Algae and phanerogamic parasite

Description about algae and phanerogamic plant parasites which are also responsible for plant diseases, are described in easy and simple manner

1. ALGAE
AND
PHANEROGAMIC PARASITE
N.H. SHANKAR REDDY
2
ND
PH.D. PLANT PATHOLOGY
ANNAMALAI UNIVERSITY

2. Red rust of guava –Cephaleuros
parasiticus
Symptoms
•Diseasesymptomsareexhibitedonbothabaxialand
adaxialleafsurfacesasorange,rust-colored,densesilky
tuftsrangingfrom5to8mmindiameter.
•Thesespotsusuallycometogethertoformlargeirregular
patchesonaleaf.Asthespotsmaturetheytakeonadull,
grayishgreencolor.
Management
•Algalleafspotcanbereducedbymaintainingtreevigor
withculturaltechniquessuchasproperfertilizationand
irrigation,properpruningtoenhanceaircirculation
withinthecanopyandsunlightpenetration,managing
weedsandwidertreespacing.
•SprayCopperoxychloride0.25%.

3. Red rust of mango –Cephaleuros
virescnes
Symptoms
•Algaeattacksfoliageandyoungtwigs.
•Rustyspotsappearonleaves,initiallyascircular,
slightlyelevated,coalescetoformirregularspots.
•Thesporesmaturefalloffandleavecreamto
whitevalvettextureonthesurfaceoftheleaves
Management
•Bordeauxmixture(0.6%)orCopperoxychloride
0.25%

4. phanerogamic parasite
•Thepathogenicfloweringplants,alsocalledparasiticangiospermscanbeclassified
asrootparasitesorstemparasites.
•Rootparasites(witchweedandbroomrape)aremorecommonandmorediverse
taxonomically.
•Stemparasitesincludethedodder(Cuscuta)andmistletoes(Arceuthobium).

5. Cuscuta
Cuscutaisaslender,yellowthreadlike,andproducedwhite,
yellowishorpinkishcolourflowersandabsorbsnutrients
throughhaustoria.(herethecuscutaproducerudimentary
flowers)
oItbelongstothefamilyConvolvulaceae
Hosts-More than 100 species of cuscutaare attacking on
trees, the main hosts include, clover, onion, alfalfa, potatoes,
sugar beets and ornamental crops
Management
oUseofdodderfreeseeds
owithhostplantcanpreventfurtherspread.
oApplicationofcontactherbicides2,4-D,pentachlorophenol
oCroprotationfor4to5yearsshouldbeadopted.

6. Loranthus
Lorathusisapartialstemparasite,mainlyinfects
coniferousandforesttrees.Itproducewedgeshaped
haustoriaandcontinuouslysuckthenutrientsfromhost
oInSanskrititiscalledas“vrikshabhaksha”(planteater)
oItbelongstothefamilyLoranthaceae
Host-Fruit trees and forest trees
Management
•Handpickingofparasiteatearlystagesofitsgrowthor
cuttingandremovingoftheinfectedtrees.
•Injectionofcoppersulphateand2,4-Dintotheaffected
brancheshavebeenfoundeffective.

7. Orobanche
Orobancheisacompleterootparasiteaffectsherbaceousdicotyledonous
cropplants,showssymptomsofsmallpatches,yellowingofleavesand
stuntedgrowth
ItbelongstothefamilyOrobachaceae
Host–Sunflower,tobacco,tomato,brinjal,carrot,cabbage,lettuce,fava
bean,broadbeanandsunflower
Management
•Preventtheintroductionofseedsfromnewareasandavoidcultivationof
susceptiblecrops
•Useofresistantvarieties
•Sprayingthesoilwith25%coppersulphatesolutionfoundtobe
successful.

8. Striga
Strigaisapartialrootparasitewhichparasiterootsofthehost,contains
greenslightlyhairystemandleaves,doesn’tgrowbeyond30cmhigh.The
affectedplantpartsareremainsstunted,wilt,yellowishandkilledthehost
inseverecases
•Theflowersaresmallandappearsinred,white,yellow,pinkcolour
producedonaerialparts
ItbelongstothefamilyScorphulariaceae
Hosts–It attack mostly monocots such as maize, sorghum, pearl millet,
sugarcane, cowpea, sweet potato, tobacco and peanuts
Management
•Uprootinganddestructionofparasiticplantbeforeflowering
•Floodirrigationiseffectiveineliminatingtheparasite.
•Useofwitchweedinfectedfungiasbiologicalcontrol

9. Plant parasite Other names
Completestemparasite Cuscuta(Goldenvein,Dodder)
Partialstemparasite Loranthus/Dendrophthoe(Gaint
mistletoe,Banda)
Completerootparasite Orobanche(Broomrape,Tokra)
Partialrootparasite Striga(Witchweed)