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Introduction

Diseases and pests represent a majorthreat to the commercial production of

grapes in the world.

Climatic conditions are conducive to the

development of several major grapediseases, including black rot, downy and

powdery mildew.

Each of these diseases has the potential to

destroy the entire crop.

Most diseases occur simultaneously within

the same vineyard during the growing

season.

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Downy MildewCausal organism

Scientific Name: Plasmopara viticola

Symptoms

Leaves

oughly circular yellowishdiscolourations called !oil spots".

#hite fluffy growth primarily on the

lower leaf surface.

$s lesions age, they turn brown fromthe centre outward.

%everely infected leaves may drop.

Small, circularlesions on upper

side of leaf

Downey mildewgrowth on under

side of leaf

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Shoots

&nfected shoot tips curl and covered with whitefluffy sporulation.

Berries

#hite fluffy sporulation on small berries.

May shrivel and drop off.

%tay hard when healthy berries start to soften atveraison.

Downey mildew growth

on berries

Severely infected

berriesCourtesy'www. (hioline. osu. edu

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Biology )he causal fungus, Plasmopara viticola overwinters

as thick*walled oospores in infected tissues and inthe soil.

$ minimum of + mm of rain is re-uired for

oospores to produce sporangia that are dispersed byrain splash to young green tissue.

)he sporangia release motile oospores that swim to

the stomates, germinate and infect tissues.

Disease development is most rapid between /oCand /0oC with fre-uent rain or dew.

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Powdery mildewCausal organism

Scientific Name : Erysiphe necator (previouslyUncinula necator)

1osses in yield of fruits may be upto 2*34. &n addition to loss

of yield, infected berries tend to be higher in acid content than

healthy fruits and are unsuitable for wine making.

Symptoms:

(n all tissues, powdery mildew looks like a greyish*whitepowder.

Leaves

5re-uently first found on the undersides of leaves.

1esions become apparent on the upper sides of leaves as well.

(n rapidly growing leaves, infections on the underside may

cause the leaves to appear puckered on top.

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%everely infected leaves may become brittle and drop off.

%tarting as early as late 6uly, very small orange then brownand eventually black spherical structures cleistothecia

develop on the upper and lower surfaces of infected leaves.

Shoots

&nitially greyish*white, develop into brown irregular blotches.

&ndistinct margins and remain visible after shoot hardening.

Berries

7ecome covered in conidia.

$n initial floury appearance that later becomes dark and grey.

Dry out and may drop off.

1ater infections 89*2 weeks post bloom: will have superficial

greyish scarring.

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Severe powdery mildewon berries

Powdery mildew on upperside of leaves

Severe powdery mildewon cane

Powdery mildew on underside of leaves

Courtesy' www.oardc.ohio;grapeipm

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Black rotCausal organism

Scientific Name: Guignardia bidwellii

Symptoms

Leaves elatively small, brown circular lesions develop on infected

leaves and within a few days tiny black spherical fruitingbodies 8pycnidia: protrude from them.

Berries: &nfected berries first appear light or chocolate brown but

-uickly turn darker brown, with masses of black pycnidiadeveloping on the surface.

5inally, infected berries shrivel and turn into hard blackraisin*like bodies that are called mummies.

Shoots under high disease pressure brown to black elongated

lesions develop.

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Black rot lesions on

leaves

Mummied berriesInfected berry with

black pycnidia

Black rot berries

in cluster

iny blackpycnidia onleaf lesion

!longatedlesions on

petiole

Courtesy' .

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"nthracnose#Birds eye diseaseCausal organism

Scientific Name: Elsinoe ampelina

&t is especially serious on new sprouts during rainy season.

$mong various foliar diseases of grapevine in &ndia,

anthracnose has longest spell spread over the period from

6une to (ctober

Symptoms

Leaves

&nitially pin*prick dark spots.

Developing into small round spots with brown or black

margins with greyish*white centres which drop out causing

a @shot*holeA appearance.

%evere infections cause malformed leaves that shrivel up

and drop.

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Shoots

Deep elongated cankers

Greyish in the centre with a raised dark reddishbrown to violet-black edge

Infected shoots crack and become brittle

Berries Reddish circular spots becoming violet with agreyish centre and a raised black edge birds eyerot

esions can e!tend into the pulp" causing crackingand opening the berry to secondary infections

#everely infected berries dry up and dropprematurely$

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Sunken lesions onshoots

"nthracnose onberry

Birds eye rot symptoms on berryCourtesy'www.oardc.ohio;grapeipm

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5usarium #ilt

$ausal organismScientic %ame& Fusarium oxysporum#ymptoms%

#hoots and leaves wilt and die in mid-season" with characteristic brown-reddiscolouration of the vascular tissue ofthe a&ected areas$

eaves drop prematurely and clustersfail to develop and shrivel to mummies$#ymptoms range from one or two shootson a vine to whole plant collapse$

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Management

Collect and burn fallen leaves and twigs.

%anitation of the orchard is highly essential. Clean cultivation of vines or removal and destruction of all

diseased parts.

Bine should be kept high above ground to allow circulation of air

by proper %pacing row resistant varieties like Chholth ed, Chholth white, %kibba

ed 8

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ets sum up

Downey mildew pathogen causes irregular, yellowish,

translucent spots on the upper surface of the leaves and

white fluffy sporulation on small berries.(n all tissues, powdery mildew looks like a greyish*white

powderDue to black rot, infected berries shrivel and turn into hard

black raisin*like bodies that are called mummies.$nthracnose affected berries shows @shot*holeA

appearance.