie!'.

At't P$ nicotianae "i P$ drechsleri sunt heterothallic, necesit'nd A. "i A4 tipurigenetice pentru a naliza etapa se&uală, "i formează oospores cu pereți gro"i5497$ zolate singure produc u"or sporangia asupra tesutului bolnave "i sporangiapoate elibera rapid zoospores (not, recolta este udata$ pidemii recente dePhytophthora pacoste (n facilități de producție pentru 3oristica pe intreg teritoriul*DA au fost cauzate de răsp'ndirea unui singur neam clonală 5de e&emplu, despori "i zoospores de la un izolat singlePhytophthora7, inclusiv o epidemie (nPoinsettia cauzate de P$ drechsleri 5Jamour "i +ausbec6, nepublicat7 $ Multeinstalații de producție Poinsettia utiliza BB "i udare de inundații strategii careoferă oportunități frecvente de răsp'ndire a sporangia "i zoospores la alte planteca recolta este udata$ Perioada de incubatie dintre infecția inițială a unei plante "i

simptome vizibile ulterioare prevede sucient timp pentru răsp'ndirea de inoculde-a lungul unei instalații$

*trategii de control care previn infectiile initiale sunt cele mai eciente (nlimitarea dezvoltării epidemii Phytophthora (n Poinsettia$ Acestea includ utilizareade agenți patogeni liber amestec ghivece "i canalizare strictă (n instalația deproducție$ %ungicide metala&il 5supune7 "i, mai recent mefeno&amului 5*upuneMa&&7 s-au dovedit a foarte ecient (n controlul Phytophthora mana dePoinsettia 5097$ )u toate acestea, izolate de P$ nicotianae rezistente la cea maimare rata de aplicare a metala&ilului sau mefeno&amului au fost raportate deinstalații de producție 3oricultură 5;1, Jamour "i +ausbec6, nepublicat7$ Aplicareafungicid pentru plantele infectate cunoscute va cre"te "ansa de a selecta pentruizolate insensibili$ )el mai ecient mod de a opri o epidemie este de a eliminatoate plantele de la o zonă de producție (ntr-o instalație, care au fost irigate cuapă din rezervorul care colecteaza apa reciclată de la plantele infectatecunoscute$ )hiar plante sanatoase cauta pot infectate de salubrizare at't destricte (n urma unei epidemii este obligatorie pentru a preveni re-evenimente$

#hizoctonia putregai stem$ *tem putregai cauzat de #hizoctonia solani Nuhn AI-=este cel mai important boala care afecteaza Poinsettia (n timpul propagării$Agentul patogen are o gamă foarte largă de gazdă, precum "i o capacitate maresaprote competitiv$ Această combinație de caracteristici oferă o oportunitateideală at't pentru infecția țesutului gazdă "i colonizarea resturi vegetale, urmată

de supravietuire ulterior pe termen lung, e ca miceliu sau sclerotia asociate curesturi de cultură$ )ultivatorii pot practica canalizare strictă dar de multe ori #$


27/29

solani devine un agent patogen indigene (n facilități de producție cu efect de serăca ciuperca supraviețuie"te (ntre culturi (n moloz infestate lăsat (n urmă pebanca, echipamente, eta@, pasarele, "i chiar "i (n crevase pe banci de lemn$

Poinsettia pot propagate (n benzi Penoplast (nrădăcinare .1 unități, cuburi vataminerala, sau blocat direct (ntr-un amestec soilless ghiveci (n ghivece$

Propagarea Poinsettia apare, de obicei, (n lunile calde de iulie "i august (n seră (ncondiții de umiditate frunze aproape constant de la sistemele de ceață conceputepentru a preveni tăierea de olirea$


28/29

&ig. 4. 5ooting strip remo"ed from

protecti"e plastic co"er to

re"eal $hi%octoniahyphae gro!ing through

strip %clic$ image forlarger "ie!'.

#hizoctonia coroană "i putrezirea radacinilor$ Putregai de rădăcină se pot dezvoltae (n cubul de (nrădăcinare sau pe buta"i (nrădăcinați transplantat la vase ca

recolta este terminat pentru retail$ #ădăcini infectate devin apoi maro (mbibat (napă$ At't sfaturi rădăcină "i secțiuni ale rădăcinii departe de v'rful poatedezvolta simptome$ )ro!n putregai se poate dezvolta pe tulpină ca leziunile see&tindă de la infectii stem care apar (n timpul de propagare$ )u toate acestea,leziunile stem poate dezvolta (ntr-un ritm mult mai lent pe plante (nrădăcinate,deoarece acest tesut este mai (ntărit oprit "i, astfel, mai rezistent dec't tulpini debuta"i nou făcute$ *imptome foliare de coroană "i putrezirea radacinilor includcloroză, necroză frunze, olire, defoliere, "i moartea plantelor, dar de multe oricel mai frecvent simptom este piticirea$ nfecții putregai rădăcină poate inițiatăde leziuni pe tulpini sau de la inoculare a prezentat la amestecul ghiveci deresturi supraviețuitor (n seră$ 7$ n general unul aplicarea fungicid estesucientă pentru a prote@a culturile timpul ciclului de propagare$ :eoarece unele


29/29

fungicide afecta numărul de rădăcini formate pe buta"i, cultivatorii ar trebui sătesteze fungicid specic de combinații cultivar pentru siguranță (nainte de autiliza un produs pe (ntreaga cultură 527$ :upă transplantare, fungicid Băuturilepot necesare la intervale regulate, pentru a preveni coroană "i putrezirearadacinilor$

Documents

Euphorbia Pulcherrima Sau Poinsettia Pulcherrima (2)